Abstract：
Pseudoalteromonas piscicida 2515, isolated from Litopenaeus vannamei culture water, is a potential marine probiotic with broad anti-Vibrio properties. However, genomic information on P. piscicida 2515 is scarce. In this study, the general genomic characteristics and probiotic properties of the P. piscicida 2515 strain were analysed. In addition, we determined the antibacterial mechanism of this bacterial strain by scanning electron microscopy (SEM). The results indicated that the whole-genome sequence of P. piscicida 2515 contained one chromosome and one plasmid, including a total length of 5,541,406 bp with a G + C content of 43.24%, and 4679 protein-coding genes were predicted. Various adhesion-related genes, amino acid and vitamin metabolism and biosynthesis genes, and stress-responsive genes were found with genome mining tools. The presence of genes encoding chitin, bromocyclic peptides, lantibiotics, and sactipeptides showed the strong antibacterial activity of the P. piscicida 2515 strain. Moreover, in coculture with Vibrio anguillarum, P. piscicida 2515 displayed vesicle/pilus-like structures located on its surface that possibly participated in its bactericidal activity, representing an antibacterial mechanism. Additionally, 16 haemolytic genes and 3 antibiotic resistance genes, including tetracycline, fluoroquinolone, and carbapenem were annotated, but virulence genes encoding enterotoxin FM (entFM), cereulide (ces), and cytotoxin K were not detected. Further tests should be conducted to confirm the safety characteristics of P. piscicida 2515, including long-term toxicology tests, ecotoxicological assessment, and antibiotic resistance transfer risk assessment. Our results here revealed a new understanding of the probiotic properties and antibacterial mechanism of P. piscicida 2515, in addition to theoretical information for its application in aquaculture.
摘要：
从凡纳滨对虾养殖水中分离出的piscicida假单胞菌2515，是一种具有广泛抗弧菌特性的潜在海洋益生菌。然而,Piscicida2515的基因组信息很少。在这项研究中,分析了毕赤酵母2515菌株的一般基因组特征和益生菌特性。此外,我们通过扫描电子显微镜（SEM）确定了该菌株的抗菌机制。结果表明，piscicida2515的全基因组序列含有一条染色体和一个质粒，包括5,541,406bp的总长度，G+C含量为43.24%，并预测了4679个蛋白质编码基因。各种粘附相关基因，氨基酸和维生素代谢和生物合成基因，用基因组挖掘工具发现了应激反应基因。编码几丁质的基因的存在，溴环肽，抗生素，并显示出较强的抗菌活性。此外，与anguillarum弧菌共培养，Piscicida2515显示位于其表面的囊泡/菌毛样结构，可能参与其杀菌活性，代表一种抗菌机制。此外,16个溶血基因和3个抗生素抗性基因，包括四环素,氟喹诺酮,碳青霉烯被注释，但是编码肠毒素FM（entFM）的毒力基因，cereulide(ces),未检测到细胞毒素K。应进行进一步的测试，以确认假单胞菌2515的安全特性，包括长期毒理学测试，生态毒理学评估，和抗生素耐药性转移风险评估。我们的结果在这里揭示了新的认识的益生菌特性和抗菌机制的P。piscicida2515，除了其在水产养殖中的应用的理论信息。
