International Journal of Environmental Bioremediation & Biodegradation. 2014, 2(5), 220-227DOI:
Abstract: Pesticides use has been one of the major factors in improving productivity in agricultural enterprises in Kenya. Phenylurea herbicides are one of the main categories of crop protection products that kill weeds and other plants that grow where they are unwanted. In recent years researchers have been paying greater attention to this family of herbicides because of their high biotoxicity and possible carcinogenic properties and lengthy periods of time for their removal from the environment. However, systematic studies on microbial removal of these pesticide residues are scarce in developing countries including Kenya. A survey in four horticultural regions of central and rift-valley Kenya showed that out of the twenty two (22) formulations of pesticides used linuron had the highest frequency of application at 45.9%. Through enrichment and isolation a total of six isolates were obtained from linuron contaminated soils. Degradation kinetics of the pesticides residues was monitored by High pressure liquid chromatography (HPLC). Level of degradation was scored by the data fit with a linear regression by the line y =49508x with an R2 value of 0.9831. The corroboration of various degradation intermediate metabolites was aided by GC-MS machine. The identified metabolites from linuron were 3, 4 dichloroanilline, 3,-chloroanalline, 4-chloroanalline N, O dimethylhydroxylamine, and N-methyl-N-methoxy carbamic acid methyl ester. Isolates designated LoG-8A, Lwa-2A, Lsh-6B, LJk-5C, Lla-1A and Lwa-2C showed the ability to degrade 70.7- 98.9% of 50mgl-1 of linuron within 84 days. Morphological, biochemical and 16S rRNA sequence analysis of these isolates indentified them with the genus Pseudomonas, Stenotrophomanas, Burkholderia, Lysinibacillus, Arthrobacter and Flavobacteria. The study demonstrated that soils from horticultural farms in Kenya harbor biodegrades for linuron. Further work can show whether these microbes can be used for the development of bioremediation strategy.