Phenotypic and phylogenic groups to evaluate the diversity of Citrobacter isolates from activated biomass of effluent treatment plants

The diversity of Citrobacter isolated from effluent treatment plants (ETPs) was studied using three different parameters. Thirty Citrobacter strains were isolated from different ETPs treating wastewaters generated at various industries. All the isolates were characterized based on biochemical tests, antibiotic assay/functional analysis, and phylogenetic analysis. Results demonstrated that the pattern of grouping varied based on the selected criteria for analysis. Species that clustered together by biochemical analysis were found to vary by functional and 16S rDNA analysis and vice versa. This suggests that multiple methods approach needs to be carried out to understand the microbial diversity. Bacteria in effluent treatment plants are exposed to diverse categories of pollutants. Salicylate is a key intermediate formed during biodegradation of several aromatic compounds, a scenario expected in ETPs. Hence, the Citrobacter isolates were screened for their capability to utilize salicylate. In future studies, these isolates can be incorporated in a bioremediation program. (c) 2007 Elsevier Ltd. All rights reserved.