Biodegradation of N-methylated carbamates by free and immobilized cells of newly isolated strain Enterobacter cloacae strain TA7

ABSTRACT

A bacterial strain (TA7) capable of consuming three N-methylated carbamates as sole nitrogen and carbon source was isolated and identified as “Enterobacter cloacae” on the basis of 16S rRNA, from carbamate contaminated agricultural soil by enrichment culture technique. The agar entrapment was used to immobilize the bacterial cells. Both the free as well as the immobilized cells were used to study the degradation of three carbamets viz. aldicarb, carbofuran, and carbaryl. The immobilized cells degraded all the three carbamates much faster than their free cell counterparts. The biodegradation kinetics of aldicarb, carbaryl, and carbofuran was studied using 50 ppm as initial concentration in the presence of free cells. The average values of K_s for aldicarb, carbofuran, and carbaryl were 22.6, 17.87, and 8.9 mg/L, respectively, whereas the values for µ_max were calculated as 1.35, 1.3, and 1.2 mg/l/h⁻¹. The results indicated that the bacterium has high affinity towards all the three carbamates. However, relatively higher affinity is for carbaryl, in comparison with carbofuran and aldicarb. Results indicate the potential of E. Cloacae TA7 to remediate N-methylated carbamates polluted water and soil.

KEYWORDS:

• Biodegradation
• enterobacter cloacae
• immobilized cells
• kinetics
• N-methylated carbamates