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 CO Chemolithoautotroph 2 microbes energy works

CH2O

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 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. Glllycolysis ((lglyco + ll)ysis)

- primary central pathway for all living organisms - 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 - not require oxygen - catalyzed by enzymes - 2 mo lecu les o f ATP are inves te d an d 4 ATP are pro duce d

Glycolysis (Embden-Meyerhof)

Phase I Phase II Pentose phosphate pathway Entner-Doudoroff pathway

PdPseudomonas, Rhibi Rhizobium Chapter 8. Microbial metabolism

4. Fermen ta tion

- side step of glycolysis -> takes place in the absence of oxygen

- pyruvate is transformed into other or ganic products -> alcohol,,, acid, CO2 - Yeast : Mag-gul-li, wine Streptococcus, Lactobacillus : yogurt Fermentation Microbial fermentations

*공통특징 : -NADH는NAD+로산화 - Pyruvate나 그 유도체가 전자수용체

1: lactate 발효 - homolactic: 모든 pyruvate를 lactate로 - heterolactic: lactate 이외의 산물 생산 2: alcohol 발효 3: propionate 발효 4: butanediol 발효 5: formic acid 발효 6: acetate 발효 Chapter 8. Microbial metabolism

5. Aero bic re spira tintion

- pyruvate의 분해과정 - mitochondria 내에서 acetyl-coA로 변환 후 Krebs cycle 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, 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. Anaero bic resp ira tion

- take place under anaerobic condition - use alternatives to oxygen as an final electron acceptor 산화환원, 환원전위, 전자이동 Photosynthesis in microbes MtbliMetabolism o f o ther nu titrien ts 대사 조절 에너지대사 회로