Anaerobic bacteria, microbial

Anaerobic reactor A bioreactor in which no dissolved oxygen or nitrate is present and microbial activity is due to anaerobic bacteria. 

S. S. Belyaev, I. A. Charakchian, and V. G. Kuznetsova. Strict anaerobic bacteria and their possible contribution to the enhancement of oil recovery. In E. C. Donaldson, editor. Microbial enhancement of oil recovery Recent advances Proceedings of the 1990 International Conference on Microbial Enhancement of Oil Recovery, volume 31 of Developments in Petroleum Science, pages 163-172. Elsevier Science Ltd, 1991. 

Hydrogen sulfide is produced in the large intestine of mammals by metabolism of sulfhydryl proteins by anaerobic bacteria, and may compose 0-10% of intestinal gases (Beauchamp et al. 1984 EPA 1978). It is produced in the human mouth by microbial petrification (Rosenberg et al. 1991). 

A project at the University of Arizona (FEDRIP 1996) will study microbial dehalogenation of several compounds, including chloroform. A major part of the study will focus on the facultative anaerobic bacteria Shewanella putrefaciens sp., which is known to catalyze the transformation of carbon tetrachloride to chloroform and other as yet unidentified products. The organic substrates will also contain metals. It is hoped that the end-products from the biochemical treatment can be subjected to a photolytic finishing process that will completely mineralize any remaining halogenated compounds. 

Literally hundreds of complex equilibria like this can be combined to model what happens to metals in aqueous systems. Numerous speciation models exist for this application that include all of the necessary equilibrium constants. Several of these models include surface complexation reactions that take place at the particle-water interface. Unlike the partitioning of hydrophobic organic contaminants into organic carbon, metals actually form ionic and covalent bonds with surface ligands such as sulfhydryl groups on metal sulfides and oxide groups on the hydrous oxides of manganese and iron. Metals also can be biotransformed to more toxic species (e.g., conversion of elemental mercury to methyl-mercury by anaerobic bacteria), less toxic species (oxidation of tributyl tin to elemental tin), or temporarily immobilized (e.g., via microbial reduction of sulfate to sulfide, which then precipitates as an insoluble metal sulfide mineral). 

Table 3.2 Alternative Electron Acceptors (redox couple) Used by Aerobic, Facultatively Anaerobic, and Obligately Anaerobic Bacteria at Neutral pH and the Associated Microbial Processes...

Microbial testing for aerobic and anaerobic bacteria and fungi is typically conducted. Specific species searched for include ... 

Internal Sources and Atmospheric Exchange of Methane. Methane is produced by specialized groups of obligate anaerobic bacteria (22, 23). The formation of methane as a metabolic product results either from the microbial reduction of CO2 with molecular H2, or via the fermentation of acetic acid. More structurally complex substrates may also serve as electron acceptors/donors, but the end result of methanogenesis is to produce methane and CO2 as end products (23). 

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