Isolation of a bacterial strain capable of carbamazepine degrading and biodegradation mechanism
卡马西平降解菌的筛选分离及其降解机理

Quite recently,among new emerging contaminants,pharmaceutical products and their active metabolites are an emerging environmental issue,due to their presence in the aquatic environment and potential for impacts on wildlife and humans.Carbamazepine was one of the most frequently detected pharmaceuticals in surface water and even in drinking water and at the relatively high concentration levels.Moreover,this drug has displayed high chronic ecotoxicity.A strain of carbamazepine-degrading bacterium was isolated from biological aerated filter treating pharmaceutical wastewater.It was identified as Pseudomonas putida YK-6,based on biochemical test,16S rRNA gene sequence analysis.Strain YK-6 could grow in liquid mineral salt medium with carbamazepine as sole source of carbon,nitrogen and energy.HPLC analysis revealed that the carbamazepine degradation rate by YK-6 after 5 days was 54.66% at pH 7.2,30℃,initial carbamazepine concentration of 20 mg/L and oscillation rate of 160 r/min.Possible degradation pathway of carbamazepine by strain YK-6 was the biological oxidation.The CBZ was oxidized into CBZ-EP,and then CBZ-EP was converted to CBZ-DiOH through the hydrolysis.CBZ-DiOH was cracked into aniline and o-benzoic acid through oxidative decarboxylation by pyruvate and under the reducing the role of coenzyme NADH,and then the late one was further oxidized until the final mineralization.