A rapid and miniaturized method for the selection of microbial phenol degraders using colourimetric microtitration.

A high-throughput method is described, consisting of a colourimetric microtitration for screening phenol-degrading microorganisms, using a mixture of 4-aminoantipyrine and potassium ferricyanide as the colour indicator. This contemporary study summarizes a new method to determine phenol-degrading bacteria isolated from different areas. The method was used for testing a total of 72 bacteria collected from the natural environment and five known strains obtained from diagnostic and research laboratories employing 200 mg/L phenol (the linear range saturation concentration). Depending on the change in colour indicator, the degradation profiles of 11 strains of bacteria are shown, of which seven strains were able to degrade more than 80 % of phenol within 6-8 h, while the other four strains took 12-24 h. Two of the environmentally isolated strains showed high efficiency of phenol degradation and were confirmed by the high-performance liquid chromatography analysis. These strains were identified by 16S rRNA sequencing as unique (Escherichia coli moh1 and Bacillus cereus moh2) and were deposited in the GenBank of NCBI. Two pathogenic strains (Uropathogenic E. coli and Salmonella sp.) were found to be the fast degraders of phenol, which is of medical concern, as phenol is generally used as a disinfectant in hospitals. This method can be used for the estimation and screening of phenol degraders in a single step, for its application in bioremediation as well as in hospitals for screening the phenol resistance of pathogens.