An excellent study by Watanabe and coworkers [32”] used
a combination of molecular biological and microbiological
methods to detect and characterize the dominant phenoldegrading
bacteria in activated sludge. TGGE analysis of
PCR products of 16s rDNA and of the gene encoding phenol
hydroxylase (LmPH) showed a few dominant bacterial
populations after a 20 day incubation with phenol.
Comparison of sequences of different bacterial isolates and
excised TGGE bands revealed two dominant bacterial
strains responsible for the phenol degradation.
An integrated approach including metabolic and genetic
fingerprinting as well as conventional ecotoxicological testing
procedures was used to follow the impact of pesticide
treatment on the structure and function of bacterial soil
communities [33’]. The application of the herbicide
Herbogil showed the greatest impact on community composition
and metabolic activity. BIOLOG (a substrate
utilization assay) and TGGE analysis showed differences in
substrate utilization patterns, and in the number and intensities
of bands, respectively. The ecotoxicological testing
procedures showed a reduction of substrate-induced respiration
and dehydrogenase activity, and an increase in
nitrogen mineralization. Sequencing of excised TGGE
bands showed the phylogenetic affiliation of community
members that were most responsive to herbicide treatment.