Flavobacterium maris sp. nov. isolated from shallow sediments of the Sea of Japan

Paenimyroides aestuarii gen. nov. sp. nov., a novel bacterium isolated from sediment in the Pearl River Estuary and reclassification of five Flavobacterium and four Myroides species

An aerobic, Gram-negative, non-motile, yellow-to-orange pigmented and round bacterium, designated strain SCSIO 72103T, was isolated from sediment collected in the Pearl River Estuary, Guangdong Province, PR China and subjected to a polyphasic taxonomic study. Growth occurred at 20-37 °C (optimum, 28 °C), pH 6-8 (optimum, pH 7) and with 1-5.5% NaCl (optimum, 1-3 %). Comparative 16S rRNA gene analysis indicated that strain SCSIO 72103T had the highest similarities to Flavobacterium baculatum SNL9T (94.7 %) and Myroides aquimaris SW105T (94.2 %). Phylogenetic analysis based 16S rRNA gene sequences showed that strain SCSIO 72103T formed a single clade with M. aquimaris SW105T. Strain SCSIO 72103T contained iso-C15 : 0 as the major fatty acid and the predominant respiratory quinone was menaquinone MK-6. These characteristics are consistent with those of F. baculatum SNL9T and M. aquimaris SW105T. Phosphatidylethanolamine, most notably, unidentified aminolipid and unidentified aminophospholipid were major polar lipids. Strain SCSIO 72103T had a single circular chromosome of 2.96 Mb with a DNA G+C content of 35.1 mol%. The average nucleotide identity, average amino acid identity (AAI) and digital DNA-DNA hybridization values showed that the pairwise similarities between SCSIO 72103T and the type strains of F. baculatum SNL9T and M. aquimaris SW105T were 78.5-80.5 %, 79.0-81.4 % and 22.7-22.8 %, respectively. The AAI values between species in this clade and the type species of Flavobacterium and Myroides were below the 65 % threshold, indicating that these species belong to a novel genus. On the basis of phylogenetic, physiological and chemotaxonomic characteristics, strain SCSIO 72103T represents a new species of a novel genus, for which the name Paenimyroides aestuarii gen. nov. sp. nov. is proposed. The type strain is SCSIO 72103T (=KCTC 92043T=MCCC 1K06659T). It is also proposed that nine known species in the genera Flavobacterium and Myroides are reclassified as Paenimyroides species.

Interplay between the microalgae Micrasterias radians and its symbiont Dyadobacter sp. HH091

Based on previous research, related to detailed insight into mutualistic collaboration of microalga and its microbiome, we established an artificial plant-bacteria system of the microalga Micrasterias radians MZCH 672 and the bacterial isolate Dyadobacter sp. HH091. The bacteria, affiliated with the phylum Bacteroidota, strongly stimulated growth of the microalga when it was added to axenic algal cultures. For further advances, we studied the isolate HH091 and its interaction with the microalga M. radians using transcriptome and extensive genome analyses. The genome of HH091 contains predicted polysaccharide utilizing gene clusters co-working with the type IX secretion system (T9SS) and conceivably involved in the algae-bacteria liaison. Here, we focus on characterizing the mechanism of T9SS, implementing the attachment and invasion of microalga by Dyadobacter sp. HH091. Omics analysis exposed T9SS genes: gldK, gldL, gldM, gldN, sprA, sprE, sprF, sprT, porU and porV. Besides, gld genes not considered as the T9SS components but required for gliding motility and protein secretion (gldA, gldB, gldD, gldF, gldG, gldH, gldI, gldJ), were also identified at this analysis. A first model of T9SS apparatus of Dyadobacter was proposed in a course of this research. Using the combination of fluorescence labeling of Dyadobacter sp. HH091, we examined the bacterial colonisation and penetration into the cell wall of the algal host M. radians MZCH 672.

The fish pathogen Flavobacterium columnare represents four distinct species: Flavobacterium columnare, Flavobacterium covae sp. nov., Flavobacterium davisii sp. nov. and Flavobacterium oreochromis sp. nov., and emended description of Flavobacterium columnare

Flavobacterium columnare is the causative agent of columnaris disease in freshwater fish and four discrete genetic groups exist within the species, suggesting that the species designation requires revision. The present study determined the taxonomic status of the four genetic groups of F. columnare using polyphasic and phylogenomic approaches and included five representative isolates from each genetic group (including type strain ATCC 23463^T; genetic group 1). 16S rRNA gene sequence analysis revealed genetic group 2 isolate AL-02-36^T, genetic group 3 isolate 90-106^T, and genetic group 4 isolate Costa Rica 04-02-TN^T shared less than <98.8 % sequence identity to F. columnare ATCC 23463^T. Phylogenetic analyses of 16S rRNA and gyrB genes using different methodologies demonstrated the four genetic groups formed well-supported and distinct clades within the genus Flavobacterium. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (GGDC) values between F. columnare ATCC 23463^T, genetic group 2 isolate AL-02-36^T, genetic group 3 isolate 90-106^T, and genetic group 4 isolate Costa Rica 04-02-TN^T were less than 90.84% and 42.7%, respectively. Biochemical and physiological characteristics were similar among the four genetic groups; however, quantitative differences in fatty acid profiles were detected and MALDI-TOF analyses demonstrated numerous distinguishing peaks unique to each genetic group. Chemotaxonomic, MALDI-TOF characterization and ANI/GGDC calculations afforded differentiation between the genetic groups, indicating each group is a discrete species. Herein, the names F. covae sp. nov. (AL-02-36^T), F. davisii sp. nov. (90-106^T), and F. oreochromis sp. nov. (Costa Rica 04-02-TN^T) are proposed to represent genetic groups 2, 3, and 4, respectively.

Flavobacterium flabelliforme sp. nov. and Flavobacterium geliluteum sp. nov., Two Multidrug-Resistant Psychrotrophic Species Isolated From Antarctica

Despite unfavorable Antarctic conditions, such as cold temperatures, freeze-thaw cycles, high ultraviolet radiation, dryness and lack of nutrients, microorganisms were able to adapt and surprisingly thrive in this environment. In this study, eight cold-adapted Flavobacterium strains isolated from a remote Antarctic island, James Ross Island, were studied using a polyphasic taxonomic approach to determine their taxonomic position. Phylogenetic analyses based on the 16S rRNA gene and 92 core genes clearly showed that these strains formed two distinct phylogenetic clusters comprising three and five strains, with average nucleotide identities significantly below 90% between both proposed species as well as between their closest phylogenetic relatives. Phenotyping revealed a unique pattern of biochemical and physiological characteristics enabling differentiation from the closest phylogenetically related Flavobacterium spp. Chemotaxonomic analyses showed that type strains P4023^T and P7388^T were characterized by the major polyamine sym-homospermidine and a quinone system containing predominantly menaquinone MK-6. In the polar lipid profile phosphatidylethanolamine, an ornithine lipid and two unidentified lipids lacking a functional group were detected as major lipids. These characteristics along with fatty acid profiles confirmed that these species belong to the genus Flavobacterium. Thorough genomic analysis revealed the presence of numerous cold-inducible or cold-adaptation associated genes, such as cold-shock proteins, proteorhodopsin, carotenoid biosynthetic genes or oxidative-stress response genes. Genomes of type strains surprisingly harbored multiple prophages, with many of them predicted to be active. Genome-mining identified biosynthetic gene clusters in type strain genomes with a majority not matching any known clusters which supports further exploratory research possibilities involving these psychrotrophic bacteria. Antibiotic susceptibility testing revealed a pattern of multidrug-resistant phenotypes that were correlated with in silico antibiotic resistance prediction. Interestingly, while typical resistance finder tools failed to detect genes responsible for antibiotic resistance, genomic prediction confirmed a multidrug-resistant profile and suggested even broader resistance than tested. Results of this study confirmed and thoroughly characterized two novel psychrotrophic Flavobacterium species, for which the names Flavobacterium flabelliforme sp. nov. and Flavobacterium geliluteum sp. nov. are proposed.

Flavobacterium supellecticarium sp. nov., isolated from an abandoned construction timber

A bacterial strain CC-CTC003^T was isolated from a synthetic wooden board. Cells of strain CC-CTC003^T were Gram-stain-negative, rod-shaped, motile by gliding and formed yellow colonies. Optimal growth occurred at 25 °C, pH 7 and in the presence of 1 % NaCl. The phylogenetic analyses based on 16S rRNA genes revealed that strain CC-CTC003^T belonged to the genus Flavobacterium and was most closely related to Flavobacterium cerinum (95.3 % sequence identity), Flavobacterium maris (94.9 % sequence identity), Flavobacterium qiangtangense (94.8 %) and Flavobacterium subsaxonicum (94.7 %) and had less than 94.7 % sequence similarity to other members of the genus. Average nucleotide identity (ANI) values between strain CC-CTC003^T and the type strains of other closely related species were 70.1-74.1 %. The digital DNA-DNA hybridization (dDDH) with F. cerinum was 19.4 %. Strain CC-CTC003^T contained C_15 : 0, iso-C_15 : 0, iso-C_15 : 0 3-OH, iso-C_17 : 0 3-OH, summed feature 3 (C_16 : 1  ω6c / C_16 : 1  ω7c) and summed feature 9 (C_16 : 0 10-methyl / iso-C_17 : 1  ω9c) as the predominant fatty acids. The polar lipid profile consisted of phosphatidylethanolamine, four uncharacterized aminophospholipids, two aminolipids and one unidentified glycolipid. The major polyamine was sym-homospermidine and contained MK-6 as major isoprenoid quinone. The DNA G+C content of the genomic DNA was 39.2 mol%. On the basis of the phylogenetic inference and phenotypic data, strain CC-CTC003^T should be classified as a novel species, for which the name Flavobacterium supellecticarium sp. nov. is proposed. The type strain is CC-CTC003^T (=BCRC 81146^T=JCM 32838^T).

Flavobacterium chryseum sp. nov. and Flavobacterium psychroterrae sp. nov., novel environmental bacteria isolated from Antarctica

A group of rod-shaped, aerobic, Gram-stain-negative, gliding bacteria producing flexirubin-type pigment was isolated from environmental samples collected in Antarctica in 2009-2014. Phylogenetic analysis of the almost complete 16S rRNA gene sequences revealed two separated branches belonging to the genus Flavobacterium. Group I (n=8), represented by strain CCM 8826^T, shared the highest sequence similarity to Flavobacterium collinsii 983-08^T (98.8 %) and Flavobacterium saccharophilum DSM 1811^T (98.4 %), and group II (n=4) represented by strain CCM 8827^T shared the highest similarity to Flavobacterium aquidurense WB 1.1-56^T (99.6 %). High genetic homogeneity of both groups, separation from each other and from phylogenetically close Flavobacterium species was verified by the rep-PCR fingerprinting method. DNA-DNA hybridization confirmed low genomic relatedness between strain CCM 8826^T and F. collinsii 983-08^T and F. saccharophilum DSM 1811^T (18 and 28 %, respectively) and between strain CCM 8827^T and F. aquidurense WB 1.1-56^T (27 %). Chemotaxonomic analyses of strains CCM 8826^T and CCM 8827^T revealed the respiratory quinone to be MK-6, the major identified polar lipid was phosphatidylethanolamine and the predominant polyamine was sym-homospermidine. The common major fatty acids were C15 : 0 iso, C17 : 0 iso 3OH, C15 : 1 iso G, Summed Feature 3 (C16 : 1ω7c/C16 : 1ω6c), C15 : 0 iso 3OH and additionally, C15 : 0 anteiso among group II members. All analyses confirmed that strains of group I and II represent two novel species of the genus Flavobacterium, for which the names Flavobacterium chryseum sp. nov. (type strain CCM 8826^T=P3160^T=LMG 30615^T) and Flavobacterium psychroterrae sp. nov. (type strain CCM 8827^T=P3922^T=LMG 30616^T) are proposed.

Flavobacterium sediminilitoris sp. nov., isolated from a tidal flat

A Gram-stain-negative, facultatively aerobic, motile-by-gliding, non-flagellated and rod-shaped bacterial strain, designated YSM-43^T, was isolated from a tidal flat in Yeosu on the South Sea in the Republic of Korea. Strain YSM-43^T grew optimally at 30 °C and in the presence of 1.0-2.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences showed that strain YSM-43^T fell within the clade comprising type strains of Flavobacterium species, clustering with the type strains of Flavobacterium jejuense and Flavobacterium jumunjinense. It exhibited 16S rRNA gene sequence similarity values of 97.20 and 97.15 % to the type strains of F. jejuense and F. jumunjinense, respectively, and of less than 96.59 % to the type strains of the other Flavobacterium species. Strain YSM-43^T contained menaquinone-6 as the predominant menaquinone and iso-C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 1 G and iso-C15 : 0 3-OH as the major fatty acids. The major polar lipids were phosphatidylethanolamine and one unidentified lipid. The DNA G+C content of strain YSM-43^T was 29.8 mol% and its DNA-DNA relatedness values with type strains of F. jejuense and F. jumunjinense were 13 and 11 %, respectively. The differential phenotypic properties, together with the phylogenetic and genetic data, revealed that strain YSM-43^T is separate from other recognized species of the genus Flavobacterium. On the basis of the data presented, strain YSM-43^T is considered to represent a novel species of the genus Flavobacterium, for which the name Flavobacteriumsediminilitoris sp. nov. is proposed. The type strain is YSM-43^T (=KACC 19435^T=KCTC 62142^T=NBRC 113020^T).

Draft Genome Sequence of Flavobacterium sp. 316, a Baltic Sea Isolate Exhibiting a High Level of Resistance to Marine Stress Conditions

Here, we present the draft genome sequence of Flavobacterium sp. 316, isolated from brackish water of the Gulf of Gdańsk, southern Baltic Sea. The assembly contains 3,971,755 bp in 17 scaffolds. The sequence will facilitate postgenomic studies on bacterial stress responses in the challenging habitat of the Baltic Sea.