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Microbial Metabolism Metabolism of Energy Production Microbial Metabolism ••Many microorganisms have some of the same metabolic pathways as humans ••Two types of metabolism ––Anabolism: building or synthesis reactions ––Catabolism: degradation/breaking down reactions Microbial Metabolism ••Energy production metabolism ––Catabolic ––End result is ATP ––Chemoheterotrophs (humans, many microbes) ••Cellular respiration (aerobic respiration) ––Glycolysis ––Krebs Cycle (TCA or Citric acid cycle) ––Electron transport chain ––Microbes have other types of metabolism other than cellular respiration. AT P Overview Energy Metabolism of Microorganisms ••Cellular Respiration ••Anaerobic Respiration ••Fermentation ••Chemolithotrophy ••Photosynthesis ATP Production ••Metabolic Pathways for ATP Production ––Chemoheterotrophy: Cellular Respiration, Fermentation, Anaerobic respiration ••Oxidation of organic compounds (electron donor) ––Example donor: glucose ––Chemolithotrophy (chemoautotrophy) ••Oxidation of inorganic compounds (electron donor) ––Example donor: nitrite ––Phototrophy (photoautotrophy) ••Photons used to boost electrons to higher energy levels which then are transferred to lower levels to produce ATP Cellular Respiration Cellular Respiration Anaerobic Respiration ••Same as cellular respiration except: ––No oxygen used in last step of ETC ––Uses other inorganic compounds ••Nitrate (NO3-) – (nitrate reducing bacteria) ••Sulfate (SO4--) ••Others Fermentation ••Anaerobic ••Partial catabolism of carbohydrates ••Energy yield much smaller than cellular respiration ••Glycolysis present ––Only substrate level phosphorylation ––No Krebs Cycle or ETC used! ••Organic end products given off––Acids, alcohols, gasses, ketones, aldehydes ••Replenishment of NAD+ ••Needed to keep glycolysis running End Products of Fermentation ••Acids – many types ••Alcohols ––Ethanol and butanol common ••Gasses ––CO2 and H2 Fermentation Pathways Uses of Fermentation ••Food Products ––Bread ••leavening ––Alcohol ••Beer, wine ––Fermented milk products ••Yogurt ––Fermented vegetables ––Fermented meats ••Industry ––Production of alcohols Chemolithotrophy ••Only prokaryotes capable of this metabolism ••Inorganic molecules oxidized ––Nitrogen: ammonia, nitrite ––Sulfur: sulfur, sulfides, thiosulfate ––Iron: ferrous iron (Fe2+) ferric iron (Fe3+) ––Hydrogen ••Electrons from oxidation used in ETC - ATP produced ––O2 as final e- acceptor ••Not as energy efficient as cellular respiration. ••Most are autotrophs Importance of Chemolithotrophy ••Vital step in many nutrient cycles ••Nitrogen processing very important –– provides usable forms of nitrogen to higher organisms – like plants! End ••Go to : Microbial


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KSU BSCI 20021 - Lecture notes

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