MICROBIAL RESPIRATION

MICROBIAL RESPIRATION

• After Glucose has been broken down to Pyruvic acid, the Pyruvic acid can be channeled into the next step of either Fermentation or Cellular respiration.
• Cellular respiration or simply Respiration, is defined as an ATP - generating process in which molecules are oxidized and the final electron acceptor is (almost always) an inorganic molecule.
• An essential feature of respiration is the operation of an Electron transport chain.
• There are two types of respiration. They are (i) Aerobe or Aerobic respiration (which uses oxygen) and (ii) Anaerobe or Anaerobic respiration (which does not use oxygen and may even be killed by it).
• In Aerobic respiration, the final electron acceptor is O₂ but in Anaerobic respiration, the final electron acceptor is an inorganic molecule other than O₂ or, rarely, an organic molecule
• Some of the reaction which were carried out under Aerobic respiration are Fermentation, ATP Generation (Substrate level phosphorylation, Oxidative Phosphorylation, Electron Transport Chain and Photophosphorylation), Glycolysis, Phosphoketolase pathway, Pentose phosphate pathway,  ED pathway and Kreb’s cycle.

Some Electron acceptors used in respiration are

Respiration	Electron acceptor	Reduced products	Examples of microorganisms
Aerobic	Oxygen (O2)	Water (H2O)	All aerobic bacteria, Fungi, Algae and Protozoa.
Anaerobic	Nitrite (NO3)	Nitrogen dioxide (NO2)	Enteric bacteria
	Nitrite (NO3)	Nitrogen dioxide (NO2), Nitrous oxide (N2O) and Nitrogen (N2)	Denitrification – Pseudomonas denitrificans, Bacillus sp. and Paracoccus sp.
	Sulfate (SO4)	Sulfur (S) or Hydrogen sulfide (H2S)	Sulphate Reduction - Desulfovibrio sp. and Desulfotomaculum sp.
	Carbon dioxide (CO2)	Methane (CH4)	Methanogenesis - All Methanogens and Acetogenes
	Sulfur (S)	Hydrogen sulfide (H2S)	Desulfomonas sp. and Thermoproteus sp.
	Ferric ions (Fe3+)	Ferrous ions (Fe2+)	Pseudomonas sp., Bacillus sp. and Geobacter sp.
	Hydrogen Arsenate (HAsO4)	Arsonite (HAsO2)	Bacillus sp., Desulfotomaculum sp. and Sulfurospirillum sp.
	Selenate (SeO4)	Selenium (Se) and Hydrogen selenite (HSeO3)	Aeromonas sp., Bacillus sp. and Thauera sp.
	Fumarate	Succinate	Wolinella sp.