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 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 energy
Photolithoautotroph
Chemolithoautotroph
microbes
CO2
energy
CH2O
Chemoorganoheterotroph
(energy, biosynthesis)
works
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
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
Chapter 8. Microbial metabolism
☞ enzyme-substrate complex
Chapter 8. Microbial metabolism
2. 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
Chapter 8. Microbial metabolism
3. Glycolysis
l
l
(glyco
( l
+ lysis)
l
)
-
primary central pathway for all living organisms
starts from six-carbon organic molecule
molecule, glucose
produce three-carbon molecule, pyruvate, as end product
pyruvate is utilized for three different destination
take place in the cytoplasm of microbes
not require oxygen
catalyzed by enzymes
2 molecules
l
l off ATP are iinvested
t d and
d 4 ATP are produced
d
d
Glycolysis (Embden-Meyerhof)
Phase I
Phase II
Pentose phosphate pathway
Entner-Doudoroff pathway
P
Pseudomonas,
d
Rhi
Rhizobium
bi
Chapter 8. Microbial metabolism
4 F
4.
Fermentation
t ti
- side step of glycolysis -> takes place in the absence of oxygen
- py
pyruvate is transformed into other organic
g
p
products -> alcohol,, acid,, CO2
- Yeast : Mag-gul-li, wine Streptococcus, Lactobacillus : yogurt
Fermentation
Microbial fermentations
*공통특징
공통특징 :
- NADH는 NAD+로 산화
- Pyruvate나 그 유도체가 전자수용체
1 lactate 발효
1:
- homolactic: 모든 pyruvate를 lactate로
- heterolactic: lactate 이외의 산물 생산
2: alcohol 발효
3: propionate 발효
3
4: butanediol 발효
5: formic acid 발효
6: acetate 발효
Chapter 8. Microbial metabolism
5 A
5.
Aerobic
bic respiration
spi ti n
- pyruvate의 분해과정
- mitochondria 내에서 acetyl-coA로
y
변환 후 Krebs cycle
y
에 투입
- mitochondria 없으면 세포막에서 진행
1) Krebs cycle :
- one cycle : one acetyl-coA -> two CO2
- citric acid cycle, TCA(tricarboxylic acid) cycle
- produce 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
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, 전자이동
E’o(standard reduction potential) : affinity for electron
+ : 전자를 받아들이는 경향이 큼
- : 전자를 내어놓는 경향이 큼
Chapter 8. Microbial metabolism
☞ energy level of electron carriers
Chapter 8. Microbial metabolism
☞ electron transport and chemiosmosis
Chapter 8. Microbial metabolism
3) ATP synthetase
Chapter 8. Microbial metabolism
☞ Total ATP production during aerobic respiration
Chapter 8. Microbial metabolism
6 A
6.
Anaerobic
bi respiration
i ti
- take place under anaerobic condition
- use alternatives to oxygen as an final electron acceptor
산화환원, 환원전위, 전자이동
Photosynthesis in microbes
M t b li
Metabolism
off other
th nutrients
ti t
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