Abstract

Bacteria were isolated by enrichment culture technique from groundnut (Arachis hypogaea L.) soils and tested for their ability to degrade monocrotophos in mineral salts medium under aerobic conditions in the laboratory. Based on some of the morphological and 16S rRNA gene sequence analysis, the isolates were identified as Rhodococcus phenolicus strain MCP1 and Rhodococcus ruber strain MCP-2. The initial (0-day) recovery of monocrotophos in the culture medium was 94%; and by the end of 4th day, about 21% of added monocrotophos was lost from the uninoculated medium. By the end of 1st, 2nd, 3rd and 4th day 13, 20, 24, 30% and 18, 33, 37, 45% of monocrotophos was degraded, by R. phenolicus strain MCP1 and R. ruber strain MCP-2 respectively, when the mineral salts medium was supplemented with monocrotophos as a C source. Simultaneously 12, 22, 26, 30% and 18, 26, 37, 40% of N-methylacetoacetamide a metabolite of monocrotophos was recovered in the media inoculated with the R. phenolicus strain MCP1 and R. ruber strain MCP-2 respectively, during the same period. Decrease in the amount of monocrotophos with a concomitant increase in the level of N-methylacetoacetamide clearly indicates the degradation of parent compound.

Key words: Monocrotophos; N-methylacetoacetamide, biodegradation; isolation, identification.