Flagellatimonas centrodinii gen. nov., sp. nov., a novel member of the family Nevskiaceae isolated from toxin-producing dinoflagellate Centrodinium punctatum

Discovery of two novel Flavobacterium species with potential for complex polysaccharide degradation

Polysaccharides are recognized for their extensive biological functions, holding significant promise for applications in both medicine and food industries. However, their utilization is frequently constrained by challenges such as high molecular weights and indistinct sugar chain structures. Recently, two novel bacterial strains, N6T and J3T, were isolated from the Nakdong River in Korea. These strains, which belong to the phylum Bacteroidota, are Gram-stain-negative, non-motile, aerobic, rod-shaped bacteria and have shown polysaccharide-degrading capabilities. Through comprehensive analyses, including 16S rRNA gene sequencing, whole-genome sequencing, and detailed morphological, physiological, and chemotaxonomic characterizations, these strains have been identified as new species within the genus Flavobacterium. KEGG pathway analysis further confirmed their robust capabilities for carbohydrate utilization. Additional investigations using the dbCAN and dbCAN-PUL databases identified the presence of carbohydrate-hydrolyzing enzymes (CAZymes) and polysaccharide utilization loci (PULs) within these strains, suggesting their potential to degrade various polysaccharides. Subsequent in vitro growth experiments demonstrated that strains N6T and J3T can degrade chitin, β-glucan, κ-carrageenan, and cellulose. Given their diverse polysaccharide degradation abilities, these strains are formally proposed to be named Flavobacterium polysaccharolyticum sp. nov. and Flavobacterium aureirubrum sp. nov. The type strains are designated as N6T (= KCTC 102173T = GDMCC 1.4609T) and J3T (= KCTC 102172T = GDMCC 1.4608T), respectively.

Emticicia fluvialis sp. nov., a potential hormone-degrading bacterium isolated from Nakdong River, Republic of Korea

A novel species of the genus Emticicia, designated BHSR1T, was isolated from a water sample that was collected from the Nakdong River, Republic of Korea, and its taxonomic affiliation was studied using a polyphasic approach. This bacterium was Gram-stain-negative, non-motile, aerobic, curved, rod-shaped, and oxidase- and catalase-negative. The bacterium grew optimally at 37 °C, pH 7.5 and 0% (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain BHSR1T should be affiliated with the genus Emticicia, with a high similarity to Emticicia fontis KCTC 52248T (98.10%). Phylogenomic analysis also suggested that the strain represents a novel species in the genus Emticicia. The genomic G + C content was 41.9%. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization between strain BHSR1T and its closely related relatives in the genus Emticicia were in ranges of 71.1-75.8%, 69.4-77.5% and 18.6-19.9%, respectively. The gene cluster within BHSR1T contained genes encoding enzymes that could be involved in hormone degradation. The major cellular fatty acids (> 10%) were summed feature 3 (comprising C16:1ω6c and/or C16:1ω7c) and iso-C15:0. With regards to the polar lipid profile, phosphatidylethanolamine (PE), two unidentified aminolipids and three unidentified lipids were identified as the major compounds. The major respiratory quinone was menaquinone (MK)-7. Based on its phylogenetic, phenotypic, chemotaxonomic, and genomic features, strain BHSR1T should be considered a novel species in the genus Emticicia of the family Spirosomaceae, for which the name Emticicia fluvialis sp. nov. is proposed. The type strain was considered BHSR1T (= KCTC 92622T = GDMCC 1.3740T).

Dasania phycosphaerae sp. nov., isolated from phytoplankton sample from the south coast of the Republic of Korea

A novel bacterial strain, designated as GY-18T, was isolated from particulate material sampled from the Korean south coast. The bacterium was Gram-stain-negative, aerobic and rod-shaped. Oxidase and catalase were positive. Optimal growth was observed at 30 °C, pH 7.0, in the presence of 1 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene and whole-genome sequences suggested that strain GY-18T was a member of the genus Dasania , but represented a separate lineage. The 16S rRNA gene sequence of strain GY-18T showed high similarities to Dasania marina KCTC 12566T (98.4 %), Halioglobus japonicus KCTC 23429T (92.2 %), Marimicrobium arenosum KCTC 42300T (92.4 %) and Seongchinamella unica KCTC 62383T (92.2 %), respectively. The genome length of strain GY-18T was 3 808 450 bp with a DNA G+C content of 47.8 mol %. The major cellular fatty acids of strain GY-18T were summed feature 3 (comprising C16 : 1  ω7c and/or C16 : 1  ω6c), C16 : 0 and C10 : 0 3-OH (>10 %). Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phospholipids were shown to be the major polar lipids. The predominant isoprenoid quinone was Q-8. Based on phylogenetic, phenotypic, chemotaxonomic and genomic features, we propose that strain GY-18T represents a novel species in the genus Dasania of the family Spongiibacteraceae , with the proposed name Dasania phycosphaerae sp. nov. The type strain is GY-18T (=KCTC 92290T=GDMCC 1.3586T).

Gymnodinialimonas ceratoperidinii gen. nov., sp. nov., isolated from rare marine dinoflagellate Ceratoperidinium margalefii

A bacterial strain, designated J12C1-MA-4^T, was isolated from liquid culture of the dinoflagellate Ceratoperidinium margalefii. The bacterium was Gram-negative, aerobic, and rod-shaped. Oxidase and catalase were positive. Optimal growth was observed at 30 °C, pH 7.0, in the presence of 1% (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene and a 92 core gene set suggested that the strain J12C1-MA-4^T belongs to the family Rhodobacteraceae in the class Alphaproteobacteria and represents a taxon separated from other genera. 16S rRNA gene sequence of the strain J12C1-MA-4^T showed high similarities to Loktanella ponticola KCTC 42133^T (95.7%), Pseudooctadecabacter jejudonensis KCTC 32525^T (95.5%) and Jannaschia helgolandensis KCTC 12191^T (95.3%). The genome length of strain J12C1-MA-4^T was 3,621,968 bp with a DNA G + C content of 64.48 mol%. The major cellular fatty acids of strain J12C1-MA-4^T were summed feature 8 (comprising C_18:1ω7c and/or C_18:1ω6c) (> 10%). Phosphatidylglycerol (PG), phosphatidylcholine (PC), phospholipids (PL), lipids 1 (L1) and aminolipid (AL) were shown to be the major polar lipids. The sole predominant isoprenoid quinone was Q-10. Based on phylogenetic, phenotypic, chemotaxonomic and genomic features, we propose that strain J12C1-MA-4^T represent a novel species in the novel genus of the family Rhodobacteraceae, with the proposed name Gymnodinialimonas ceratoperidinii gen. nov., sp. nov.. The type strain is J12C1-MA-4^T (=KCTC 82770^T =GDMCC 1.2729^T).