Biodegradation of organophosphorus pesticide profenofos by the bacterium Bacillus sp. PF1 and elucidation of initial degradation pathway

Among the organophosphate pesticides, the wide and indiscriminate use of profenofos (PFF) in agricultural and horticultural crops has resulted in serious environmental and animal health concerns and therefore demands an urgent need to develop a biological solution for its effective removal from the environment. For the bioremediation of PFF, a strain PF1, capable of utilizing profenofos as the sole source of carbon and energy was isolated from the soil samples of apple orchards of Shimla region of Himachal Pradesh, India. Based on the biochemical, FAME, and 16S rRNA gene analysis the bacterium PF1 was identified as Bacillus altitudinis (GenBank: MH986176). The strain was able to degrade 50 mu g mL(-1) PFF up to 93% within 30 days of incubation at 28 degrees C, pH 7.0. A linear regression analysis performed on the data-set revealed the statistical significance of the relationship between the growth of the bacterial population and the degradation of pesticides. The compound 4-Bromo-2-chlorophenol (BCP) was detected as one of the pathway metabolites which further were completely degraded to lower pathway metabolites. A probable PFF degradation pathway has been proposed which follows the path from PFF to BCP and ultimately enters into the TCA cycle. To the best of our knowledge, this is the first report of PFF biodegradation by any Bacillus species of western Himalayan origin exhibiting close phylogenetic association with Bacillus altitudinis. This indigenous bacterium can be useful to bio-remediate the PFF contaminated soil as this pesticide is extensively used in the different horticulture fields in Himachal Pradesh, India.