Santcgoeds et al. combined molecular techniques and microsensors to study the presence and activity of sulfate-reducing bacteria in biofilms from an activated sludge basin of a wastewater treatment plant. Microsensor measurements indicated that anaerobic zones developcd within one week of biofilm formation, but that sulfate reduction did not occur until after six weeks. Hybridization analysis of 16s rDNA DGGE profiles showed that Desulfobulbus and Desulfovibrio populations
were the main sulfate-reducing bacteria, and that different populations came up at the onset of the sulfate reduction.