The extensive use of pesticides in agricultural fields for pest control pose a serious problem in contaminating soil and water ecosystems. Chlorpyrifos is the major broad spectrum organophosphorus insecticide used in paddy fields against sucking, chewing, boring insects. Due to its toxicity and persistence in the environment, there is an immediate need to eliminate them from contaminated sites by biodegradation. Two pesticide degrading bacteria were screened and isolated from chlorpyrifos contaminated soil by enrichment culture technique and were identified as Kocuria kristinae and Staphylococcus aureus. The growth response and degradation of chlorpyrifos by the isolates in MSM broth supplemented with 0.5% chlorpyrifos was monitored every 48-72 hrs in spectrophotometer at 600nm. Kocuria sp showed maximum growth in 7 days than Staphylococcus aureus. The degradation efficiency of the strains were determined and estimated by the removal percentage of chlorpyrifos from the liquid culture. Both the isolate showed the degrading capability of chlorpyrifos in MSM. The isolate, S. aureus was more potent in degrading the 80% of the total compound from the media in 2 weeks of incubation than K. kristinae which shows 35 % of degradation. These results were further confirmed by GCMS, in which S. aureus has degraded 82.06% and K. kristinae has degraded 30.78% of chlorpyrifos in the medium. This study indicates that the isolate, Staphylococcus aureus is more potent in degrading chlorpyrifos in liquid culture and can also be used in bioremediation of chlorpyrifos contaminated soils.

Mosquito larvicidal activity and antimicrobial screening of ethyl acetate extract of leaves and root of Melia dubia belongs to the family of Meliaceae have been evaluated in the present study. Exposure of the larvae to these extracts for 12 hours led to 98 and 96% mortality, respectively. The results obtained show that this plant material exhibited significant activity and could be considered as potent natural larvicidal agent. The results of in-vitro antimicrobial screening of the crude ethyl acetate extract exhibited a wide range of activity on E.coli, Salmonella typhi, S. paratyphi, Klebsilla penemonia, Staphylococcus aureus. The extracts of the leaves and root inhibited the growth of K. pneumonia, E. coli and Staphylococcus aureus while only the leaf extract was active against S. typhi and S. paratyphi. The results obtained in this present study have lent scientific justification to some of the uses of the plant in ethno-medicine.