ABSTRACT
The wide use of carbamate pesticides in agriculture has persuaded the rapid evolution and dissemination of specific degradative pathways for the compound in soil bacteria. Carbamate insecticide, carbaryl (1-naphthyl-Nmethylcarbamate), is highly toxic with a wide range of activity and known to be metabolized by microorganisms belonging to a variety of bacterial genera by interacting with different components, thereby impairing the physiological and metabolic activities of the cell. To evaluate its toxicity, the present study was undertaken by using increasing concentrations of carbaryl (10-8 to 10-2M) and evaluated for its toxicity to Escherichia coli with emphasis on biochemical contents such as DNA, RNA, protein, glucose utilization, growth and was further compared to the soil isolate- Pseudomonas aeruginosa at a given periods of 24 -72 hrs respectively. The results indicated that carbaryl treated groups exhibited a significant (P ≤ 0.05) decrease in the levels of biochemical contents and increase in the % inhibition in these parameters was observed with an increase in dose and durational exposure to carbaryl when compared to the controls. While, in assessment with its free corresponding, the activity was less in immobilized Escherichia coli cells enlightening that immobilized system is less responsive to carbaryl. Present study suggested that carbaryl is a toxicant affecting the synthesis of biochemical contents and growth in a dose and dependent manner and alterations in the parameters of Escherichia coli and Pseudomonas aeruginosa on exposure to carbaryl are can be due to carbaryl intoxication.