一株降解恩诺沙星菌株的筛选鉴定及其降解条件的优化

Screening and Identification of Enrofloxacin Degrading Strain and Optimization of Its Degradation Conditions

从长期处理含恩诺沙星猪粪的黑水虻肠道中,筛选出可降解恩诺沙星的菌株,并对菌株降解过程中的环境因素进行优化,获得较优的降解条件,为研究恩诺沙星生物降解的途径提供理论基础。将黑水虻肠液加入含有恩诺沙星的培养基中培养,经过两次筛选,从若干株具有降解恩诺沙星能力的菌种中挑选降解能力最强的一株菌株,通过单因素实验确定该菌株最适降解条件:温度、初始pH、接种量、摇床转速,根据单因素实验结果运用响应面分析得出最佳降解条件。结果表明,初筛获得17株对恩诺沙星具有降解作用的菌株,在进一步复筛中发现3株能以恩诺沙星为唯一碳源的菌株,对三株进行分子生物学鉴定,鉴定BSFL-1和BSFL-3为粪肠球菌(Enterococcus faecalis)和BSFL-2为奇异变形杆菌(Proteus mirabilis)。其中降解率最高的菌株为BSFL-3。经响应面分析各因素交互作用后,最佳降解条件为:温度33.6℃、初始pH5.8、接种量为4%、摇床转速155 r/min。在此条件下,恩诺沙星的降解率为77.83%±0.53%。降解条件优化后的菌株具有较高的降解率,拓宽了生物法降解恩诺沙星的研究领域,为利用细菌降解率恩诺沙星应用研究提供帮助。

In order to study the biodegradation of enrofloxacin,a strain was screened from the the gut of black soldier fly,which had been used to treat the pig manure containing enrofloxacin for a long time.The intestinal juice of black soldier fly was cultured in the medium containing enrofloxacin.After twice screening,the strain with the strongest ability to degrade enrofloxacin was selected from several strains with the ability to degrade enrofloxacin.The optimal degradation conditions were determined by single factor experiment:Temperature,initial pH,inoculum amount and shaking speed.According to the results of single factor experiment,the optimal degradation conditions were obtained by response surface analysis.Results showed that,17 strains of enrofloxacin degrading bacteria were obtained in the initial screening,and 3 strains of enrofloxacin degrading bacteria were found in the further re-screening.BSFL-1 and BSFL-3 were identified as Enterococcus faecalis and BSFL-2 as Proteus mirabilis.The strain with the highest degradation rate was BSFL-3.By response surface analysis,the optimal degradation conditions were as follows:Temperature 33.6℃,initial pH5.8,inoculation amount 4%,shaking speed 155 r/min.Under these conditions,the degradation rate of enrofloxacin was 77.83%±0.53%.The strain with optimized degradation conditions has high degradation rate,which broadens the research field of biological degradation of enrofloxacin,and provides help for the application research of using bacterial degradation rate of enrofloxacin.