Yang Lei-Lei, Xin Yu-Hua, Liu Qing
China General Microbiological Culture Collection Center, Institute of Microbiology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing, 100101, People's Republic of China.
Beijing Key Laboratory of Genetic Element Biosourcing & Intelligent Design for Biomanufacturing, Beijing, 100101, China.
BMC Microbiol. 2025 May 28;25(1):336. doi: 10.1186/s12866-025-04067-4.
Six novel cold-adapted bacteria, LB3P122, LT1R49, ZT3R17, ZT3R25, XS2P12, and GB2R13, were isolated from glaciers on the Tibetan Plateau. This study aimed to characterize their taxonomic status and elucidate their molecular adaptations to cold environments using a polyphasic approach.
All strains were Gram-stain-negative, rod-shaped, and psychrophilic, growing at 0 °C with an optimum at 14-20 °C and at pH values of 6.0-8.0 (optimum pH 7.0). Analysis of the 16S rRNA gene sequences placed their taxonomic positions within the genus Flavobacterium, with similarities ranging from 97.2 to 98.4% to species with validly published names. Phylogenetic analysis of the 16S rRNA gene sequences revealed that the six strains formed distinct clades with Flavobacterium gawalongense GSP16. Phylogenomic analysis showed that these strains clustered with Flavobacterium gawalongense GSP16 and exhibited a close relationship with Flavobacterium urumqiense CGMCC 1.9230 and Flavobacterium xinjiangense CGMCC 1.2749. Average nucleotide identity (ANI) values ranging from 82.5 to 93.6% and digital DNA-DNA hybridization (dDDH) values ranging from 26.1 to 51.5% between these strains and their closest relatives were well below the bacterial species delineation thresholds (95-96% ANI, 70% dDDH). The predominant fatty acids were iso-C and summed feature 3 (C ω7c and/or C ω6c). Genomic analysis identified genes associated with cryoprotection, oxidative stress response, cold-shock response, and osmoprotection in these strains, underscoring their adaptations to glacial environments.
Based on polyphasic taxonomic evidence, the strains represent six novel species within the genus Flavobacterium, with the proposed names Flavobacterium algoriphilum sp. nov. (LB3P122 = CGMCC 1.11443 = NBRC 114820), Flavobacterium arabinosi sp. nov. (LT1R49 = CGMCC 1.11617 = NBRC 114822), Flavobacterium cryoconiti sp. nov. (ZT3R17 = CGMCC 1.11707 = NBRC 114824), Flavobacterium galactosi sp. nov. (ZT3R25 = CGMCC 1.11711 = NBRC 114825), Flavobacterium melibiosi sp. nov. (XS2P12 = CGMCC 1.23198 = NBRC 114826), and Flavobacterium algoris sp. nov. (GB2R13 = CGMCC 1.24741 = NBRC 114830). These findings enhance our understanding of Flavobacterium diversity and cold adaptation in cryospheric ecosystems.
从青藏高原的冰川中分离出六种新型嗜冷细菌，LB3P122、LT1R49、ZT3R17、ZT3R25、XS2P12和GB2R13。本研究旨在通过多相分类方法确定它们的分类地位，并阐明它们对寒冷环境的分子适应性。
所有菌株均为革兰氏阴性、杆状且嗜冷，在0°C下生长，最适生长温度为14 - 20°C，pH值为6.0 - 8.0（最适pH 7.0）。对16S rRNA基因序列的分析确定它们在黄杆菌属中的分类地位，与有效发表名称的物种相似性范围为97.2%至98.4%。16S rRNA基因序列的系统发育分析表明，这六种菌株与高海拔黄杆菌GSP16形成了不同的进化分支。全基因组分析表明，这些菌株与高海拔黄杆菌GSP16聚类，并与乌鲁木齐黄杆菌CGMCC 1.9230和新疆黄杆菌CGMCC 1.2749表现出密切关系。这些菌株与其最接近的亲缘种之间的平均核苷酸同一性（ANI）值在82.5%至93.6%之间，数字DNA - DNA杂交（dDDH）值在26.1%至51.5%之间，远低于细菌物种划分阈值（95 - 96% ANI，70% dDDH）。主要脂肪酸为异C和总和特征3（C ω7c和/或C ω6c）。基因组分析在这些菌株中鉴定出与低温保护、氧化应激反应、冷休克反应和渗透保护相关的基因，突出了它们对冰川环境的适应性。
基于多相分类证据，这些菌株代表黄杆菌属中的六个新物种，提议的名称为嗜冷黄杆菌新种（LB3P122 = CGMCC 1.11443 = NBRC 114820）、阿拉伯糖黄杆菌新种（LT1R49 = CGMCC 1.11617 = NBRC 114822）、冰粒黄杆菌新种（ZT3R17 = CGMCC 1.11707 = NBRC 114824）、半乳糖黄杆菌新种（ZT3R25 = CGMCC 1.11711 = NBRC 114825）、蜜二糖黄杆菌新种（XS2P12 = CGMCC 1.23198 = NBRC 114826）和嗜冷黄杆菌新种（GB2R13 = CGMCC 1.24741 = NBRC 114830）。这些发现增进了我们对冰冻圈生态系统中黄杆菌多样性和冷适应性的理解。
