筛选具有降解黄曲霉毒素B1(aflatoxin,AFB1)的菌株以用于黄曲霉毒素的生物降解。该实验采用以香豆素为唯一碳源的培养基进行初筛,采用ELISA试剂盒检测初筛菌株AFB1降解率的方法进行复筛,然后通过测定筛选菌株的生长曲线,对酸、胆碱、肠胃液的耐受性以及抑菌性能,对其抗逆性和抑菌性进行初步分析。通过初筛和复筛,筛选到1株具有较强的AFB1降解能力的菌株ZJ20,其降解率可达84.23％,经形态学观察、生理生化试验及16S rRNA序列测定,鉴定该菌株为枯草芽孢杆菌(Bacillus subtilis),将其命名为Bacillus subtilis ZJ20。菌株Bacillus subtilis ZJ20耐酸处理后存活率在69.11%以上,胆盐处理后存活率在68.12%以上,人工胃肠液中处理后存活率在62.39%以上,抑菌实验结果表明该菌对鼠伤寒沙门氏菌(Salmonella enterica subsp)ATCC14028、金黄色葡萄球菌(Staphylococcus aureaus)ATCC6538、大肠杆菌(Escherichia coli)CVCC1527均有良好抑菌活性。综上,筛选到1株可降解AFB1的枯草芽孢杆菌,该菌有较好的抗逆性和抑菌性。
To screen strains with the ability to degrade aflatoxin B1(AFB1), coumarin, which could degrade AFB1, was used as the only carbon source in medium for primary screening of strains. And the AFB1 degradation rate of each strain was detected by ELISA kit. Then the growth curve of the isolated strains was measured, and the tolerance to acid, choline and gastrointestinal fluid as well as the antibacterial performance were preliminarily analyzed. A strain ZJ20 with strong AFB1 degradation ability was screened by primary and secondary screening, the degradation rate of which reached 84.23%. The strain was identified as Bacillus subtilis by morphological observation, physiological and biochemical analysis and 16S rRNA sequence determination. The survival rate of B. subtilis ZJ20 was more than 69.11% after acid resistant treatment, more than 68.12% after bile salt treatment, and more than 62.39% after artificial intestinal fluid treatment. The results of bacteriostatic experiment showed that the strain had good bacteriostatic performance against Salmonella enterica subsp. enterica ATCC14028, Staphylococcus aureus ATCC6538 and Escherichia coli CVCC1527. An AFB1 degrading strain of B. subtilis was screened, which showed good resistance and antibacterial activity.
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