Isolation, Screening and Identification of Bacteria Capable of Degrading Chlorpyrifos and Endosulfan

Soil samples rich in pesticides were collected from agricultural fields in and around Bangalore. Samples were inoculated into mineral salts medium with chlorpyrifos and endosulfan as the sole source of carbon and incubated for 90 days. Intermittent addition of pesticide was carried out for enrichment of cultures. Bacteria capable of degrading chlorpyrifos and Endosulfan were isolated on mineral salts agar medium. Out of 27 samples collected, 58 isolates capable of degrading chlorpyrifos and 68 isolates capable of degrading endosulfan were obtained, majority of them being gram negative in nature. Out of these 23 isolates for chlorpyrifos and 28 isolates for endosulfan were capable of showing good growth in mineral salts medium. Out of the 23 isolates for chlorpyrifos, 10 isolates and out of 28 isolates for endosulfan, 7 isolates were able to show evident colour change on medium with phenol red. Screening of the isolates for their efficiencies in degrading chlorpyrifos and endosulfan was carried out based on spectrophotometric analysis. Strains CHS23 and ENS10, showed the highest degradation of 38% and 42% respectively. CHS23 and ENS10 were identified as Pseudomonas putida and Pseudomonas aeruginosa respectively based on nucleotide sequence and phylogenetic tree analysis. Nucleotide sequences of Pseudomonas putida and Pseudomonas aeruginosa were deposited in NCBI gene bank with accession numbers JQ701740 and JX204836 respectively