卡马西平降解菌的筛选分离及其降解机理

药品污染物日益成为新兴污染物研究的重点,药品卡马西平因具有多种药效被广泛使用,在环境中频繁被检出,且浓度较高,不易去除,通常作为环境中药品污染状况的指示化合物。本研究从长期用于去除药品废水的曝气生物滤池中分离出一株细菌YK-6,其能以卡马西平为惟一碳源、氮源和能源生长,通过生理生化以及16S rDNA基因序列分析鉴定并命名为Pseudomonas putida YK-6。该菌株YK-6在pH为7.2、温度30℃、卡马西平初始浓度为20 mg/L、摇床振荡速率为160 r/min的生长条件下培养5 d,对卡马西平的降解率可达54.66%。菌株YK-6对卡马西平的可能降解途径为首先通过生物的氧化作用,将CBZ氧化成CBZ-EP,CBZ-EP经过水解作用转化为CBZ-DiOH,CBZ-DiOH经丙酮酸氧化脱羧及在NADH还原性辅酶的作用下,裂解成苯胺和邻苯甲酸,苯胺和邻苯甲酸再经进一步氧化,直至最终矿化。

Isolation of a bacterial strain capable of carbamazepine degrading and biodegradation mechanism

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.