蚯蚓源贝莱斯芽孢杆菌的分离鉴定及安全性评价

Safety evaluation of Bacillus velezensis from earthworm

为了探究蚯蚓源菌株的安全性,从蚯蚓肠道分离1株菌命名为Y1,对该菌进行生化鉴定分析、16S rRNA测序、蛋白酶测定、溶血试验、药敏试验、抑菌试验和动物安全性试验评价该菌株的安全性。结果显示:该菌为贝莱斯芽孢杆菌,革兰染色呈阳性,能产生蛋白酶,无溶血反应;对环丙沙星、头孢羟氨苄、氟苯尼考、替米考星、庆大霉素、红霉素和复方新诺明高度敏感,对氨苄西林、羟氨苄青霉素及青霉素耐药;对大肠杆菌和金黄色葡萄球菌均有显著抑制效果(P<0.05);试验组小鼠脏器指数与对照组相比无显著性变化(P>0.05);通过Alpha指数与Beta指数多样性分析,在门水平上,试验组拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)丰度升高并占主导地位,在属水平上,试验组小鼠肠道中的特异性菌群Muribaculaceae、阿克曼菌属(Akkermansia)丰度升高;稀释性曲线显示试验组群落多样性较高;P coA分析表明试验组菌种相似性较大;细菌无移位情况出现。结果表明,贝莱斯芽孢杆菌Y1有一定的安全性,可以调节小鼠肠道菌群,提高微生物多样性,改善肠道健康。

In order to explore the safety of bacterial strain of earthworm, this project isolated a strain named Y1 from the intestinal tract of earthworm, and evaluated the safety of the strain by biochemical identification analysis, 16 S rRNA sequencing, protease determination, hemolysis test, drug sensitivity test, bacteriostasis test and animal safety test.The results showed that the bacterium was Bacillus velezensis and Gram staining was positive.It could produce protease and had no hemolysis reaction.It was highly sensitive to ciprofloxacin, cefalexin, flufenicol, timicol, gentamicin, erythromycin and cotrimoxazole, was resistant to ampicillin, ampicillin and penicillin.It had significant inhibitory effect on Escherichia coli and Staphylococcus aureus(P<0.05).There was no significant change in organ index of experimental group compared with control group(P>0.05).According to the diversity analysis of Alpha index and Beta index, the abundance of Bacteroidetes and Firmicutes in the experimental group increased and dominated at the phylum level, and at the genus level.The abundance of Muribaculaceae and Akkermansia in the intestinal tract of experimental group was increased.The dilution curve showed that the diversity of the experimental group was higher.P coA analysis showed that the strains in test group were more similar.No bacterial translocation occurred.In conclusion, Bacillus velezensis Y1 is safe and can regulate the intestinal flora of mice, improve microbial diversity and improve intestinal health.