Three bacterial strains, W99^T, S113^T, and S268^T, were isolated from marine algae and subjected to polyphasic taxonomic characterization. Phylogenetic and phylogenomic analyses placed W99^T within the genus Shimia, whereas S113^T and S268^T formed two distinct genus-level lineages within the family Roseobacteraceae. The three isolates were Gram-stain-negative, non-motile, and obligately aerobic, with optimum growth at 25, 25, and 30°C, respectively, and at 2.0% (w/v) NaCl. Ubiquinone-10 was the sole respiratory quinone in all three strains. The major fatty acids were 11-methyl C_18:1 ω7c and summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c) in strain W99^T; C_16:0 and summed feature 8 in strain S113^T; and 11-methyl C_18:1 ω7c, cyclo-C_19:0 ω8c, and summed feature 8 in strain S268^T. The major polar lipids were phosphatidylglycerol and phosphatidylcholine, with diphosphatidylglycerol additionally detected in strain S268^T. Polyphasic taxonomic analyses demonstrated that strain W99^T represents a novel species of the genus Shimia, for which the name Shimia rhodophyticola sp. nov. is proposed (W99^T = KACC 24154^T = JCM 38196^T), whereas strains S113^T and S268^T represent two novel genera and species, Neomarinovum algicola gen. nov., sp. nov. (S113^T = KACC 23417^T = JCM 38210^T) and Phycorhabdus gracilariae gen. nov., sp. nov. (S268^T = KACC 24156^T = JCM 38211^T), respectively. In addition, comprehensive phylogenomic and genome-based relatedness analyses support the taxonomic revision of nineteen taxa within the family Roseobacteraceae, providing a revised genome-based taxonomic framework that better reflects the evolutionary relationships within the family.

A Gram-stain-negative, aerobic, non-motile, rod-shaped, and orange-pigmented bacterium, designated CJ426^T, was isolated from ginseng soil in Anseong, Korea. Strain CJ426^T grew optimally on Reasoner’s 2A agar at 30°C and pH 7.0 in the absence of NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain CJ426^T belonged to the family Chitinophagaceae and had the highest sequence similarity with Niabella hibiscisoli KACC 18857^T (98.7%). The 16S rRNA gene sequence similarities with other members of the genus Niabella ranged from 92.3% to 98.1%. Phylogenomic analyses and overall genomic relatedness indices, including average nucleotide identity, average amino acid identity, and the percentage of conserved proteins values, supported the classification of strain CJ426^T as a representative of a novel genus within the family Chitinophagaceae. Furthermore, genome-based analyses suggested that five members of the genus Niabella, including N. aquatica, N. defluvii, N. ginsengisoli, N. hibiscisoli, and, N. yanshanensis, should be separated from other Niabella species and be assigned as a novel genus. The major isoprenoid quinone of strain CJ426^T was menaquinone-7 (MK-7). The predominant polar lipids were phosphatidylethanolamine and six unidentified aminolipids. The major fatty acids were iso-C_15:0, iso-C_15:1 G, and iso-C_17:0 3-OH. The genome of strain CJ426^T was 6.3 Mbp in size, consisting of three contigs, with a G + C content of 41.9%. Based on a polyphasic taxonomic approach, strain CJ426^T represents a novel genus and species within the family Chitinophagaceae, for which the name Paraniabella aurantiaca gen. nov., sp. nov. is proposed. The type strain is CJ426^T (= KACC 23908^T = JCM 37728^T).

Two novel, Gram-stain-negative, anaerobic, and non-motile bacterial strains, designated KFT8^T and CG01^T, were isolated from the feces of healthy individuals without diagnosed diseases and characterized using a polyphasic approach. Phylogenetic analysis revealed that both strains belong to the genus Bacteroides, with < 99.0% similarity in their 16S rRNA gene sequences to B. facilis NSJ-77^T and B. nordii JCM 12987^T. Within the genus Bacteroides, strain KFT8^T exhibited the highest Orthologous Average Nucleotide Identity value of 94.7% and a digital DNA-DNA hybridization value of 63.7% with B. ovatus ATCC 8483^T, whereas strain CG01^T showed the highest values of 95.3% and 63.3%, respectively, with B. nordii JCM 12987^T. The values between the two novel strains were 74.8% and 21.4%, respectively, which are below the species delineation thresholds, supporting their classification as novel species. The major fatty acid of strain KFT8^T was C_18:1 ω9c, whereas strain CG01^T predominantly contained summed feature 11 (comprising iso-C_17:0 3OH and/or C_18:2 DMA). The only respiratory quinone was MK-11, the major polar lipid was phosphatidylethanolamine. Both strains produced succinic acid and acetic acid as common metabolic end-products of fermentation, while lactic acid and formic acid were detected individually in each strain. Based on polyphasic characterization, strains KFT8^T (= KCTC 15614^T = JCM 36011^T) and CG01^T (= KCTC 15613^T = JCM 36010^T) represent two novel species within the genus Bacteroides, for which the names Bacteroides celer sp. nov. and Bacteroides mucinivorans sp. nov. are proposed, respectively. Additionally, genome-based analyses and phenotypic comparisons revealed that B. koreensis and B. kribbi represent the same strain, showing genomic relatedness to B. ovatus that exceeds the threshold for species delineation. Consequently, we propose the reclassification of B. koreensis Shin et al. 2017 and B. kribbi Shin et al. 2017 as later heterotypic synonyms of B. ovatus Eggerth and Gagnon 1933 (Approved Lists 1980).