Diversity of 4-Chloro-2-nitrophenol-Degrading Bacteria in a Waste Water Sample

Eighteen bacterial strains, isolated from a waste water sample collected from a chemically contaminated site, Patancheru (17°32′N 78°16′E/17.53°N 78.27°E), India, were able to decolorize 4-chloro-2-nitrophenol (4C2NP) in the presence of an additional carbon source. These eighteen 4C2NP-decolorizing strains have been identified as members of four different genera, including Bacillus , Paenibacillus , Pseudomonas , and Leuconostoc based on the 16S rRNA gene sequencing and phylogenetic analysis. Most of the bacteria (10) belonged to the genus Bacillus and contributed 56% of the total 4C2NP-degrading bacteria, whereas the members of genera Paenibacillus and Pseudomonas represented 22% and 17%, respectively, of total 4C2NP-degrading isolates. There was only one species of Leuconostoc capable of degrading 4C2NP. This is the first report of the diversity of 4C2NP-decolorizing bacteria in a waste water sample. Furthermore, one bacterium, Bacillus aryabhattai strain PC-7, was able to decolorize 4C2NP up to a concentration of 2.0 mM. Gas chromatography-mass spectrometry analysis identified 5-chloro-2-methylbenzoxazole as the final product of 4C2NP decolorization in strain PC-7.