比较基因组学揭示清酒广布乳杆菌在不同生态位中的适应性进化OA

Latilactobacillus sakei,a versatile lactic acid bacterium,is widely distributed in various ecological niches,including fer-mented foods,plants and animals,and holds significant industrial importance.This study conducted comparative genomic analyses of sev-en newly sequenced L.sakei isolates and 98 genome sequences downloaded from the National Center for Biotechnology Information(NCBI)database.The average genome size of these strains was(1.98±0.07)Mb,with an average GC content of(41.05±0.12)％and the number of coding sequences was 1 961±80.Analysis revealed that L.sakei possesses a closed pangenome,indicative of considerable adaptability and ecological plasticity.105 L.sakei strains were divided into three distinct clades:Clade Ⅰ,Clade Ⅱ,and Clade Ⅲ.Strains from fermented foods(46.94％)tended to cluster in Clade Ⅱ,while strains from plants(35.19％)showed a clustering trend in Clade Ⅲ.Plant isolates exhibited significantly higher genes numbers of plant-specific glycosyl hydrolases(e.g.GH32 and GH91;P＜0.05),conferring superior adaptability to high-starch and sucrose-rich environments.Additionally,CRISPR/Cas systems,predominantly of type ⅡA,were identified in 31 of the 105 strains,occurring with a higher frequency in isolates from animal and food fermentation sources(84％)than in those from plants(3％),dairy(3％),and other environments(10％),highlighting niche-specific adaptive traits.This study provides important findings on the genomic plasticity and adaptive strategies of L.sakei,offering data support for the re-search on its deeper habitat adaptation evolution.