Production of elemental sulfur by green and purple sulfur bacteria
Van Gemerden, H.
Archives of Microbiology 146(1): 52-56
1986
ISSN/ISBN: 0302-8933 DOI: 10.1007/bf00690158
Accession: 006191614
The utilization of sulfide by phototrophic sulfur bacteria temporarily results in the accumulation of elemental sulfur. In the green sulfur bacteria (Chlorobiaceae), the sulfur is deposited outside the cells, whereas in the purple sulfur bacteria (Chromatiaceae) sulfur is found intracellularly. Consequently in the latter case, sulfur is unattainable for other individuals. Attempts were made to analyze the impact of the formation of extracellular elemental sulfur compared to the deposition of intracellular sulfur. According to the theory of the continuous cultivation of microorganisms, the steady-state concentration of the limiting substrate is unaffected by the reservoir concentration (SR). It was observed in sulfide-limited continuous cultures of Chlorobium limicola f. thiosulfatophilum that higher SR values not only resulted in higher steady-state population densities, but also in increased steady-state concentrations of elemental sulfur. Similar phenomena were observed in sulfide-limited cultures of Chromatium vinosum. It was concluded that the elemental sulfur produced by Chlorobium, although being deposited extracellularly, is not easily available for other individuals, and apparently remains (in part) attached to the cells. The ecological significance of the data is discussed.