1997 Volume 63 Issue 1 Pages 99-104
To obtain more basic and detail information on the ecology of marine sulfate-reducing bacterial population, we studied the use of in situ hybridization with 16S rRNA probes for their cellular level detection from natural environments. SRB probe was found to have wide specificity to sulfate-reducing bacterial groups. SRB probe hybridizes also with most species of δ-group of purple bacteria. However, most of them were found not to dominate in the coastal and estuarine environments. Although two species, Clostridium novyi and Myxococcus xanthus, have same sequences with SRB probe, they can be eliminated through observation under fluorescent microscope with having endospore and autofluorescence, respectively. Desulfobacter probe was found to be specific to genus Desulfobacter. We modified dual staining method of Hicks et al. (1992) with SRB probe, and compared the numbers of sulfatereducing bacteria enumerated by the present method with conventional MPN method (medium containing sodium lactate) using microcosm of zooplankton decomposition. The numbers (4.5×106-2.7×107/ml) detected using in situ hybridization with SRB probe were about two orders of magnitude higher than MPN method (1.1×103-1.5×105/ml).