title: Safety Evaluation of a Novel Strain ofBacteroides fragilis.
abstract: Commensal non-toxigenicBacteroides fragilisconfers powerful health benefits to the host, and has recently been identified as a promising probiotic candidate. We previously isolatedB. fragilisstrain ZY-312 and identified it as a novel strain based on 16S rRNA sequencing and morphological analyses. We also determined that ZY-312 displayed desirable probiotic properties, including tolerance to simulated digestive fluid, adherence, andin vitrosafety. In this study, we aim to investigate whether ZY-312 meets the safety criteria required for probiotic bacteria through comprehensive and systematic evaluation. Consequently, the fatty acid profile, metabolite production, and biochemical activity of strain ZY-312 were found to closely resemble descriptions ofB. fragilisin Bergey's manual. Taxonomic identification of strain ZY-312 based on whole genome sequencing indicated that ZY-312 and ATCC 25285 showed 99.99% similarity. The 33 putative virulence-associated factors identified in ZY-312 mainly encoded structural proteins and proteins with physiological activity, while the lack ofbftindicated that ZY-312 was non-toxigenic.In vivosafety was proven in both normal and immune-deficient mice. The 11 identified antibiotic resistance genes were located on the chromosome rather than on a plasmid, ruling out the risk of plasmid-mediated transfer of antibiotic resistance.In vitro, ZY-312 showed resistance to cefepime, kanamycin, and streptomycin. Finally, and notably, ZY-312 exhibited high genetic stability after 100 passagesin vitro. This study supplements the foundation work on the safety evaluation of ZY-312, and contributes to the development of the first probiotic representative from the dominant Bacteroidetes phylum.
authors.affiliation: Institute of Genetic Engineering, Jinan University,Guangzhou, China; Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology, Nanfang Hospital, Southern Medical University,Guangzhou, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology, Nanfang Hospital, Southern Medical University,Guangzhou, China; State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology,Beijing, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Deng
authors.affiliation: Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology, Nanfang Hospital, Southern Medical University,Guangzhou, China; State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology,Beijing, China.
authors.forename: Zhengchao
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Yafang
authors.initials: Y
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Han
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Zongmin
authors.initials: Z
authors.lastname: Du
authors.affiliation: Guangzhou ZhiYi biotechnology Co. Ltd., Guangzhou, China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Ruifu
authors.initials: R
authors.lastname: Yang
authors.affiliation: Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Bai
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
authors.forename: Yujing
authors.initials: Y
authors.lastname: Bi
authors.affiliation: Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: Fachao
authors.initials: F
authors.lastname: Zhi
keywords: Bacteroides fragilis; genetic stability; probiotic; safety evaluation; whole genome sequencing