Study of the "sulfur-turf": a community of colorless sulfur bacteria growing in hot spring effluent.

Abstract

Sulfur-turf is one of the so-called “sulfureta” which are massive aggregates of colorless sulfur bacteria. Interest in the ecological and physiological aspects of the sulfuretum has strongly increased not only due to the discovery of massive occurrence of colorless sulfur bacteria in an area of hydrothermal vents but also due to the possibility of its significant contribution to the sulfur cycle in the coastal region. Here, I review the types, habitats, and bacterial constituents of the sulfur-turf, and further, reveal the microaerophilic oxidation of elemental sulfur by the sulfur-turf and discuss the possibility of the detoxification of hydrogen sulfide with peroxides. The habitat of the sulfur-turf is regarded as a thermostating, continuous culture enriched with hydrogen sulfide. The massive aggregates including the sulfur-turf are very useful, because they can be harvested directly from their habitats without the need for isolation and mass cultivation. Taking advantage of these massive aggregates, we should design experiments in situ and also in the laboratory to clarify the ecology and physiology of the colorless sulfur bacteria. It is necessary to elucidate the microenvironment caused by bacterial aggregation using microelectrodes, but, on the other hand, more interest should be focused on the bacterial reaction to environmental factors, especially oxygen tension.