Wei Cong, Luo Kai, Wang Mingyang, Li Yongmei, Pan Miaojun, Xie Yumeng, Qin Guangcai, Liu Yijun, Li Li, Liu Qingbing, Tian Xiangli
The Key Laboratory of Mariculture, Ocean University of China, Ministry of Education, Qingdao, China.
Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
Front Microbiol. 2022 Mar 24;13:854131. doi: 10.3389/fmicb.2022.854131. eCollection 2022.
In recent years the safety of probiotics has received increasing attention due to the possible transfer and spread of virulence factors (VFs) and antibiotic resistance genes (ARGs) among microorganisms. The safety of a strain of named W2 was evaluated in phenotype and genotype in the present study. Its probiotic properties were also evaluated both and , including adherence properties, antibacterial properties and beneficial effects on the growth and immunity of Pacific white shrimp, . Hemolysis tests, antibiotic resistance tests and whole genome sequence analysis showed that W2 had no significant virulence effects and did not carry high virulence factors. W2 was found to be sensitive to chloramphenicol, clindamycin, gentamicin, kanamycin and tetracycline, and to be resistant to ampicillin and erythromycin. Most ARGs have no transfer risk and a few have transfer risk but no significant enrichment in human-associated environments. The autoaggregation of W2 was 82.6% and the hydrophobicity was 81.0%. Coaggregation rate with (24.9%) was significantly higher than 's autoaggregation rate (17.8%). This suggested that W2 had adhesion potential to mucosal/intestinal surfaces and was able to attenuate the adherence of . In addition, several adhesion-related protein genes, including 1 S-layer protein, 1 collagen-binding protein and 9 mucus-binding proteins were identified in the W2 genome. W2 had efficiently antagonistic activity against 7 aquatic pathogenic strains. Antagonistic components analysis indicated that active antibacterial substances might be organic acids. W2 can significantly promote the growth of shrimp when supplemented with 1 × 10 cfu/kg live cells. Levels of 7 serological immune indicators and expression levels of 12 hepatopancreatic immune-related genes were up-regulated, and the mortality of shrimp exposed to was significantly reduced. Based on the above, W2 can be applied safely as a potential probiotic to enhance the growth performance, immunity capacity and disease resistance of .
近年来，由于毒力因子（VFs）和抗生素抗性基因（ARGs）在微生物之间可能的转移和传播，益生菌的安全性受到了越来越多的关注。本研究对一株名为W2的菌株进行了表型和基因型安全性评估。还在体内和体外评估了其益生菌特性，包括黏附特性、抗菌特性以及对凡纳滨对虾生长和免疫的有益作用。溶血试验、抗生素抗性试验和全基因组序列分析表明，W2没有明显的毒力作用，也不携带高毒力因子。发现W2对氯霉素、克林霉素、庆大霉素、卡那霉素和四环素敏感，对氨苄青霉素和红霉素耐药。大多数ARGs没有转移风险，少数有转移风险，但在人类相关环境中没有显著富集。W2的自凝率为82.6%，疏水性为81.0%。与哈维氏弧菌的共凝率（24.9%）显著高于哈维氏弧菌的自凝率（17.8%）。这表明W2对黏膜/肠道表面具有黏附潜力，并能够减弱哈维氏弧菌的黏附。此外，在W2基因组中鉴定出了几个与黏附相关的蛋白质基因，包括1个S层蛋白、1个胶原结合蛋白和9个黏液结合蛋白。W2对7株水产致病菌株具有高效拮抗活性。拮抗成分分析表明，活性抗菌物质可能是有机酸。当添加1×10 cfu/kg活细胞时，W2可以显著促进对虾生长。7种血清免疫指标水平和12个肝胰腺免疫相关基因的表达水平上调，暴露于哈维氏弧菌的对虾死亡率显著降低。基于以上结果，W2作为一种潜在的益生菌可以安全应用，以提高凡纳滨对虾的生长性能、免疫能力和抗病能力。
