产吲哚金黄杆菌YM5毒性相关基因及其急性经口毒性

Analysis of virulence-related genes and acute oral toxicity of Chryseobacterium indologenes YM5

产吲哚金黄杆菌(Chryseobacterium indologenes)YM5是本实验室分离所得的一株具有高效羽毛角蛋白降解能力的革兰氏阴性菌,具有潜在的工业应用价值,但部分产吲哚金黄杆菌的相关株系被报道可能为医院条件致病菌.本研究通过测定YM5全基因组序列,分析其基因组中毒性相关功能基因,结合小鼠急性经口毒性试验,来评价YM5的生物安全性.结果显示,YM5基因组内不含毒性相关基因.YM5菌液及其羽毛发酵液对小鼠半数致死量(LD50)大于20 g/kg BW,属实际无毒级;处理14 d后,小鼠血清中谷丙转氨酶(AST)、谷草转氨酶(ALT)、尿素(BUN)、肌酐(Cre)、血糖(GLU)、总胆固醇(TC)和甘油三酯(TG)与对照组均无显著性差异(P>0.05).本研究表明YM5菌液及其羽毛发酵液对哺乳动物安全无毒副作用,可应用于工业生产.

Chryseobacterium indologenes YM5 is a Gram-negative strain isolated by our laboratory, which can degrade feather keratin, and therefore, has potential for industrial application. However, some strains of C. indologenes have been reported as opportunistic pathogens in hospitals. Therefore, its whole genome was sequenced and its virulence-related genes were analyzed, and a mouse acute oral toxicity test was conducted to assess the safety of strain YM5. The results suggested that no virulence-related genes are present in the genome of the YM5 strain. The results of the acute oral toxicity test indicated that the YM5 strain and its keratin fermentation broth were nontoxic, because their median lethal doses （LD50） were more than 20 g/kg BW. The serum levels of aspartate aminotransferase, alanine aminotransferase, urea nitrogen, creatinine, glucose, total cholesterol, and triglyceride in mice treated with the YM5 strain and its feather fermentation broth were measured, and there were no remarkable differences （P 〉 0.05） compared those of the control group 14 days after treatment. Therefore, these results suggest that the YM5 strain and its keratin fermentation broth are safe in mammals and could be used in industrial applications.