Isolation, Identification And Degradation Characterization Of Lambda-Cyhalothrin-Degrading Strain Bacillus Sp. GF-1

A bacterium GF-1 utilizing lambda-cyhalothrin as sole carbon source was isolated from activated sludge collected from the waste water-treating system of a pesticide manufacturer. On the basis of its morphological, physiological and 16S rDNA sequence analysis （GenBank Accession No. EU600242）, the strain was identified as Bacillus sp..The investigation of the biological characteristics of strain GF-1 showed that, the optimal pH value for the growth of strain GF-1 was 7.0, the optimal temperature was 30℃. The growth of strain GF-1 was proportionally related to aeration. The optimal NaCl concentration for the strain GF-1 was 10g/L. Organic nitrogen was optimal nitrogen source of growth. GF-1 has resistance to a few antibiotics, such as Amoxicillin, Ceftazidime and has sensitivity to Gentamici, Kanamycin, Penicillin.The optimal pH for degrading lambda-cyhalothrin by the strain GF-1 was pH7.0, the optimal temperature was 30℃. The speed of degrading lambda-cyhalothrin was related positively to initial inoculum size. The strain could degrade lambda-cyhalothrin increasingly with more oxygen. In addition of lambda-cyhalothrin GF-1 was also capable of degrading fenvalerate, cypermethrin, beta-cypermethrin, deltamelthnn, biphenthrin, cyhalothrin and so on. Plasmid curing experiment showed that plasmid of GF-1 was relative to the ability to degrade lambda-cyhalothrin.The bioremediattion of lambda-cyhalothrin-contaminated soil by GF-1 showed that degrading rates of lambda-cyhalothrin in soil was 80.73 % in 9 days, higher than that in check soil, demonstrating that GF-1 could promote the degradation of lambda-cyhalothrin in soil. The degradation rate was related positively to initial inoculation amount. In unsterilized soil, the degradation rates of f lambda-cyhalothrin by GF-1 were faster than that in sterilized soil. Various factors, including soil pH, temperature, initial lambda-cyhalothrin concentration, and inoculum size influenced its degradation efficiency. The addition of 10⁷ CFU·g^-1 was able to effciently degrade lambda-cyhalothrin at concentrations of 20～200mg·kg^-1 soil at temperature range of 20～40℃. The results indicated that strain GF-1 has potential in bioremediation of lambda-cyhalothrin-contaminated soil.