Wawer et al. were the first to use DGGE analysis of [NiFe] hydrogenase gene fragments of Desulfovibrio
species, an important group of sulfate-reducing bacteria. By comparative analysis of PCR products obtained from
genomic DNA and mRNA extracted from bioreactor samples incubated with hydrogen, the substrate for the [NiFe]
hydrogenase enzyme, the authors could demonstrate the presence of different Desulfofovihio populations, but only
the preferential expression of the [NiFe] hydrogenase gene by one population. It was concluded that this population
might be better adapted to growth on hydrogen than other Desulfoovibrio populations suggesting a niche differentiation
of closely related bacterial populations performing different functions in the community. As more sequences
for other functional genes become available in the future, we will soon be able to use PCR-DGGE/TGGE to relate
community structure and function.