bacteria that reduce sulfates with the formation of hydrogen sulfide. Among the desulfurizing bacteria are the curved, motile, nonsporiferous, and markedly anaerobic bacteria of the genus Desulfovibrio. The energy required to reduce the sulfates is obtained by the desulfurzing bacteria as a result of the oxidation of organic substances (alcohols, organic acids). In the process, the oxygen of the sulfates is the acceptor of the hydrogen electron (“respiration owing to sulfate”). The reduction of sulfates in the presence of sodium lactate proceeds as follows:
2CH3CHOHCOONa + MgSO4 → 2CH3COONa + CO2 + MgCO3 + H2S + H2O
Desulfurizing bacteria contain the enzyme hydrogenase, and therefore molecular hydrogen can also serve as a source of energy for them. Adenosine triphosphate (ATP), sulfurylase, and cytochrome c3 are involved in the reduction of sulfates. Desulfurizing bacteria live in the water and soil of water basins, in runoff waters, and in stratal waters that are rich in sulfates. As they form hydrogen sulfide, desulfurizing bacteria impart a black color to therapeutic mud and sometimes cause the destruction of fish in water basins and, under anaerobic and moist conditions, the corrosion of iron structures, pipes, petroleum equipment, and the like.
A. A. IMSHENETSKII