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Abstract：
The present study involves the precise identification and safety evaluation of Enterococcus casseliflavus KB1733, previously identified using 16S rRNA analysis, through whole-genome sequencing, phenotypic analysis, and preclinical toxicity studies. Analyses based on the genome sequencing data confirm the identity of KB1733 as E. casseliflavus and show that the genes related to vancomycin resistance are only present on the chromosome, while no virulence factor genes are present on the chromosome or plasmid. Phenotypic analyses of antibiotic resistance and hemolytic activity also indicated no safety concerns. A bacterial reverse mutation test showed there was no increase in revertant colonies of heat-killed KB1733. An acute toxicity test employing heat-killed KB1733 at a dose of 2000 mg/kg body weight in rats resulted in no deaths and no weight gain or other abnormalities in the general condition of the animals, with renal depression foci and renal cysts only occurring at the same frequency as in the control. Taking the background data into consideration, the effects on the kidneys observed in the current study were not caused by KB1733. Our findings suggest that KB1733 is non-pathogenic to humans/animals, although further studies involving repeated oral toxicity tests and/or clinical tests are required.
摘要：
本研究涉及精确鉴定和安全性评估的肠球菌卡氏黄菌KB1733，以前使用16SrRNA分析鉴定，通过全基因组测序，表型分析，和临床前毒性研究。基于基因组测序数据的分析证实了KB1733是E.casseliflavus，并表明与万古霉素抗性相关的基因仅存在于染色体上，而染色体或质粒上不存在毒力因子基因。抗生素耐药性和溶血活性的表型分析也表明没有安全问题。细菌回复突变测试表明，热灭活的KB1733的回复菌落没有增加。在大鼠中以2000mg/kg体重的剂量使用热杀死的KB1733进行的急性毒性试验没有导致动物的死亡和体重增加或其他一般状况异常，肾衰灶和肾囊肿仅发生在与对照组相同的频率。考虑到背景数据，本研究中观察到的对肾脏的影响并非由KB1733引起.我们的研究结果表明，KB1733对人类/动物是非致病性的，尽管需要进行涉及重复口服毒性试验和/或临床试验的进一步研究。
