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Waarom word koolstofdioksied in alkoholfermentasie geproduseer, maar nie in melksuurfermentasie nie?

Waarom word koolstofdioksied in alkoholfermentasie geproduseer, maar nie in melksuurfermentasie nie?



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Volgens my verstaan ​​vind alkoholfermentasie in gis plaas en laktaatproduksie vind by mense plaas.

Hierdie twee paaie vind slegs plaas as daar onvoldoende suurstof is, omdat die ander dele van metabolisme (TCA -siklus, ens) nie kan plaasvind soos dit in die mitochondria gebeur nie, wat O vereis2.

Vir alkoholfermentasie is daar koolstofdioksied, terwyl melksuurfermentasie nie koolstofdioksied produseer nie. CO2 word geproduseer wanneer daar 'n oksidasie van een koolstofmolekule is. My belangrikste vraag is dus: daar is 'n gebrek aan O2, hoe produseer gis CO2 terwyl mense dit nie doen nie?

Ook, hoe werk NAD+ herwin die hele tyd wanneer glikolise plaasvind?

Dankie !!!


Glikolise benodig 'n bestendige toevoer van NAD+ om te gebeur - dit is die drywer vir die anaërobiese oksidasie na laktaat en etanol, hoewel dit energeties baie minder gunstig is as die volledige oksidasie. Maar sonder suurstof is daar geen ander manier om die glikolise aktief te hou vir ten minste energie nie.

Die verskil is geleë in die ensieme wat beskikbaar is vir die omskakeling van die piruvaat. Dit is die Laktaatdehidrogenase in mense (en ander soogdiere) en die Pyruvaat dekarboksilase in gis. Die eerste kataliseer die reaksie van piruvaat na laktaat, die tweede van piruvaat na asetaldehied en CO2word die asetaldehied daarna omskep in etanol. Slegs die tweede stap produseer NAD+.

Sien die illustrasie (van hier af) vir verdere begrip:

Die mede2 geproduseer in hierdie reaksie vind nie plaas as gevolg van oksidasie nie, maar word vrygestel uit die dekarboksilering van die pyruvat. Sien die illustrasie hieronder (van hier af):

By die produksie van laktaat vind geen dekarboksilering plaas nie, wat die terugreaksie van laktaat na pyruvat moontlik maak sodra genoeg suurstof weer teenwoordig is.


Industriële biotegnologie en kommoditeitsprodukte

Abstrak

ABE-fermentasie, wat aan die begin van die 20ste eeu begin is, is gebruik om die asetoon of butanol te vervaardig vir die vervaardiging van kunsmatig sintetiese rubber, lak vir mobiele industrie sowel as die vervaardiging van kordiet tydens die Eerste en Tweede Wêreldoorlog. In die laaste helfte van die 20ste eeu het ABE -fermentasie egter afgeneem en sy ekonomiese mededingendheid verloor met die vinnige ontwikkeling van die petrochemiese industrie. Deesdae het die gretig na hernubare biobrandstowwe wetenskaplike en kommersiële belangstelling aangewakker oor die mikrobiese ABE -fermentasie vir die vervaardiging van biobutanol uit hernubare grondstowwe. Butanol as 'n gevorderde biobrandstof het groot aandag gekry vanweë sy omgewingsvoordele en voortreflike eienskappe teenoor etanol, soos hoër energie-inhoud, laer waterabsorpsie, beter vermengingsvermoë met petrol, en direkte gebruik in konvensionele verbrandingsenjins sonder verandering. Die koste van butanolproduksie via ABE -fermentasie deur Clostridiaal soos Clostridium acetobutylicum en Clostridium beijerinckii is nie ekonomies mededingend nie, wat die industriële toepassing daarvan belemmer het weens die swak butanol -toksisiteit en die relatiewe hoë koste van die substraat. As die genoomvolgorde van twee tipiese solventogeniese bakterieë C. acetobutylicum ATCC 824 en C. beijerinckii NCIMB 8052 vrygestel is, maak die sistematiese ontledings met behulp van omics-tegnologieë dit moontlik om nuwe insig in die klostridiale fisiologie en regulatoriese meganismes te verkry. Met die ontwikkelinge van genetiese manipulasie -instrumente en tegnieke vir die herwinning van produkte, beïnvloed die spanning en die stroomafwaartse proses die ekonomie van ABE -fermentasie groot. Hierdie artikel stel die basiese kennis oor die ABE-fermentasie bekend en som die huidige vordering op.


Bespreking en verduideliking

Die hipotese word ondersteun deurdat alle vorme van suiker energie produseer en dat glukose die doeltreffendste is.

Die koolstofdioksied wat geproduseer word, kan direk verband hou met die energie wat deur fermentasie geproduseer word, want koolstofdioksied is 'n neweproduk van etanolfermentasie (Cellular, 54). Die kontrole wat geen suiker bevat nie, lewer geen energie nie, omdat 'n bron van suiker nodig is vir die glikolise en fermentasie.

Glukose het die grootste tempo van energieproduksie gehad omdat die tempo van koolstofdioksiedproduksie die grootste was. Sukrose het die tweede hoogste produksietempo, terwyl fruktose die laagste van die drie suikers het. Glukose se tempo van energieproduksie was meer as drie keer dié van fruktose.

Glukose is direk in die glikolise-siklus gebruik en het geen ekstra energie benodig om dit in 'n bruikbare vorm om te skakel nie (Freeman, 154). Dit het ondersteun waarom glukose die doeltreffendste was.

Sukrose het 'n ensiem- en energie-insette benodig om dit in glukose en fruktose af te breek sodat dit in glikolise verwerk kon word (Freeman, 189). Fruktose kon ook nie onmiddellik in die glikolise ketting gebruik word nie, maar moes verander word om as een van die tussenprodukte in die ketting in te gaan (Berg, 2002).

Hierdie prosesse wat nodig is om die nie-glukose suikers om te sit in 'n bruikbare vorm, verminder hul doeltreffendheid in vergelyking met glukose. Die grootste bron van foute vir die eksperiment was die begintyd van fermentasie. Die gis is goed by die fruktose-oplossing gevoeg nadat die glukose- en fruktose-gisoplossings begin fermenteer het.

Fermentasie neem tyd om die maksimum tempo van energieproduksie te bereik, sodat die tydsgaping glukose en sukrose verder as fruktose in die fermentasieproses gelaat het (Berg, 2002). Die data oor die tempo van koolstofdioksiedproduksie was dus skeef omdat die begin van fermentasie nie beheer is nie.

Glukose en sukrose lyk baie doeltreffender as fruktose as gevolg van hierdie fout. As hierdie eksperiment herhaal word, sal ekstra sorg geneem word om te verseker dat fermentasie terselfdertyd begin. Die metings van suikers word in gelyke molariteit gemeet en nie in persent in 'n oplossing nie, sodat die suikermolekules gelyk is vir al die toetse.

Ander opvolgeksperimente kan die toets van ander giste insluit om te sien hoe die fermentasietempo beïnvloed word. Die resultate van hierdie eksperimente kan beïnvloed watter suikers die doeltreffendste is by alkoholfermentasie. Dit kan bepaal watter soorte suikerbrouers moet gebruik vir die doeltreffendste produksie van alkohol.

Help ons om sy glimlag reg te maak met jou ou opstelle, dit neem sekondes!

-Ons is op soek na vorige opstelle, laboratoriums en opdragte wat u uitgevoer het!

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Probleem: Giste ondergaan aërobiese selrespirasie as daar genoeg suurstof is en koolstofdioksied en hellip vrystel

Skrywer: William Anderson (Schoolworkhelper Editorial Team)

Onderwyser en vryskutskrywer. Wetenskaponderwyser en liefhebber van opstelle. Artikel laas hersien: 2020 | St. Rosemary-instelling © 2010-2021 | Creative Commons 4.0


Die wetenskap van suurkool: bakteriële fermentasie, Yum!

Verlede week het my man 'n paar flesse nodig gehad om te kook. Tesco verkoop potte vir ongeveer £ 3 elk. Hulle verkoop egter ook groot flesse vol suurkool vir £1 elk.

Verlede week het my man 'n paar flesse nodig gehad om te kook. Tesco verkoop potte vir ongeveer 3 stukke elk. Hulle verkoop egter ook groot flesse vol suurkool vir? 1 elk. Dit beteken dat ons die afgelope naweek baie suurkool gehad het om deur te kom.

Ek is nie 'n groot aanhanger van suurkool nie, wat jammer is, want die meeste van die smaak kom van die werking van bakterieë. Ook nie net een bakterie nie, maar 'n hele reeks verskillende spesies is by die fermentasieproses betrokke. Die bakterieë hoef nie eers by die suurkool gevoeg te word nie, aangesien hulle natuurlik op die koolblare leef. Al wat nodig is om die proses te begin, is gesnyde kool en sout.

Die eerste stadium van suurkoolfermentasie behels anaërobiese bakterieë, en daarom moet die gekerfde kool en sout in 'n lugdigte houer verpak word. In hierdie stadium is die omliggende omgewing nie suur nie, net kool. Die bakterieë, meestal Leuconostoc spesies, produseer koolstofdioksied (vervang die laaste oorblyfsels van suurstof in die fles) en melksuur, wat 'n natuurlike byproduk van anaërobiese respirasie is. Uiteindelik word die toestande in die pot te suur vir hierdie bakterieë om te oorleef en sterf hulle uit, vervang met bakterieë wat die suur toestand beter kan hanteers soos Lactobacillus spesies.

Die laktobacillus verder gis enige suikers wat in die kool oorbly, deur anaërobiese respirasie te gebruik. Dit produseer meer melksuur totdat die suurkool 'n pH van ongeveer 3. bereik. Hierdie bakterieë word belemmer deur hoë soutkonsentrasies (dus bevat die meeste suurkool ongeveer 2-3% sout) en lae temperature, en daarom moet die fermentasiepanne by kamertemperatuur eerder as in die yskas. By pH3 het die lactobacillus hou op om te fermenteer en die suurkool kan gestoor word totdat dit nodig is.

Al hierdie bakterieë help om die pittige suur smaak te skep, maar daar is maniere waarop mikrobiese groei verkeerd kan gaan. Groei van die laktobacillusAs die pot byvoorbeeld tydens 'n fermentasie by 'n te hoë temperatuur gestoor word, kan die suurkool die verkeerde konsekwentheid veroorsaak. Net so as die suurkool te vroeg te suur word laktobacillus kom vroeg in die aksie wat lei tot sagte suurkool. Alhoewel die voltooide suurkool heeltemal te suur is vir patogene om in te leef, kan swamspore op die oppervlak vestig en versprei, wat die kos bederf.

Alhoewel suurkool 'n Duitse woord is, het die gereg blykbaar sy oorsprong in China met kool gefermenteer in ryswyn of pekelwater. Dit het versprei na Europa deur middel van Ghengis Khan’s invallers waar die kool droog genees is met sout. Aangesien suurkool vir lang tye hou, en 'n bron van vitamien C is, is dit bevoordeel deur die Nederlandse matrose, wat dit saamgeneem het toe hulle na Amerika gereis het. Kaptein Cook het ook saam na Australië gereis, aangesien suurkool 'n reeks vitamiene en minerale bevat wat moeilik is om te bekom wanneer jy vir lang tye op see reis.

Aangesien die bakterieë wat nodig is vir suurkoolfermentasie op die koolblare voorkom, is dit 'n baie maklike en gesonde gereg om te produseer. Al wat jy nodig het is kool! Deur die werking van bakterieë te ontgin, kan eenvoudige bestanddele soos kool en soutwater gebruik word om 'n gesonde gereg te produseer wat geberg kan word lank verby die tyd wanneer rou vrugte en groente begin bederf het.

Die menings wat uitgespreek word, is die van die outeur (s) en is nie noodwendig die van Scientific American nie.

OOR DIE SKRYWER (E)

'n Biochemikus met 'n liefde vir mikrobiologie, die Lab Rat geniet dit om bakterieë te verken, te lees en daaroor te skryf. Nadat sy uiteindelik daarin geslaag het om haarself van die universiteit af te skeur, werk sy nou vir 'n klein maatskappy in Cambridge waar sy data in hanteerbare woorde en ongelooflike grafieke omskep.


Hierdie navorsing het ontstaan ​​as gevolg van 'n probleem in die biologieklas, wat na vore gebring is S. cerevisiae (Gis) met 'n substraat van koolhidrate soos maltose met die doel om hierdie disakkaried te fermenteer, wat die produksie van alkohol tot gevolg het. Op hierdie tydstip het die vraag na vore gekom dat as net van maltose gis die energie kan kry om te oorleef. Dit is om hierdie rede dat dit gedagte -ervaring was om mense in kontak te bring met die gis met ander koolhidrate.

Soos reeds in die inleiding genoem, produseer alkoholiese fermentasie CO2 en etanol. Met inagneming hiervan, in die eksperimentele ontwerp is om 'n totaal van vier substrate te gebruik: Glukose, maltose, sukrose en fruktose met die doel om aan te toon watter van hierdie substrate die gis 'n meer doeltreffende energietransformasie maak en meer koolstofdioksied produseer. Vir die bogenoemde is gebruik as 'n parameter, die vrystelling van CO2aangesien dit eweredig is aan die hoeveelheid substraat wat deur die gis gemetaboliseer word.

Onafhanklike veranderlike: Suikertipe.

Afhanklike veranderlike: Hoeveelheid CO2 binne 20 minute vervaardig.


Laboratorium verduidelik: Koolstofdioksiedproduksie deur giste onder verskillende temperature

Giste ondergaan aërobiese selrespirasie as daar genoeg suurstof is en koolstofdioksied as afvalproduk vrystel. Giste, soos enige ander selle, het 'n optimum temperatuur waarteen hulle die doeltreffendste werk, insluitend die proses van selrespirasie. Hierdie eksperiment het ten doel om die verband tussen temperatuur en die koolstofdioksiedopbrengs van giste te ontdek om die optimale temperatuur vir die uitvoering van aërobiese selrespirasie by giste te ontdek.

Daar word veronderstel dat giste aërobiese selrespirasie die doeltreffendste by hoë temperature uitvoer omdat hoë temperatuur waarskynlik die proses teen 'n hoër tempo sal aktiveer. Selle is die aktiefste by hoë temperature, maar binne hul hitteverdraagsaamheid, as die temperatuur 40 grade oorskry, sal giste, saam met hul ensieme, afsterf of gedenatureer word sodat hulle nie meer funksioneer nie. Inteendeel, lae temperatuur sal die giste nie laat werk nie, aangesien giste nie aangepas is vir 'n koue omgewing nie.

  • Onafhanklike veranderlike: temperature van 10% glukose -oplossing waarin giste geplaas word om aërobiese selrespirasie uit te voer (6 ° C, kamertemperatuur en 30 ° C is die temperature wat ondersoek word, hoewel die werklike kamertemperatuur in die laboratorium aangeteken word)
  • Afhanklike veranderlike: Verandering in CO2 konsentrasie nadat giste mettertyd by verskillende temperature in die glukose -oplossing geplaas is (CO2 -konsentrasie in 3 minute met 'n interval van 30 sekondes)
  • Konstante/gekontroleerde veranderlikes: konsentrasie van glukose-oplossing (10%), die massa glukose-oplossing wat by elke proef gebruik is (50 gm water en 5 gm glukose), die massa giste wat tydens elke proef gebruik is (250 mg), tempo van roer van die oplossing op die roerplaat (500 omw / min), tyd om CO2 -konsentrasie op te teken nadat giste ingesit is (30 sekondes, 1 minuut, 90 sekondes, 2 minute, 150 sekondes, 3 minute), chemikalieë gebruik (10% glukose -oplossing ), apparaat en toerusting (proefbuise, 100 ml bekers, 50 ml gegradueerde silinders met 'n onsekerheid van ±0,1 ml, 250 ml Erlenmeyer flesse, balans in g akkuraat tot 2 desimale plekke, 'n warm plaat wat ook 'n magnetiese roerplaat bevat en magnetiese roerstaaf, termometer wissel van 0°C tot 100°C met 'n onsekerheid van ±0.01°C, CO2 sensor wat aan 'n Xplorer GLX-masjien gekoppel word, proefbuisrakke, timer akkuraat tot 0,01 s, 1 spatel, 1 ysbad bestaan ​​uit 'n 50 ml beker en ysblokkies, 1 yskas)
  • Gis 1,5 g
  • Glukose 30 g
  • 500 ml gedistilleerde water
  • 4 100 ml bekers, onsekerheid ±5 ml
  • 1 termometer het gewissel van 0 ° C tot 100 ° C met 'n onsekerheid van ± 0,01 ° C
  • 12 proefbuise
  • 1 proefbuisrak wat 12 proefbuise kan hou
  • 1 gegoteerde silinder van 50 ml met 'n onsekerheid van ± 0,1 ml
  • 6 250 ml Erlenmeyer -flesse, onsekerheid is nie daaroor nie, aangesien dit nie gebruik word om volumes te meet nie
  • 1 Weegbalans in g akkuraat tot 2 desimale plekke
  • 1 spatel
  • 1 kookplaat wat ook 'n magnetiese roerderplaat bevat
  • 1 magnetiese roerstaaf
  • 1 CO2 -sensor word op die volle battery gelaai met 'n prop wat aan die kolf vasgemaak word
  • 1 GLX -masjien met 'n vol battery
  • 1 timer akkuraat tot 0,01 s
  • 1 ysbad, 1 50 ml beker ingesluit en 6 ysblokkies met 'n sylengte van ongeveer 1 sentimeter
  • 1 yskas met 'n yskaskompartement wat teen 'n temperatuur hoër as 0°C, ongeveer 0 tot 4°C verkoel

6 ° C glukose oplossing voorbereiding:

  1. 100 ml beker word gevul met gedistilleerde water
  2. 6 ysblokkies met sylengte van ongeveer 1 sentimeter word in die 100 ml beker met gedistilleerde water geplaas
  3. Die beker van 100 ml word eenkant in die yskas gelê met 'n temperatuur van 0 ° C tot 4 ° C, maar hoër as 0 ° C, sodat water nie oornag in die yskas vries nie
  4. Op die tweede dag word 5 g glukose geweeg op 'n weegbalans wat akkuraat is tot 2 desimale plekke
  5. 5 g glukose word in 'n proefbuis gesit en op die proefbuisrak geplaas
  6. Net so word 0,25 gram giste gemeet met 'n weegbalans wat akkuraat is tot 2 desimale en oorgedra na 'n proefbuis wat op die proefbuisrak geplaas word
  7. Die 100 ml beker wat in die yskas gebêre word, word uitgehaal en in 'n 50 ml -silinder gegooi met 'n onsekerheid van ± 0,1 ml om 50 ml yswater te meet, ysblokkies bly in die beker
  8. 50 ml yswater word in die 250 ml Erlenmeyer -fles gegooi
  9. Die Erlenmeyer -fles word op 'n kookplaat geplaas wat ook as 'n magnetiese roerplaat funksioneer en 'n magnetiese roerstang word in die fles gesit
  10. 5 gram glukose wat reeds in die proefbuis gemeet is, word in die water gegooi
  11. Die roerplaat word aangeskakel en teen 'n tempo van 500 rpm geroer
  12. Die roerplaat word afgeskakel sodra glukose heeltemal opgelos is
  13. 'n Termometer wat gewissel het van 0°C tot 100°C met 'n onsekerheid van ±0.01°C word in die glukose-oplossing geplaas, op hierdie stadium word die yswater opgewarm, die prosedure kan nie voortgaan totdat die temperatuur van die oplossing 6 bereik het nie. ° C
  14. Die CO2 -sensor is gekoppel aan die GLX -masjien wat die CO2 -konsentrasie in die lug vertoon
  15. Die CO2-sensor, wat aan 'n prop geheg is wat aan die nek van die fles bind om die vloei van lug te blokkeer, is in die fles ingebed
  16. Die CO2 -konsentrasie word op die GLX -masjien vertoon en word aangedui as die oorspronklike CO2 -konsentrasie in die fles
  17. Die CO2 sensor word uitgetrek en gis in die proefbuis word in die fles gegooi, CO2 sensor word terug in die fles gesit, die magnetiese roerplaat word aangeskakel teen 'n omwentelingstempo van 500 rpm, die stophorlosie is afgemerk, dit alles moet sonder tussenposes gedoen word
  18. Die mede2 konsentrasie in die fles word elke 30 sekondes vir 3 minute aangeteken so 6 getalle sal aangeteken word
  19. Die prosedure hierbo word nog twee keer herhaal

Voorbereiding van glukose-oplossing by kamertemperatuur:

  1. 100 ml beker word gevul met gedistilleerde water
  2. Die beker word oornag in die laboratorium geplaas
  3. Op die tweede dag word 5 g glukose geweeg op 'n weegbalans wat akkuraat is tot 2 desimale plekke
  4. 5 g glukose word in 'n proefbuis gesit en op die proefbuisrak geplaas
  5. 25 gram giste word geweeg op 'n balans wat akkuraat is tot 2 desimale plekke
  6. 25 g giste word na 'n proefbuis oorgeplaas en op die proefbuisrak geplaas
  7. Die gedistilleerde water in die 100 ml beker word in 'n 50 ml gegradueerde silinder met 'n onsekerheid van ±1 ml gegooi om 50 ml water by kamertemperatuur te meet
  8. 50 ml water word in die 250 ml Erlenmeyer -fles gegooi
  9. Die Erlenmeyer -fles word op 'n kookplaat geplaas wat ook as 'n magnetiese roerplaat funksioneer en 'n magnetiese roerstang word in die fles gesit
  10. 5 gram glukose wat reeds in die proefbuis gemeet is, word in die water gegooi
  11. Die roerplaat word aangeskakel en roer teen 'n snelheid van 500 rpm
  12. Die roerplaat word afgeskakel sodra glukose heeltemal opgelos is
  13. 'N Termometer wat wissel van 0 ° C tot 100 ° C met 'n onsekerheid van ± 0,01 ° C word in die glukose -oplossing ingevoeg, die gemete temperatuur moet die kamertemperatuur wees en word opgemerk vir verdere ondersoek
  14. Stappe 14 tot 19 in 6°C glukose oplossing voorbereiding van die laaste afdeling word herhaal

30 ° C glukose oplossing voorbereiding

  1. 50 ml gedistilleerde water word gemeet met 'n 50 ml -silinder met 'n onsekerheid van ± 0,1 ml
  2. 50 gedistilleerde water word na die 250 ml Erlenmeyer-fles oorgedra
  3. 5 g glukose word geweeg op 'n weegbalans wat akkuraat is tot 2 desimale plekke
  4. 5 g glukose word in 'n proefbuis geplaas en op die proefbuisrak geplaas
  5. 25 g giste word gemeet aan 'n weegbalans wat akkuraat is tot 2 desimale plekke
  6. Die gis word in 'n proefbuis gesit en op die proefbuisrak geplaas
  7. 5 gram glukose wat reeds in die proefbuis gemeet is, word in die fles in die water gegooi
  8. Die kolf word bo -op 'n warm plaat geplaas wat ook funksioneer by 'n magnetiese roerplaat, wat op 30 grade gestel is en die roer teen 'n snelheid van 500 rpm aangeskakel word.
  9. Die roerplaat word afgeskakel sodra glukose volledig opgelos is
  10. 'n Termometer wat gewissel het van 0°C tot 100°C met 'n onsekerheid van ±0.01°C word in die glukose-oplossing geplaas om die verandering in temperatuur te monitor
  11. Sodra die temperatuur 30 ° C bereik het, word die termometer uitgehaal en die plaat afgeskakel
  12. Stappe 14 tot 19 in 6 ° C glukose oplossing voorbereiding uit die tweede laaste afdeling word herhaal

Metodes van beheer van veranderlikes:

Die onafhanklike veranderlikes is temperature van 10% glukose -oplossing waarin giste geplaas word om aërobiese selrespirasie uit te voer. Hulle is onderskeidelik 6°C, kamertemperatuur en 30°C.

Die metodes om die onafhanklike veranderlikes te manipuleer word in die prosedure verduidelik. Kortliks, 6°C glukose-oplossing moet 'n gedistilleerde water in 'n ysbad gestoor word en in die yskas-kompartement van 'n yskas geplaas word. Let daarop dat dit nie in die vrieskas geplaas kan word nie, anders sal die gedistilleerde water gevries word en kan dus nie gebruik word nie. Oornag sal die temperatuur naby aan die temperatuur van die yskaskompartement wees, wat tussen 0 en 4°C moet wees.

Die water word die tweede dag uitgehaal en die temperatuur word gemeet met 'n termometer wat wissel van 0 ° C tot 100 ° C met 'n onsekerheid van ± 0,01 ° C. Die temperatuur sal waarskynlik tydens die proses styg, so sodra die temperatuur 6°C bereik, kan die res van die prosedure uitgevoer word. Die glukose -oplossing by kamertemperatuur benodig 'n soortgelyke opstelling as die 6 ° C -oplossing. Gedistilleerde water vul die 100ml-beker en word oornag in die laboratorium geplaas om water by kamertemperatuur te benodig.

Die kwantitatiewe analise moet egter opgemerk word. Die 30°C glukose-oplossing benodig 'n warm plaat. Gedistilleerde water word op die kookplaat op 30 ° C verhit en 'n termometer met gedistilleerde water in die fles geplaas om temperatuurverandering te monitor. Sodra die temperatuur 30°C bereik, word die warmplaat afgeskakel en die res van die prosedure moet onmiddellik uitgevoer word sodat die water of die glukose-oplossing nie afkoel nie.

Die afhanklike veranderlike is die verandering in CO2 konsentrasie nadat giste met verloop van tyd by verskillende temperature in die glukose-oplossing geplaas is. 'N Mens sou die aanvanklike CO opneem2 konsentrasie van die glukose -oplossing voordat giste ingesit word om die voorraadkonsentrasie van CO te verkry2 in die fles. Toe het die CO2 konsentrasie in die fles word aangeteken met 'n 30 sekondes interval nadat gis vir 3 minute ingesit is, dus na 30 sekondes, 1 minuut, 90 sekondes, 2 minute, 150 sekondes en 3 minute die CO2 konsentrasie word aangeteken. 'n Mens sal 'n timer hiervoor nodig hê.

Die eksperimenteerder kan die data aanteken en dit in 'n grafiek van CO teken2 konsentrasie in die fles met verloop van tyd. Met die grafiek sal 'n mens die aanvanklike CO aftrek2 konsentrasie van die CO­2 konsentrasie, die CO2 konsentrasie op 30 sekondes vanaf die CO2 konsentrasie op 1 minuut, ensovoorts, om die verskil van CO te verkry2 konsentrasie tussen elke interval om die algehele veranderingstempo in CO te monitor2 konsentrasie by verskillende temperature waarin giste aërobiese selrespirasie uitvoer.

Een beheerde veranderlike is die konsentrasie van glukose-oplossing, wat op 10% gehou word deur 5 gram glukose te meet met 'n weegbalans akkuraat tot 2 desimale plekke en dan word die glukose in 'n 50 ml gedistilleerde water gegooi, gemeet deur 'n 50 ml gegradueerde silinder met 'n onsekerheid van ± 0,1 ml, gemeng deur die magnetiese roerplaat en staaf. Hierdie proses word uitgevoer in al drie temperature.

'N Ander konstante is die massa glukose -oplossing wat by elke proef gebruik word. Soortgelyk aan die vorige, word 50 g gedistilleerde water gemeet met 'n 50 ml -silinder en 5 g glukose met 'n weegbalans. Hulle sal gemeng word met 'n magnetiese roerplaat en 'n magnetiese roerstaaf wat in die Erlenmeyer-fles geplaas word wat die gedistilleerde water en glukose bevat.

Let daarop dat die glukose in 'n proefbuis gestoor kan word en opsy gesit word, en wanneer dit in die fles met gedistilleerde water gegooi word, word die proefbuis liggies gestamp om te verseker dat glukose nie aan die binnekant van die proefbuis kleef nie. 5 g glukose gaan in die fles.

Die massa giste wat by elke proef gebruik word - 250 mg - is nog 'n beheerde veranderlike. Soos glukose, word giste ook gemeet met 'n weegbalans akkuraat tot 2 desimale plekke in gram. Om gis te weeg en dit in 'n proefbuis oor te plaas kan moeilik wees, ekstra konsentrasie is nodig.

Die roersnelheid van die oplossing op die roerplaat is 500 omwentelinge per minuut. Die aanwyser moet oorgeskakel word na 500 rpm met die magnetiese staaf in die oplossing geplaas en met giste, as getalle rpm nie getoon word nie, word die omwentelingstempo eerder na medium oorgeskakel.

Nog 'n konstante is die tyd om CO aan te teken konsentrasie nadat gis ingesit is. Die tyd is 30 sekondes, 1 minuut, 90 sekondes, 2 minute, 150 sekondes, 3 minute. 'n Stophorlosie of 'n timer word vereis en ook akkuraat tot 0.01 s. Met hierdie tussenposes van 30 sekondes het die CO2 konsentrasie word vertoon op die GLX-masjien wat aan die CO gekoppel is2 sensor, word die nommer afgedraf deur te kyk na die nommer wat in ppm vertoon word.

Die chemikalieë wat gebruik word, dit wil sê 10% glukose -oplossing, is 'n ander beheerde veranderlike.

Onthou net glukose, nie ander suikers nie, word in hierdie eksperiment ondersoek. Die apparaat en toerusting wat gebruik word, is ook konstantes. Dit is 12 proefbuise, bekers van 100 ml, silinders van 50 ml met 'n onsekerheid van ± 0,1 ml, 250 ml Erlenmeyer -flesse, balans in g akkuraat tot 2 desimale plekke, 'n kookplaat wat ook 'n magnetiese roerderplaat en magnetiese roerstang bevat , termometer wissel van 0°C tot 100°C met 'n onsekerheid van ±0.01°C, CO2 sensor wat gekoppel is aan 'n Xplorer GLX -masjien, proefbuisrakke, timer akkuraat tot 0,01 s, 1 spatel, 1 ysbad bestaan ​​uit 'n beker van 50 ml en ysblokkies, 1 yskas.


Koolsuur in suur biere

Ek het onlangs een van my gunsteling jaarlikse suurbier -geleenthede, Cantillon Zwanze -dag, bygewoon. Zwanze -dag, wat elke herfs gehou word, is 'n dag om tradisionele Belgiese lambics en die produkte van die Cantillon -brouery te vier. Elke jaar stel Cantillon 'n ander unieke bier vry vir die geleentheid wat terselfdertyd op alle plekke wêreldwyd getik word. Soos ons die afgelope paar jaar het, het ek en my lewensmaat na die naaste plek gereis waar die geleentheid aangebied is, Monk’s Cafe in Philadelphia, en 'n wonderlike dag gehad om hul Belgiese styl kombuis en 'n fantastiese verskeidenheid draft Cantillon en ander groot suur te geniet. biere. Een van die biere wat ek op tap gedrink het, was Cantillon Rosé de Gambrinus, wat ek deur die jare die geleentheid gehad het om in beide konsep- en gebottelde weergawes te geniet. In konsep en bottel het ek opgemerk dat verskillende koolzuurvlakke die manier waarop ek hierdie bier waarneem en geniet, aansienlik kan verander. Hierdie gedagtes het my aangespoor om die koolzuurvlakke in suur bier te bespreek, beide uit 'n brouers- en 'n verbruikersoogpunt.

Die basiese beginsels & # 8211 Wat is Carbonation?

Koolstofdioksied, 'n eenvoudige molekule wat uit een koolstofatoom en twee suurstofatome bestaan, is 'n natuurlike byproduk van 'n groot aantal chemiese reaksies wat meer komplekse koolstofverbindings afbreek. In die geval van suurbierproduksie, is hierdie koolstofverbindings die eenvoudige suikers wat in wort voorkom, en die chemiese reaksies is die alkoholproduserende fermentasies van gisspesies, soos Saccharomyces en Brettanomyces asook sekere (heterofermentatiewe) stamme van die bakterieë Lactobacillus.

Vir die ernstige chemie geeks..

Vir so 'n relatief eenvoudige molekule kan die chemie van koolstofdioksied baie kompleks wees. Vir ons bespreking gaan ons egter net fokus op een belangrike deel van hierdie chemie: As koolstofdioksied in water oplos, kan een molekule koolstofdioksied met een molekule water saamkom om koolsuur te produseer. Die vorming van koolsuur is die rede waarom koolstofdioksied meer vir 'n bier doen as om dit net bruisend te maak. Koolsuur verlaag die pH van 'n bier en dra die geureffekte mee wat ander sure in bier ook dra. Hou in gedagte dat koolzuur nie die pH van 'n bier drasties genoeg sal verander om dit suur te maak nie. Koolsuur kan egter 'n bier se bestaande suurheid in die mond beklemtoon.

Wat die smaak -effek daarvan op bier betref, word alle koolstofdioksied ewe veel geskep. Dit is waar, ongeag of die karbonasie natuurlik deur fermentasie geskep word of by 'n bier in drukvate gevoeg word. Dit gesê, die proses van bottel- of vaatjie-kondisionering kan subtiele dog noemenswaardige veranderinge in geur veroorsaak as gevolg van effekte wat deur beide ervaar word. Saccharomyces en Brettanomyces wanneer dit onder druk fermenteer. Hou in gedagte dat hierdie effekte subtiel en spanningafhanklik is. As ons gewoonlik 'n verskil in karakter tussen 'n suur of 'n plaashuis sien wat in 'n bottel gekondisioneer is teenoor kragkoolzuur, is die verskil bloot te wyte aan 'n hoër koolzuurvlak in die bottelversorgde weergawe.

Koolsuurvlakke en hul gevolge

Vir elke klassieke bierstyl is daar 'n algemene reeks koolzuurvlakke wat as geskik vir die styl beskou word. Hierdie vlakke, gemeet in volumes CO2, organies ontwikkel vir elke styl, gebaseer op die beste smaak vir die bier sowel as op die fermentasie- en bedieningsmetodes wat histories ontwikkel is. Byvoorbeeld, baie Britse biere word tradisioneel uit houtvate bedien ('n laedrukvat), en dit is gewoonlik die minste koolzuurhoudende style, wat wissel van 0,75 tot 1,5 volumes CO2. Aan die ander kant van die spektrum, en van meer belang vir suurbier-aanhangers, het Belgiese Gueuze nie as 'n styl bestaan ​​totdat glasbottels in staat was om sjampanje-vlakke van CO te hou nie.2 beskeie beskikbaar geword het. Gueuze is per definisie 'n bottel -gekondisioneerde styl en word daarom gereeld bedien by hoër druk wat hierdie nuwe houers kon bevat, 3.0 tot 4.5 volumes CO2.

Dit laat die vraag ontstaan: Historiese konvensies tersyde gestel, sal 'n British Mild goed smaak teen hoë karbonasie en 'n Gueuze smaak goed by lae carbonation? Die antwoord: Wel, dit hang af. Ten spyte van die feit dat baie van ons 'n goeie smaak en 'n persoonlike smaak is, is daar bier se eienskappe wat min of meer indrukwekkend kan wees deur hoër of laer koolzuurvlakke. Laer koolzuurvlakke beklemtoon die soet moutgeure in 'n bier. Hulle is ook geneig om 'n gladder, potensieel romeriger, afwerking te produseer. Hoër koolzuurvlakke verminder die soetheid van mout, terwyl dit die waarneming van bitterheid en/of suurheid in 'n bier verhoog. Hulle dryf ook meer aromatiese verbindings uit die bier (versterkende aroma) en laat die afwerking droër en skerper voel. In die geval van 'n British Mild, 'n lae alkoholbier met ryk moutgeure en 'n subtiele gebraaide karakter, kan te veel koolzuur die bier dun laat voel op die verhemelte, met minder soetheid en 'n meer saamtrekkende geroosterde kwaliteit. Aan die ander kant kan 'n koolzuurhoudende Gueuze soeter smaak as wat bedoel is, terwyl dit in die aroma-afdeling as 'n gebrek aan smaak lyk.

Additionally for Gueuze and other traditional lambics, I feel that lower levels of carbonation can accentuate the perception of their acetic acid and ethyl acetate components. These chemicals are present to at least some degree in all traditional lambics, but can be perceived as off-flavors if their levels are too high or if other elements of the beer are left unable to balance them. When properly balanced by lactic, malic, and carbonic acids, acetic acid will give a sour beer a round, complex, salivation producing acidity. If unbalanced, acetic acid can taste like vinegar, be harsh, or even burning in the throat. Ethyl acetate at low levels will smell like pears and provide a sharpening edge to a beer, while at higher levels this chemical will smell solventy, like nail polish remover. Traditional lambic brewers and blenders have the skill to optimize the levels of both of these components in their Gueuze and fruit lambics. Therefore, the level of carbonation and equivalently carbonic acid in the finished product can tip the scales in one direction or the other when it comes to perceiving these chemicals.

Carbonation from a Brewer’s Perspective

As a brewer, I want to provide my drinking audience with a beer that has at least enough carbonation to showcase its flavors and aromas in the best possible way. For my palate, this means erring slightly on the high side of the carbonation spectrum for the individual styles of sour beer that I produce.

When sampling base beers or testing out a blend, I am a big fan of using a simple set of tools that allow a brewer to quickly cool and carbonate a sample before tasting. This setup uses a plastic cap which screws onto most standard water or soda / pop bottles and connects to a ball lock gas fitting. With this low cost tool, we can taste small samples of a beer as they will taste when finished with carbonation. As mentioned earlier, carbonation can dramatically alter our perception of flavor and aroma when tasting a beer. Therefore I find it incredibly useful to be able to taste small carbonated samples without having to commit an entire batch to keg or bottle.

As a homebrewer who serves most of my beer on draft, hitting a desired carbonation level is a fairly straightforward process. When a blend is ready, I will transfer the beer to a keg and force carbonate it to the desired level. If bottling, I use counter pressure filling to ensure that every bottle I produce will have about the same carbonation level as the beer that I am tasting on draft. As a homebrewer, these processes are simple and effective, but have a few limitations. First, they are more expensive than bottle conditioning, requiring more equipment. Second, they may be difficult to scale up for professional breweries, as pressurized bottling or canning lines are very expensive and present unique sanitation challenges when working with Brettanomyces and bacteria. Third, the higher the desired carbonation level, the more challenging it is to dial-in handheld or automated counter-pressure bottle fillers. At CO2 volumes above 3.0, excessive foaming and associated low bottle fills and/or excessive wasting of product can easily occur.

At face value, bottle conditioning is a simpler overall process than force carbonation and allows a brewer to target higher levels of carbonation than are practical with other methods. Additionally, bottle conditioning requires less investment in equipment. Unfortunately, bottle conditioning can be less predictable and comes with its own unique set of challenges when dealing with mixed microbe fermentations. The bottle conditioning process for “clean” Saccharomyces-only beers is relatively straightforward and is calculated from a few basic pieces of information including:

  • Die hoeveelheid CO2 dissolved in a beer after fermentation.
  • The potential residual fermentability of the beer.
  • The desired volumes of CO2.

The inherent difficulty and potential unpredictability of bottle conditioning sour beers arises from three potential issues that need to be dealt with:

  • Long aging times can make our estimates of dissolved CO2 onakkurate.
  • Unless a recipe has been brewed and aged several times using the same strains of microbes, it’s residual fermentability could be nearly impossible to guess. Many strains of Brettanomyces can be hyperattenuative, continuing to slowly ferment the complex residual carbohydrates for months or even years after the primary fermentation is complete.
  • Aggressive strains of Lactobacillus of Pediococcus can convert some portion of simple priming sugar into lactic acid, a process which will not produce any additional carbon dioxide.

A certain amount of unpredictability will always exist when bottle conditioning sour beers. Luckily, these styles do taste great within a wide range of potential carbonation levels and there are some best practices that can help us hit those numbers:

  • When calculating the amount of residual CO2 in your beer, use the highest temperature that the beer reached during its aging period. If a beer was barrel aged, Michael Tonsmeire recommends halving the CO2 estimate. Check out his Priming Sugar Spreadsheet on The Mad Fermentationist Blog.
  • When bottling a beer with Brettanomyces, closely track the beer’s attenuation during its aging. I would recommend against bottling any beer with a specific gravity of 1.008 or less that has not had a stable attenuation for at least 3 months. If a beer has a specific gravity higher than 1.008, I would recommend observing a stable gravity for 6 months before bottling. The only time I would consider bottling younger is if you have brewed the exact beer previously and have a clear expectation of what the final gravity will be. Remember that this practice also applies to counter-pressure filled bottles. Unexpected rises in attenuation can lead to over-carbonation in these beers as well.
  • When bottling a mixed microbe beer, do not introduce new yeast or bacteria strains at the time of bottling. If adding fresh Saccharomyces of Brettanomyces, make sure to use strains that already exist within the beer. Select bottles that can tolerate higher than expected carbonation pressures. No brewer wants to release beers that gush when opened, but it is a far better accident than bottles that explode. If your beer does continue to attenuate after bottling, it will gain approximately 0.5 volumes of CO2 for every point of specific gravity lost. For example: If a beer is bottled at 1.008 SG, and it drops to1.000 SG, it will gain 4 unintended volumes of CO2 in addition to whatever carbonation was provided by priming sugar. Such unexpected attenuation would put the total carbonation of the beer to between 6-7 volumes. Champagne bottles are the only glass containers on the market that can handle these pressures without exploding.

Luckily, it’s rare for any beer which has had a stable gravity over several months to later ferment to 100% apparent attenuation after bottling. While it may be rare, it is however possible, and this has led many professional sour brewers to avoid bottling any beer with a final gravity higher than 1.008 (2 Plato).

For references on performing the actual calculations needed to bottle condition your beers, check out these resources:

Like any brewing process, repetition and experience with your recipes, strains, and fermentations will help take the guesswork out of proper carbonation. I personally err on the side of slighter higher carbonation levels because, as we will see, from a consumer’s standpoint, it’s relatively simple to remove a little extra carbonation from a beer but it is practically impossible for the drinker to add more CO2 to a flat beer.

Carbonation from a Consumer’s Perspective

As sour beer drinkers, we will encounter beers that range from completely still (intentionally or unintentionally uncarbonated) to those with such high carbonation levels that the beers may gush a little (or a lot) upon opening.

When I am trying a new sour beer for the first time, I always open the beer with the assumption that it may be slightly over-carbonated. Regardless of how a beer has been cellared, I prefer to put my sour beers upright into a refrigerator for at least a few days (but more frequently for several weeks) before opening them to allow for yeast and other sediment to settle to the bottom of the bottle and for any carbonation that may have been agitated out of solution by transport to stabilize. When I open a bottle, I like to do so with enough glasses to serve the beer ready to go. If a beer does begin to foam up once opened, having several glasses available can keep from losing beer to spillage that may have been perfectly delicious to drink. Unlike “clean” styles, which generally become very unappealing if they become over carbonated via hyperattenuative wild yeast strains, sour beers tend not to suffer a dramatic drop in flavor quality if they become over-carbonated.

This bottle of Oud Beersel’s Oude Kriek Vieille is an example of a beer that I may consider degassing.

Some sour beers may be purposefully carbonated to the higher end of the range for their styles. It is quite common to find Gueuzes, Fruit Lambics, and Farmhouse Ales with carbonation levels ranging from 3.5 to 4.5 volumes of CO2. While these beers may not gush upon opening, their very high levels of carbonation, in my opinion, can make it difficult to taste the wide variety of other more subtle characteristics in the beer. Beers such as this may benefit from the drinker actually allowing some of the carbonation to escape the beer before consumption. My rule of thumb in regards to this goes as follows:

  • If I pour a beer into my glass that seems to be very highly carbonated (creates a large volume of head with a moderately gentle pour and continues to bubble strongly), I will slowly take a sip of it into my mouth and hold it there.
  • Once in my mouth I will feel how the beer is reacting on my tongue. If the beer feels so spritzy / prickly in my mouth that I’m not actually able to taste much beyond the sensation of carbonation, then I may consider removing some of the extra CO2 from the beer. The best way that I can describe this sensation is to say that if feels like more gas bubbles are hitting your taste buds than actual liquid.
  • The easiest way to remove some extra CO2 from a beer is to pour it gently once or twice from one glass to another, this will release additional carbonation in the form of head with each pour.
  • A second way to degas a highly carbonated beer is to pour it into a decanter and allow it to rest and open up over a period of 10 to 20 minutes. This is very similar to a process used to open up certain varieties of wine and can be done using the same containers. Lambics from the brewery Drie Fonteinen are a classic example of beers that often benefit from some degassing. Their master blender Armand Debelder highly recommends it and I can attest that doing so does bring out a wide range of complex flavors in his blends that may be otherwise missed.

Drie Fonteinen’s Golden Doesjel is an example of a lambic beer served intentionally still.

On the other end of the spectrum exist a wide number of sour beers which are purposely bottled still or with very low carbonation. This is the norm for unblended Lambic and is also often the case for certain single barrel American sour releases. In my opinion, the best way to serve these beers is at the high end of cellar temperature, 55 to 60 F. To help drive aromatics, I will give these beers a vigorous pour and often drink them a little more slowly, allowing some oxygen to gradually mix into the beer. It is interesting to see how these still varietals will open up and change in character over the course of 30 to 60 minutes.

Ending Thoughts

From a brewer’s perspective, sour beers generally undergo complex fermentations with a variety of microorganisms. In some cases the exact organisms involved may be unknown. While we can make educated guesses which tend to become more accurate with experience brewing and fermenting a particular recipe, miscalculations do occur. In fact, they occur rather frequently. This fact leads to a wide variability between the carbonation levels of different sour beers, and even between different batches of the same sour beer. To compound the matter, safety and the prevention of exploding bottles is a very real concern on the minds of sour brewers who distribute their products. That being said, carbonation doesn’t have to be a total shot in the dark. The keys to success in hitting a desired carbonation level are patience, accuracy in measurements, and detailed note taking for future repeatability.

From a consumer’s perspective, we are sometimes disappointed by sour beers that may have a lower or higher amount of carbonation than expected. Fortunately, most sour beers have redeeming flavors at a wide range of carbonation levels. Additionally, there are methods that we as drinkers can use to maximize our enjoyment of these beers.

Hopefully this article has provided both an understanding of the complexities of carbon dioxide in relation to sour beers as well as some practical tips for both the brewers and consumers who love these styles. As always, I welcome your thoughts and questions on the topic!

Cheers!
Matt “Dr. Lambic” Miller

Okay.. Technically its not “impossible” for the consumer to add their own carbonation.. but you’ve got to be a nutcase like your’s truly to bother doing so! Cheers Sour Fans!

Goodwin, Jay, and Scott Moskowitz. “The Sour Hour / Episode 4.” The Sour Hour. The Brewing Network. Concord, CA, 20 Nov. 2014. Radio. (Troy Casey of Casey Brewing & Blending discusses bottle conditioning)

Palmer, John J. How to Brew: Everything You Need to Know to Brew Beer Right the First Time. Boulder, CO: Brewers Publications, 2006. Print.

Steen, Jef Van Den. Geuze & Kriek: The Secret of Lambic. Tielt, Belgium: Lannoo, 2011. Print.

Tonsmeire, Michael. American Sour Beers: Innovative Techniques for Mixed Fermentations. Boulder, CO: Brewers Publications, 2014. Print.


What Are the Waste Products of Respiration?

In animals, such as humans, the waste products of aerobic respiration are water and carbon dioxide, and the waste product of anaerobic respiration is lactic acid. Aerobic respiration is a series of reactions that sees oxygen being consumed in order to release energy from glucose. Anaerobic respiration occurs when there is an oxygen debt in cells.

Aerobic respiration happens mostly within the mitochondria in eukaryotic cells and the energy found in these cells is in the form of adenosine triphosphate (ATP). Respiration is essentially a production process for ATP. During the process, glucose goes through glycolysis, which creates pyruvate and ATP. If there is oxygen available, this pyruvate is oxygenated, creating acetyl-CoA, and moved on to the mitochondrion where more ATP is produced and both water and carbon dioxide are given. Both the water and the carbon dioxide combine to make carbolic acid, which helps maintain the blood's pH levels.

If there is no oxygen available to the pyruvate after glycolysis, the pyruvate enters a process of fermentation. This is known as anaerobic respiration, and it is used when muscle cells have exhausted their oxygen supply. During aerobic respiration, up to 38 ATP can be produced however, in anaerobic respiration, only two are produced. When oxygen is available again, NAD+ in the cell forms with the hydrogen in lactic acid to form more ATP.


Why is carbon dioxide produced in alcohol fermentation but not in lactic acid fermentation? - Biologie

Have you ever wondered about how small germs are?
And what are germs anyway?
Are you always being told to wash your hands? Weet jy hoekom?

The tiny things you know of as germs are known as bacteria by scientists. They are very small and you can't see them. Many thousands could fit on a pin head. They are alive, in the same way that you are, or a dog is, or a
plant is. The study of these and other small living things or organismes is genoem Mikrobiologie.

What is a microbiology?

Mikro means very small and biologie is the study of living things, so microbiology is the study of very small living things normally too small tobe seen with the naked eye.

Aktiwiteit Using Microscopes

What sort of small, living things do microbiologists study?

First we need to understand the classification of all living organisms. We also need to understand the fundamental characteristics of different types of organisms. As outlined in the classification, microbiology includes the study of:

bacteria (or Eubakterieë ) fungi (or Archaeobacteria )
protists archaea algae However, there are other organisms that are studied by microbiologists and these cannot be classified as living by the conventional definitions.

No. It is true that some microbes cause disease and others cause decay and damage to inanimate objects, but without microbes we would not be able to exist. Microbes are everywhere and the more we look the more we find, sometimes in the most unlikely of places.

Our body is infested with microorganisms and most of them are essential for our survival. They assist in food digestion in our digestive system, for instance.

Even microbes that cause decay are useful for they breakdown dead matter into simple chemicals, so the matter can be recycled and used by other - probably more complex - life forms. Without the decay process, the world would soon be covered in dead creatures and plants.

Microbes have different functions for different purposes and to occupy different niches in the biology of the planet. They have evolved when and where they had the opportunity, without any moral imperative. But as humans, we find that some are useful to us and others are dangerous to us. So we view them as either good or bad.

"Goed" microorganisms include those that are necessary to maintain our environment, in a way that will support our existence. Then there are our very own microorganisms that our body uses as part of its internal defense system, to fight infection from outside.

"Sleg" microorganisms enter the body in a number of different ways, but most commonly by the respiratory and digestive system, or by damaged skin. They cause problems to the body because they destroy body tissue and release toxic substances. This upsets the normal running of the body, which has to divert energy to its internal defense system in order to fight the invader.

Microorganisms that cause disease include:

Firstly, it should be understood that all living things "work" in the same way at the most basic level. There are certain structures and functions that are common to all living organisms. Likewise all living things use similar chemical processes to work - this is known as organic chemistry. One chemical element above all others dominates organic chemistry - carbon. This has some unique properties that allow trillions of different chemicals to be made from a few chemical elements. An account of why carbon is the basis of life is shown here.

Lets us look at some of the key structural and chemical components of living organisms in general and microbes in particular.

Die sel
All living organisms are made from selle . They are the basic unit from which living things are constructed and the smallest part of an animal or plant that can function independently. All cells have an outer coat or membrane that is resilient to the external environment. It is tough and resists damage to the cell, physically, chemically and biologically. It also provides a good internal environment with a boundary where life processes can be performed by the organic chemicals inside the cell. The boundary is important, too, because that stops the contents of the cell from being dispersed.

Prokaryote cells lack a nucleus, and consist of a cell membrane in which several distinct components function. Typically these are:

Chromosomes - A coiled strand of DNA
Ribosome - Factory-like elements of a cell, where messenger RNA is turned into proteins - building blocks and enzymes - the cell needs
Sitoplasma - The general cell contents
Glycogen granules - to provide energy

Prokaryotes often also possess flagella, which help them move.

Eukaryote cells have additional internal components, notably a nucleus and mitochondria.


Chloroplast Mitochondria
© 1999 The Centre for Microscopy and Microanalysis

Enzymes are organic catalysts which speed-up an organism's chemical reactions, without changing themselves. Chemical reactions can often be speeded up by heating, but in the case of living organisms this can damage them. The enzyme, which is usually protein with a specific shape for each purpose, controls the chemical reactions in the cell and thus allows the organism to metabolize.

There are two groups of enzymes: intracellular and extracellular. The former exist inside cells, controlling the metabolic rate. The latter are produced by cells, but work outside of these. For instance, digestive enzymes are used by the body to break down food in the digestive system.

Enzymes speed up reactions, without being destroyed by the reaction itself. They will not work in high temperatures, or at the wrong pH balance. Each enzyme has a specific function, but it can work in either direction of the chemical reaction.

DNA , deoksiribonukleïensuur, is a complex molecule containing instructions for all the functions of the cells of an organism, its "genetic information". It replicates itself by separating its two interwoven strands (the helix) like a zip fastener and attracting free nucleotides (simpler molecules of nucleic acid) in the same order as the original.

The DNA molecule is a double helix made of four types of nucleotide. These are aligned in a ladder formation, which is twisted like a screw. On opposite sides of the double helix are companion nucleotides. Adenine (A) en Thymine (T) are always located opposite other, and so are Guanine (G) en Cytosine (C) . So, each strand of the double helix is a "mirror image" of the other. This is why A, T, G and C are the four letters associated with the genetic code.

DNA is the "master copy" for all the instructions for the cells of the organism.

The image shows the double helix structure of the DNA, which consists of two strands with the cross links at intervals joined be hydrogen bonds. There are ten crosslinks for every complete twist of the double strand. The lower image shows a section of the DNA helix, untwisted. It shows the main components of the strand: Sugars (pentagonal shapes), phosphates (spheres) and organic bases (A, C, G and T).

To replicate, the DNA unzips along the center of the rungs of the ladder. The exposed free ends can then form two new DNA strands by allowing "partner" molecules to link at the exposed rungs. A can only pair with T, and C with G.

RNA , ribonukleïensuur, is a much smaller molecule than DNA, which copies the information and takes part in the process of protein synthesis in cells. It differs from DNA in that Urasil (U) vervang Thymine. Unlike DNA it can interact with other molecules, specifically ribosomes. The RNA copy of the DNA information is transcribed from the DNA template, this is known as transcription RNA, this is the copied message of the DNA.

mRNA , messenger RNA, is a further copy of the RNA transcript which has been spliced and modified. It carries the information from the DNA which specifies an amino acid sequence of proteins. In a eukaryote it then moves out of the nucleus into the cytoplasm, where it attaches to the ribosome. In a prokaryote, which does not have a nucleus wall, the next process takes place on-site. mRNA is the new message of instructions from the DNA.

tRNA , oordrag RNA, is the adapter molecule which allows the mRNA nucleotide sequences to be translated into protein amino acid sequences. The tRNA anticodons link up to their corresponding codons of the mRNA, one at a time, as the mRNA moves through the ribosome. Dit is vertaling . tRNA is the receiver of the message.

rRNA , ribosomal RNA, occurs with proteins to make up the ribosome which provides the site for translation to occur. Ribosomes can be be located in clusters, or as free individuals, depending upon the final purpose of the altered proteins. Ribosomes are the "factories" that use the message to make essential chemicals for a cell to function.

Chromosomes and Genes are very long thread-like structures in the nucleus of eukaryotic cells, that carry the hereditary information of the cell. They contain a long length of double-stranded DNA coiled up - the famous Double Helix , along with some RNA and special proteins. Bacteria or prokaryotic cells, only have one chromosome each, which is not in the nucleus.

Genes are units or factors of inheritance, each one being a length of DNA containing a particular instruction. For instance your eventual height is determined by a particular gene.

Comparison of relative efficiencies of different types of respiration:

Aerobic respiration:
C 6 H. 12 0 6 + 6O 2 > 6H 2 O + 6CO 2 + 2880 kJ
sugar + oxygen > water + carbon dioxide + energy

Anaerobic respiration with ethanol formation (alcohol fermentation):
C 6 H. 12 0 6 > 2CH 3 CH 20 H + 2CO 2 + 210 kJ
sugar > ethanol + carbon dioxide + energy

Anaerobic respiration with lactic acid formation (fermentation):
C 6 H. 12 0 6 > 2CH 3 CH(OH)COOH + 150 kJ
sugar > lactic acid + energy

For more information use the on-line glossaries for Glycolysis, ATP, Krebs Cycle en Calvyn siklus

Types of association between and among life forms:

Symbiotic - a relationship between two different species of organisms, living together in direct contact.

Mutualistic - a relationship between two symbionts that is of mutual benefit, eg lichen(which is not an individual organism but the symbiosis of cyanobacteria and a fungus).

Commensal - a symbiotic relationship which benefits the symbiont , but has no effect on the host , eg many of the bacteria living inside and on the surface of the human body.

Saprofities - absorbing nutrients from dead organic matter and decomposing it in the process, eg methanogens - an anaerobic sub-group of archaebacteria, used as decomposers for sewage treatment.

Host - participant which is exploited by the symbiont.
Symbiont - participant living in or on the host.

Microbes have many different ways of metabolizing - getting the energy they need to live, known as voeding .

Voeding means the way an organism acquires two resources - energy and carbon - with which it synthesizes organic compounds for it to function, grow, and repair itself. If the species uses light as its energy source it is called a phototroph , if it uses energy from chemicals it is a chemotroph .

Outotrofe are organisms that only require inorganic compounds such as carbon-dioxide for their source of carbon.

Heterotrophs are organisms which require at least one organic nutrient from organisms, or their by-products, as a carbon source for producing their own organic compounds.

Photoautotrophs are photosynthetic bacteria and cyanobacteria which build up carbon-dioxide and water into organic cell materials using energy from sunlight. One product of this process is starch, which is a storage or reserve form of carbon, which can be used when light conditions are too poor to satisfy the immediate needs of the organism. Photosynthetic bacteria have a substance called bacteriochlorophyll, live at the bottom of lakes and pools, and use the hydrogen from hydrogen-sulphide instead of from water, for the chemical process. (Die bacteriochlorophyll pigment absorbs light in the extreme UV and infra-red parts of the spectrum which is outside the range used by normal chlorophyll). Pers en green sulfur bacteria use light, carbon-dioxide and hydrogen-sulphide from anaerobic decay, to produce carbohydrate, sulfur and water. Sianobakterieë live in fresh water, seas, soil and lichen, and use a plant-like photosynthesis which releases oxygen as a by-product.
Sianobakterieë Lyngbia © 1997, Microbial Diversity

Photoheterotrophs use light, but obtain their carbon in organic form. Only certain types of prokaryotes can do this. The first life on Earth may have been of this type, using organic material such as amino acids not produced by biological activity.

Chemoautotrophs include many bacteria. They use special chemical processes instead of sunlight to produce organic material from inorganic. Usually compounds other than sugar are oxidized for the chemical process. Colorless sulfur bacteria which live in decaying organic matter where they are unable to use sunlight, oxidize the hydrogen-sulphide given off, to form water and sulfur. Iron bacteria, which live in streams that run over iron-rich rocks, oxidize the iron salts. Hydrogen bacteria can oxidize hydrogen with the formation of water. Nitrifying bacteria are important for enriching soil with nitrogen in a form that can be used by plants. (Sien nitrification en denitrification).

A saprophytic species of penicillium - mold on orange

Nitrification and de-nitrification: Most of the ammonia from decayed animal and plant proteins in the soil is used by bacteria such as nitrosomonasen nitrococcusas an energy source. This activity oxidizes ammonia to nitrite whereupon other bacteria, nitrobacter, oxidize the nitrite to nitrate in a process called nitrification . Nitrate released from this process can be assimilated by plants through their roots and converted to organic form such as amino acids and proteins. Animals, however, can only assimilate organic nitrogen by eating other animals or plants.

The Food Chain or Food Web: is the process by which biomass is recycled. This involves the movement or cycling of organic chemicals through the environment, ie the movement of carbon, nitrogen, oxygen and water, through plants, animals, fungi, bacteria, etc by respiration and metabolism. For the processes involved, see Cycling Chemicals and Rainforest Ecology


Nanobacteria filaments x35000
© 1999 The Centre for Microscopy and Microanalysis

How small are microbes?

Microbes are extremely small but how small? They are so small that we cannot normally see them. You could fit many thousands on this full stop .

Let us consider a typical bacterium. How big is it and what would it weigh?

It would be something like 0.003 mm long and it would weigh 0.000000000001 grams

Viruses are even smaller and recently nanobacteria a hundred times kleiner than common bacteria, have been found. At the other end of the scale, giant bacteria are known. Een, Epulopiscium fishelsoni is 0.06 mm long and 0.008 mm wide.

We use microscopes to see individual microorganisms, but it is possible to see colonies with the naked eye. Yeasts and molds are easy to see, as are the matted strands of algae. But in such instances you will be looking at thousands of individuals.


Growing Yeast: Sugar Fermentation

Yeast is most commonly used in the kitchen to make dough rise. Have you ever watched pizza crust or a loaf of bread swell in the oven? Yeast makes the dough expand. But what is yeast exactly and how does it work? Yeast strains are actually made up of living eukarioties microbes, meaning that they contain cells with nuclei. Being classified as swamme (the same kingdom as mushrooms), yeast is more closely related to you than plants! In this experiment we will be watching yeast come to life as it breaks down sugar, also known as sukrose, through a process called fermentation. Let&rsquos explore how this happens and why!

Probleem

What is sugar&rsquos effect on yeast?

Materiaal

  • 3 Clear glass cups
  • 2 Teaspoons sugar
  • Water (warm and cold)
  • 3 Small dishes
  • Permanent marker

Prosedure

  1. Fill all three dishes with about 2 inches of cold water
  2. Place your clear glasses in each dish and label them 1, 2, and 3.
  3. In glass 1, mix one teaspoon of yeast, ¼ cup of warm water, and 2 teaspoons of sugar.
  4. In glass 2, mix one teaspoon of yeast with ¼ cup of warm water.
  5. In glass 3, place one teaspoon of yeast in the glass.
  6. Observe each cups reaction. Why do you think the reactions in each glass differed from one another? Try using more of your senses to evaluate your three glasses sight, touch, hearing and smell especially!

Resultate

The warm water and sugar in glass 1 caused foaming due to fermentation.

Fermentation is a chemical process of breaking down a particular substance by bacteria, microorganisms, or in this case, yeast. The yeast in glass 1 was activated by adding warm water and sugar. The foaming results from the yeast eating the sucrose. Did glass 1 smell different? Typically, the sugar fermentation process gives off heat and/or gas as a waste product. In this experiment glass 1 gave off carbon dioxide as its waste.

Yeast microbes react different in varying environments. Had you tried to mix yeast with sugar and cold water, you would not have had the same results. The environment matters, and if the water were too hot, it would kill the yeast microorganisms. The yeast alone does not react until sugar and warm water are added and mixed to create the fermentation process. To further investigate how carbon dioxide works in this process, you can mix yeast, warm water and sugar in a bottle while attaching a balloon to the open mouth. The balloon will expand as the gas from the yeast fermentation rises.

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