Biodegradation of avermectin by Bacteroidetes endosymbiont strain LYH

Avermectin fermentation wastewater was bio-refractory and the waste products could not be completely eliminated during biological treatment. In this paper, strain LYH degrading avermectin was isolated from the activated sludge of the avermectin wastewater treatment plant. It was identified as a Bacteroidetes endosymbiont by 16S rDNA sequence analysis and physio-biochemical tests, respectively. The optimal degradation conditions were as follows: temperature 30°C, pH 7.0–8.0, shaking speed 150 rev min⁻¹. The concentration of avermectin was detected by HPLC. The proposed biodegradation pathways of avermectin were given in the light of the metabolites detected, which were analysed by HPLC and the LC-MS method. These results indicated that it was feasible and potential to enhance avermectin degradation by strain LYH.