| Abstract |
Three marine bacteria in Bacteroidales, designated FJH62T, FJH65T and FJH54T, were isolated from mangrove sediments at the Zhangjiang River estuary in Fujian, China. The cells were Gram-stain-negative, facultatively anaerobic, non-motile and straight to curved rod-shaped. Comparative analysis of the 16S rRNA gene showed that strains FJH62T and FJH65T shared 88.9-89.0 % identity with Saccharicrinis carchari SS12T, while strain FJH54T had the maximum similarity of 88.8 % to Carboxylicivirga taeanensis MEBiC 08093T. Whole-genome relatedness indices further distinguished these isolates from other relatives, falling below the established thresholds, with strains FJH62T, FJH65T, and FJH54T identified as three distinct novel species. Phylogenetic analysis based on both 16S rRNA gene and whole genome sequences indicated that these three novel strains form a monophyletic branch within the order Bacteroidales. These isolates were distinguished from their closest relatives by the presence of MK-10 as the major respiratory quinone and phosphatidylethanolamine, aminolipids, and phospholipids as the predominant polar lipids. The major cellular fatty acids and DNA G + C content were identified as iso-C15:0 and anteiso-C15:0 and 38.5-39.9 %, respectively. Genomic analysis and experimental validation confirmed nitrogen-fixing and Fe(III)-reducing abilities of these three strains. Based on polyphasic characterizations, these three strains represent three novel species of a novel genus, for which the names Quyinboa mangrovi gen. nov., sp. nov. (FJH62T = KCTC 102258T = MCCC 1H01534T), Quyinboa ferrireducens sp. nov. (FJH65T = KCTC 102259T = MCCC 1H01536T), and Quyinboa sediminis sp. nov. (FJH54T = KCTC 102257T = MCCC 1H01535T) are proposed. Furthermore, a novel family, Quyinboaceae fam. nov., is proposed within the order Bacteroidales.
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