MICROBIOLOGIA GENERALE Microbial metabolisms 1

Microbial metabolism catabolism: aims and products

High energy compounds and energy storage

Structure of the oxidation–reduction coenzyme nicotinamide adenine dinucleotide (NAD + )

Microbial metabolism energy conservation: options

Energy classes of Microorganisms Phototrophs Chemotrophs Chemoorganotrophs Chemolithotrophs Carbon source classes of Microorganisms Autotrophs Eterotrophs

Metabolic options for obtaining energy

GroupRelationship to O 2 Type of metabolism Example AEROBES Obligate RequiredAerobic respiration Micrococcus luteus Facultative Not required, growth better with O2 Aerobic respiration or Fermentation Esherichia coli MicroaerophilicRequired at low levels Aerobic respiration Spirillum volutans ANAEROBES Aerotolerant Not required, growth no better with O2 FermentationStreptococcus pyogenes Obligate Harmful or lethalFermentation or Anaerobic respiration Clostridium tetani

Metabolisme - donore - acceptorMicroorganisms Fermentation Organic molecules Organic molecule Obligately anaerobic and facultative chemoorganotrophic Aerobic Respiration Organic molecules Inorganic molecules O2O2O2O2 Obligately aerobic and facultative chemoorganotrophic Chemolithotrophs Anaerobic Respiration Organic or inorganic molecules NO 3 SO 4 CO 2 Nitrate reducers Sulfate reducers Methanogenic Photosynthesis H 2 0, H 2 S, S, organic molecules NADP NADPH Cyanobacteria, Green and Purple bacteria

Microbial metabolism fermentation

Metabolisme - donore - acceptorMicroorganisms Fermentation Organic molecules Organic molecule Obligately anaerobic and facultative chemoorganotrophic Aerobic Respiration Organic molecules Inorganic molecules O2O2O2O2 Obligately aerobic and facultative chemoorganotrophic Chemolithotrophs Anaerobic Respiration Organic or inorganic molecules NO 3 SO 4 CO 2 Nitrate reducers Sulfate reducers Methanogenic Photosynthesis H 2 0, H 2 S, S, organic molecules NADP NADPH Cyanobacteria, Green and Purple bacteria

Overall process of FERMENTATION In a typical fermentation, most of the carbon is excreted as a partially reduced end product of energy metabolism and only a small amount is used in biosynthesis

Pyruvate Pentose phosphate Shunt hexose monophosphate heterofermentative lactic acid bacteria Glycolysis enteric bacteria and homofermentative lactic acid bacteria Enter-Doudoroff Pseudomonas Rhizobium The glucose catabolism

Embden-Meyerhof pathway (glycolysis)

The catalytic cycle of the enzyme fructose bisphosphate aldolase

Pyruvate Propionic acid Propionibacterium Alcohol Saccharomyces 2,3-Butanediol Enterobacter Butyric acid Clostridium Lactic acid Homofermentative Lactic acid bacteria Mixed Acids Escherichia

Alcohol Saccharomyces Lactic acid Homofermentative Lactic acid bacteria

Homolactic fermentation (Streptococcus, Lactococcus)

Butyric acid fermentation (Clostridium)

Propionic acid fermentation The formation of propionic acid by Propionibacterium

Mixed acids fermentation (Escherichia, Salmonella, Shigella)

2,3-Butanediol fermentation (Enterobacter, Klebsiella, Serratia)

2,3-Butanediol fermentation

The Entner-Doudoroff pathway (Pseudomonas, Rhizobium)

Heterolactic fermentation (Leuconostoc, Lactobacillus)

Coupled oxidation-reduction between Ala and Gly in Clostridium sporogenes

Microbial metabolism aerobic respiration in chemoorganotrophs

Metabolisme - donore - acceptorMicroorganisms Fermentation Organic molecules Organic molecule Obligately anaerobic and facultative chemoorganotrophic Aerobic Respiration Organic molecules Inorganic molecules O2O2O2O2 Obligately aerobic and facultative chemoorganotrophic Chemolithotrophs Anaerobic Respiration Organic or inorganic molecules NO 3 SO 4 CO 2 Nitrate reducers Sulfate reducers Methanogenic Photosynthesis H 2 0, H 2 S, S, organic molecules NADP NADPH Cyanobacteria, Green and Purple bacteria

Energetics and carbon flow in chemoorganotrophic respiratory metabolism

Energy conservation in fermentation and respiration

Electron transport chains and their relation to E 0 ’. An electron transport system,leads to the transfer of electrons from substrate to O 2

Generation of the proton motive force during aerobic respiration and the orientation of key electron carriers in the membrane

Flavin mononucleotide (FMN) (riboflavin phosphate, a hydrogen atom carrier)

Arrangement of the iron sulfur centers of nonheme iron- sulfur proteins that carry electrons only Fe 2 S 2 center Fe 4 S 4 center

Structure of oxidized and reduced forms of coenzyme Q, a quinone

Cytochrome and its structure

Structure and function of ATP synthase (ATPase)

Structure and function of ATP synthase (ATPase)

Aerobic respiration of organic substrates in prokaryotes Citric acid cycle Pyruvate Carbohydrates Amino acids Fatty acids Acetyl-CoA

The citric acid cycle (CAC)

The overall balance of the aerobic respiration Alcohol fermentation 2 ATP per glucose

The overall balance of the aerobic respiration