Biodegradation of pesticides used in agricultural fields of Kerala and molecular characterization of responsible strain
Student name: Ms Sushma Shrivastava
Guide: Dr Deepti Gupta
Year of completion: 2012
Host Organisation: Unibiosys Biotech Research Laboratory
Supervisor (Host Organisation): Dr K.S. Rishad
Abstract: Pesticides are the chemical substances required to protect crops from diverse pests. Its harmful
effects like natural resource (air, water, soil) contamination and health hazards like cancer,
neurological disorders etc. are of major concerns. Several pesticides which are of banned usage
like Carbendazim, Chlorpyrifos (in U.S.) are still being used in some parts of India. Kerala was
chosen as the study area. Here non-judicious and illegal use of pesticides for agriculture has
been reported followed by its hazardous after effects. So, various agricultural fields in Kerala
viz. Kasargod, Adimali, Palakkad and Thrissur were visited for soil sample collection.
Interaction with farmers regarding pesticide handling, noticeable health hazard, knowledge of
quantitative application and relevant imparted trainings was carried out.
Simultaneously, the collected soil samples were analyzed for presence of pesticide bio-degrading
strains. Such strains for Carbendazim and Chlorpyrifos degradation were successfully isolated
from the sample collected from mixed cultivation field of Adimali (Vegetable Fruit and
Promotion Council, Kerala). The bio-degradation rate was studied with help of
spectrophotometer for both the pesticides by supplying their crude form in inoculated MSM
(Minimal Salt Media) respectively. Upper tolerance limit was also worked out individually for
both the strains. Further molecular characterization was done to identify the bio-degrading
strains by DNA isolation and 16S rRNA mediated PCR (Polymerase Chain Reaction)
amplification followed by sequencing and NCBI-BLAST (Basic Local Alignment Search Tool)
analysis. The Carbendazim and Chlorpyrifos degrading strains were identified as
Achromobacter xylosoxidans and Brevibacterium epidermidis respectively.
Pesticides along with other minerals in soil, are also uptaken by roots and accumulate in its
vegetative parts. Thus extract of various agricultural samples (fruits and vegetables) were also
tested for presence of Carbendazim and Chlorpyrifos that gave positive result for presence of
same. Isolated organisms were then preserved in 30% (v/v) glycerol solution
Keywords: Pesticide, hazardous, bio-degradation, Achromobacter xylosoxidans, Brevibacterium
epidermidis
