Occurrence of sulfate-reducing bacteria in well water: identification of anaerobic sulfidogenic bacterial enrichment cultures.

ABSTRACT

Bacteriological studies of well water mainly focus on aerobic and facultative aerobic coliform bacteria. However, the presence of obligate anaerobic bacteria in well water, especially sulfate-reducing bacteria (SRB), possible causative agents of some diseases, is often ignored. In this study, the presence of SRB and coexisting anaerobic bacteria with SRB in sulfate-reducing enrichment cultures obtained from 10 well water samples in Istanbul was investigated. A nested polymerase chain reaction-denaturing gradient gel electrophoresis strategy was performed to characterize the bacterial community structure of the enrichments. The most probable number method was used to determine SRB number. Out of 10, SRB growth was observed in only one (10%) enrichment culture and the SRB number was low (<10 cells/mL). Community members were identified as Desulfolutivibrio sulfodismutans and Anaerosinus sp. The results show that SRB coexist with Anaerosinus sp., and this may indicate poor water quality, posing a risk to public health. Furthermore, Anaerosinus sp., found in the human intestinal tract, may be used as an alternative anaerobic fecal indicator. It is worth noting that the detection of bacteria using molecular analyzes following enrichment culture techniques can bring new perspectives to determine the possible origin and presence of alternative microbial indicators in aquatic environments.