Biodegradation of cypermethrin by immobilized cells of Micrococcus sp. strain CPN 1.

Pyrethroid pesticide cypermethrin is a environmental pollutant because of its widespread use, toxicity and persistence. Biodegradation of such chemicals by microorganisms may provide an cost-effective method for their detoxification. We have investigated the degradation of cypermethrin by immobilized cells of Micrococcus sp. strain CPN 1 in various matrices such as, polyurethane foam (PUF), polyacrylamide, sodium alginate and agar. The optimum temperature and pH for the degradation of cypermethrin by immobilized cells of Micrococcus sp. were found to be 30 °C and 7.0, respectively. The rate of degradation of 10 and 20 mM of cypermethrin by freely suspended cells were compared with that of immobilized cells in batches and semi-continuous with shaken cultures. PUF-immobilized cells showed higher degradation of cypermethrin (10 mM and 20 mM) than freely suspended cells and cells immobilized in other matrices. The PUF-immobilized cells of Micrococcus sp. strain CPN 1 were retain their degradation capacity. Thus, they can be reused for more than 32 cycles, without losing their degradation capacity. Hence, the PUF-immobilized cells of Micrococcus sp. could potentially be used in the bioremediation of cypermethrin contaminated water.

Biodegradation of cypermethrin by immobilized cells of Micrococcus sp. strain CPN 1

Pyrethroid pesticide cypermethrin is a environmental pollutant because of its widespread use, toxicity and persistence. Biodegradation of such chemicals by microorganisms may provide an cost-effective method for their detoxification. We have investigated the degradation of cypermethrin by immobilized cells of Micrococcus sp. strain CPN 1 in various matrices such as, polyurethane foam (PUF), polyacrylamide, sodium alginate and agar. The optimum temperature and pH for the degradation of cypermethrin by immobilized cells of Micrococcus sp. were found to be 30 °C and 7.0, respectively. The rate of degradation of 10 and 20 mM of cypermethrin by freely suspended cells were compared with that of immobilized cells in batches and semi-continuous with shaken cultures. PUF-immobilized cells showed higher degradation of cypermethrin (10 mM and 20 mM) than freely suspended cells and cells immobilized in other matrices. The PUF-immobilized cells of Micrococcus sp. strain CPN 1 were retain their degradation capacity. Thus, they can be reused for more than 32 cycles, without losing their degradation capacity. Hence, the PUF-immobilized cells of Micrococcus sp. could potentially be used in the bioremediation of cypermethrin contaminated water.

Bacterial degradation of fungicide captan.

The phthalimide fungicide captan has been widely used to control plant pathogenic fungi. A strain of Bacillus circulans utilized the fungicide captan as sole source of carbon and energy. The organism degraded captan by a pathway involving its initial hydrolysis to yield cis-1,2,3,6-tetrahydrophthalimide, a compound without fungicidal activity. The formation of this compound was confirmed by HPLC, IR, NMR, and mass spectral analysis. The results also revealed that cis-1,2,3,6-tetrahydrophthalimide was further degraded to o-phthalic acid by a protocatechuate pathway. These findings indicated that there was a complete mineralization of fungicide captan by B. circulans.

Biodegradation of cypermethrin by Micrococcus sp. strain CPN 1.

A bacterium capable of utilizing pyrethroid pesticide cypermethrin as sole source of carbon was isolated from soil and identified as a Micrococcus sp. The organism also utilized fenvalerate, deltamethrin, perimethrin, 3-phenoxybenzoate, phenol, protocatechuate and catechol as growth substrates. The organism degraded cypermethrin by hydrolysis of ester linkage to yield 3-phenoxybenzoate, leading to loss of its insecticidal activity. 3-Phenoxybenzoate was further metabolized by diphenyl ether cleavage to yield protocatechuate and phenol as evidenced by isolation and identification of metabolites and enzyme activities in the cell-free extracts. Protocatechuate and phenol were oxidized by ortho-cleavage pathway. Thus, the organism was versatile in detoxification and complete mineralization of pyrethroid cypermethrin.