Isolation, identification and optimization of degradation conditions of a deltamethrin degrading strain

Abstract:

[Background] The degradation of pyrethroid pesticides is important for food safety and environmental health, and biodegradation is considered to be a green effective solution. [Objective] The strain with high ability to degrade deltamethrin (DM) was isolated from strawberry rhizosphere contaminated soil by pyrethroid pesticides for a long term, and the degradation rate of DM degrading strain was improved by optimizing the medium and degradation conditions. [Methods] DM degrading strain was screened by enrichment domestication, isolation, purification and identified by morphological, physio-biochemical, 16S rRNA sequence analysis. The degradation conditions were optimized by Plackett-Burman design, steepest ascent path design and Box-Behnken design. [Results] Strain LH-1-1 was identified as Acinetobacter junii, it could degrade 53.43% DM (100 mg/L) within 96 h in initial conditions. The optimized conditions were DM concentration 75 mg/L, tryptone 3 g/L, pH 6.8, (NH4)2SO4 1.5 g/L, FeCl3 0.01 g/L, inoculation biomass 5%, strain age 12 h, culture temperature 30 °C. The degradation rate of DM under these conditions reached 82.36% within 96 h, which was 28.93% higher than initial conditions. [Conclusion] A. junii LH-1-1, a highly efficient DM degrading strain, can be used as excellent microbial resources for bioremediation of environment polluted by DM or pyrethroid pesticides.

Key words:Deltamethrin, Plackett-Burman design, Box-Behnken design, Acinetobacter junii LH-1-1