Exposure to sulfide causes populations shifts in sulfate-reducing consortia

The shift in the community structure of a mixed culture of sulfate-reducing bacteria (SRB) at 0.5, 0.75, 1, and 1.5 kg m−3 sulfide loadings was investigated in an anaerobic continuous bioreactor used for treatment of sulfate-containing wastewater by fluorescence in situ hybridization (FISH), using SRB species-specific and group-specific 16S rRNA-targeting probes. Hybridization analysis using these 16S rRNA-targeted oligonucleotide probes revealed that sulfide was toxic for Desulfonema, Desulfobulbus spp. and the Desulfobacteriaceae group, although it was not toxic for Desulfobacter, Desulfotomaculum, Desulfobacterium spp. or the Desulfovibrionaceae group. On the other hand, only a high concentration of sulfide of 1.5 kg m−3 was found to be toxic for the Desulfococcus group in the bioreactor. When the sulfide in the feed was 1.00 kg m−3 the sulfate-reducing capacity of the system decreased, and this decrease was more pronounced when the inlet sulfide was further increased to 1.5 kg m−3.