Complete genome sequencing of exopolysaccharide-producing <i>Lactobacillus plantarum</i> K25 provides genetic evidence for the probiotic functionality and cold endurance capacity of the strain

<i>Lactobacillus plantarum</i> (<i>L. plantarum</i>) K25 is a probiotic strain isolated from Tibetan kefir. Previous studies showed that this exopolysaccharide (EPS)-producing strain was antimicrobial active and cold tolerant. These functional traits were evidenced by complete genome sequencing of strain K25 with a circular 3,175,846-bp chromosome and six circular plasmids, encoding 3365 CDSs, 16 rRNA genes and 70 tRNA genes. Genomic analysis of <i>L. plantarum</i> K25 illustrates that this strain contains the previous reported mechanisms of probiotic functionality and cold tolerance, involving plantaricins, lysozyme, bile salt hydrolase, chaperone proteins, osmoprotectant, oxidoreductase, EPSs and terpenes. Interestingly, strain K25 harbors more genes that function in defense mechanisms, and lipid transport and metabolism, in comparison with other <i>L. plantarum</i> strains reported. The present study demonstrates the comprehensive analysis of genes related to probiotic functionalities of an EPS-producing <i>L. plantarum</i> strain based on whole genome sequencing. Ubiquitous and unique functional genes are the reason why an EPS-producing <i>L. plantarum</i> K25 strain has probiotic functionalities and stresses tolerances based on whole genome sequencing.

植物乳杆菌（Lactobacillus plantarum，简称L. plantarum）K25是一株从西藏开菲尔中分离得到的益生菌菌株。既往研究表明，这株产胞外多糖（exopolysaccharide，EPS）的菌株兼具抗菌活性与耐冷特性。上述功能特性经K25菌株的全基因组测序得以证实：其基因组包含一条长度为3175846 bp的环状染色体与6个环状质粒，共编码3365个编码序列（coding sequence, CDS）、16个核糖体RNA（rRNA）基因以及70个转运RNA（tRNA）基因。对植物乳杆菌K25的基因组分析显示，该菌株携带已报道的益生菌功能与耐冷相关机制，涵盖植物乳杆菌素、溶菌酶、胆汁盐水解酶、分子伴侣蛋白、渗透保护剂、氧化还原酶、胞外多糖与萜类化合物。值得注意的是，与已发表的其他植物乳杆菌菌株相比，K25菌株在防御机制、脂质转运与代谢通路中拥有更多的功能基因。本研究基于全基因组测序技术，对一株产胞外多糖的植物乳杆菌菌株的益生菌功能相关基因开展了全面分析。基于全基因组测序结果，普遍存在且独具特色的功能基因，正是产胞外多糖的植物乳杆菌K25菌株具备益生菌功能与胁迫耐受性的内在原因。