Post on 22-Apr-2018
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Chapter 8. Microbial metabolism
- metabolism : “metaballein” = change
- microbial metabolism : all chemical changes occurring in a microbe during its growth
and development for healthy and stable maintenanceand development for healthy and stable maintenance
- occurring for activities such as movement, growth, synthesis, foodstuff, reproduction
-> highly organized and responsive to cellular control in its local environment
-> rxn of metabolism are used efficiently, economically
Light energy Chemical energyLight energy
PhotolithoautotrophChemolithoautotroph
Chemical energy
CO2Chemolithoautotroph
CH2Oenergy worksmicrobes
Chemoorganoheterotroph(energy, biosynthesis)
Chapter 8. Microbial metabolism
1. Enzyme
- all metabolic rxns are catalyzed and regulated by enzyme- enzyme : organic molecules, catalysts
-> catalyst : speed up the rxn without being chemically transformed by itself
* Enzyme reaction
Chapter 8. Microbial metabolism* Enzyme reaction
- enzyme provide a site for substrate binding -> active site- enzyme-substrate complex is formed at transition state- end products is released
2. Energy
Chapter 8. Microbial metabolism2. Energy
- major goal of metabolism :
-> supply energy-storing substances and release when needed
(photosynthesis) vs (respiration)
- ATP : energy carrier molecule
-> adenosine triphosphate
-> universal energy currency
l l ( l l )
Chapter 8. Microbial metabolism
3. Glycolysis (glyco + lysis)
- primary central pathway for all living organisms
- starts from six-carbon organic molecule glucose- starts from six-carbon organic molecule, glucose
- produce three-carbon molecule, pyruvate, as end product
- pyruvate is utilized for three different destination
take place in the cytoplasm of microbes- take place in the cytoplasm of microbes
- not require oxygen
- catalyzed by enzymes
2 l l f ATP i t d d 4 ATP d d- 2 molecules of ATP are invested and 4 ATP are produced
4 F t ti
Chapter 8. Microbial metabolism
4. Fermentation
- side step of glycolysis -> takes place in the absence of oxygen
- pyruvate is transformed into other organic products -> alcohol, acid, CO2py g p , , 2
- Yeast : Mag-gul-li, wine Streptococcus, Lactobacillus : yogurt
Microbial fermentations
*공통특징 :공통특징 : - NADH는 NAD+로 산화- Pyruvate나 그 유도체가 전자수용체
1: lactate 발효1 lactate 발효- homolactic: 모든 pyruvate를 lactate로- heterolactic: lactate 이외의 산물 생산2: alcohol 발효3: propionate 발효3 propionate 발효4: butanediol 발효5: formic acid 발효6: acetate 발효
Chapter 8. Microbial metabolism
5 A bic spi ti n5. Aerobic respiration
- pyruvate의 분해과정
- mitochondria 내에서 acetyl-coA로 변환 후 Krebs cycle 에 투입y y
- mitochondria 없으면 세포막에서 진행
1) Krebs cycle :
- one cycle : one acetyl-coA -> two CO2
- citric acid cycle, TCA(tricarboxylic acid) cycle
- produce NADH, FADH2, ATPproduce NADH, FADH2, ATP
- intermediate products -> precursor of biosynthesis
Chapter 8. Microbial metabolism
)2) Electron transport and chemiosmosis :
- take place in mitochondria or cell membrane
serious of losses & gains of electron- serious of losses & gains of electron
between electron carrier molecules
- beginning with NADH and FADH2
- final electron acceptor : O2 ->produce H2O
- what if there is no O2 ?
- released energy is used to make proton gradient
cross the membrane
- proton gradient is utilized to synthesis ATP
산화환원, 환원전위, 전자이동산화환원, 환원전위, 전자이동
E’o(standard reduction potential) : affinity for electron+ : 전자를 받아들이는 경향이 큼- : 전자를 내어놓는 경향이 큼
Chapter 8. Microbial metabolism
☞ electron transport and chemiosmosis☞ electron transport and chemiosmosis
Chapter 8. Microbial metabolism
6 A bi i ti6. Anaerobic respiration
- take place under anaerobic condition
- use alternatives to oxygen as an final electron acceptoruse alternatives to oxygen as an final electron acceptor