Studies on assimilation of free carbonic acid by purple sulfur bacteria in the lake Belovod
Mikrobiologiia 26(1): 92-98
ISSN/ISBN: 0026-3656 PMID: 13440598 Accession: 068786656
In 1954 a study was conducted on the ecology of purple sulfobacteria (PS) in Lake Beloved (Vladimir region), which is characterized by PS mass production from the genus Chromatium (Up to 170-000 cells per ml) at a depth of 12-13 m, where the border of oxygen and hydrosulfite zones is located. By exposing light and dark flasks with cultures of Scenedesmus it was established that photosynthesis in the lake is possible up to a depth of 17 m. At a depth of 13-14 m the PS have a sufficient amount of light and H2S. Laboratory experiments with a cumulative culture of PS (Rhodothece pendens Mol.) in light and dark flasks to which Na2Cl4O3 was added showed that chemosynthesis is absent. In lake conditions is was established by experiments with labeled carbon that the quantity of CO2 fixed by PS attains up to 1.15 mg/1 per day. Fixation of CO2 in the lake due to chemosynthesis accomplished by sulfur bacteria is as much as 0.4 mg/1. Thus the zone of maximum development of PS in the lake is determined by the fact that higher up there is no H2S, while below 13-14 m the light intensity is insufficient for a photosynthetic process.