Flavobacterium beibuense sp. nov., isolated from marine sediment

Polyethylene terephthalate (PET)-degrading bacteria in the pelagic deep-sea sediments of the Pacific Ocean

Polyethylene terephthalate (PET) plastic pollution is widely found in deep-sea sediments. Despite being an international environmental issue, it remains unclear whether PET can be degraded through bioremediation in the deep sea. Pelagic sediments obtained from 19 sites across a wide geographic range in the Pacific Ocean were used to screen for bacteria with PET degrading potential. Bacterial consortia that could grow on PET as the sole carbon and energy source were found in 10 of the 19 sites. These bacterial consortia showed PET removal rate of 1.8%-16.2% within two months, which was further confirmed by the decrease of carbonyl and aliphatic hydrocarbon groups using attenuated total reflectance-Fourier-transform infrared analysis (ATR-FTIR). Analysis of microbial diversity revealed that Alcanivorax and Pseudomonas were predominant in all 10 PET degrading consortia. Meanwhile, Thalassospira, Nitratireductor, Nocardioides, Muricauda, and Owenweeksia were also found to possess PET degradation potential. Metabolomic analysis showed that Alcanivorax sp. A02-7 and Pseudomonas sp. A09-2 could turn PET into mono-(2-hydroxyethyl) terephthalate (MHET) even in situ stimulation (40 MPa, 10 °C) conditions. These findings widen the currently knowledge of deep-sea PET biodegrading process with bacteria isolates and degrading mechanisms, and indicating that the marine environment is a source of biotechnologically promising bacterial isolates and enzymes.

Flavobacterium poyangense sp. nov., an ammonifying bacterium isolated from a freshwater lake

A Gram-stain-negative, aerobic, non-spore-forming, nonmotile, rod-shaped, and yellow-pigmented bacterium, designated strain JXAS1T, was isolated from a freshwater sample collected from Poyang Lake in China. Phylogenetic analysis based on 16S rRNA gene sequence revealed that the isolate belonged to the genus Flavobacterium, being closest to Flavobacterium pectinovorum DSM 6368T (98.61 %). The genome size of strain JXAS1T was 4.66 Mb with DNA G+C content 35.7 mol%. The average nucleotide identity and in silico DNA-DNA hybridization values between strain JXAS1T and its closest relatives were below the threshold values of 95 and 70 %, respectively. The strain contained menaquinone 6 (MK-6) as the predominant menaquinone and the major polar lipids were phosphatidylethanolamine, one unidentified glycolipid, and one unidentified polar lipid. The major fatty acids (>5 %) were iso-C15 : 0, summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c), C15 : 0, iso-C17 : 0 3OH, iso-C15 : 0 3OH, and summed feature 9 (iso-C17 : 1  ω9c and/or 10-methyl C16 : 0). Based on phylogenetic, genotypic, and phenotypic evidence, the isolated strain represents a new species in the genus Flavobacterium, and the name Flavobacterium poyangense is proposed. The type strain is JXAS1T (=GDMCC 1.1378T=KCTC 62719T).

Overproduction of Xanthophyll Pigment in Flavobacterium sp. JSWR-1 under Optimized Culture Conditions

Flavobacterium can synthesize xanthophyll, particularly the pigment zeaxanthin, which has significant economic value in nutrition and pharmaceuticals. Recently, the use of carotenoid biosynthesis by bacteria and yeast fermentation technology has shown to be very efficient and offers significant advantages in large-scale production, cost-effectiveness, and safety. In the present study, JSWR-1 strain capable of producing xanthophyll pigment was isolated from a freshwater reservoir in Wanju-gun, Republic of Korea. Based on the morphological, physiological, and molecular characteristics, JSWR-1 classified as belonging to the Flavobacterium species. The bacterium is strictly aerobic, Gram-negative, rod-shaped, and psychrophilic. The completed genome sequence of the strain Flavobacterium sp. JSWR-1 is predicted to be a single circular 3,425,829-bp chromosome with a G+C content of 35.2% and 2,941 protein-coding genes. The optimization of carotenoid production was achieved by small-scale cultivation, resulting in zeaxanthin being identified as the predominant carotenoid pigment. The enhancement of zeaxanthin biosynthesis by applying different light-irradiation, variations in pH and temperature, and adding carbon and nitrogen supplies to the growth medium. A significant increase in intracellular zeaxanthin concentrations was also recorded during fed-batch fermentation achieving a maximum of 16.69 ± 0.71 mg/l, corresponding to a product yield of 4.05 ± 0.15 mg zeaxanthin per gram cell dry weight. Batch and fed-batch culture extracts exhibit significant antioxidant activity. The results demonstrated that the JSWR-1 strain can potentially serve as a source for zeaxanthin biosynthesis.

Characteristics and adaptability of Flavobacterium panici BSSL-CR3 in tidal flat revealed by comparative genomic and enzymatic analysis

Tidal flat microbes play an important ecological role by removing organic pollutants and providing an energy source. However, bacteria isolated from tidal flats and their genomes have been scarcely reported, making it difficult to elucidate which genes and pathways are potentially involved in the above roles. In this study, strain BSSL-CR3, the third reported species among the tidal flat Flavobacterium was analyzed using whole-genome sequencing to investigate its adaptability and functionality in tidal flats. BSSL-CR3 is comprised of a circular chromosome of 5,972,859 bp with a GC content of 33.84%. Genome annotation and API ZYM results showed that BSSL-CR3 has a variety of secondary metabolic gene clusters and enzyme activities including α-galactosidase. BSSL-CR3 had more proteins with a low isoelectric point (pI) than terrestrial Flavobacterium strains, and several genes related to osmotic regulation were found in the genomic island (GI). Comparative genomic analysis with other tidal flat bacteria also revealed that BSSL-CR3 had the largest number of genes encoding Carbohydrate Active EnZymes (CAZymes) which are related to algae degradation. This study will provide insight into the adaptability of BSSL-CR3 to the tidal flats and contribute to facilitating future comparative analysis of bacteria in tidal flats.

Degradation potential of alkanes by diverse oil-degrading bacteria from deep-sea sediments of Haima cold seep areas, South China Sea

Marine oil spills are a significant concern worldwide, destroying the ecological environment and threatening the survival of marine life. Various oil-degrading bacteria have been widely reported in marine environments in response to marine oil pollution. However, little information is known about culturable oil-degrading bacteria in cold seep of the deep-sea environments, which are rich in hydrocarbons. This study enriched five oil-degrading consortia from sediments collected from the Haima cold seep areas of the South China Sea. Parvibaculum, Erythrobacter, Acinetobacter, Alcanivorax, Pseudomonas, Marinobacter, Halomonas, and Idiomarina were the dominant genera. Further results of bacterial growth and degradation ability tests indicated seven efficient alkane-degrading bacteria belonging to Acinetobacter, Alcanivorax, Kangiella, Limimaricola, Marinobacter, Flavobacterium, and Paracoccus, whose degradation rates were higher in crude oil (70.3–78.0%) than that in diesel oil (62.7–66.3%). From the view of carbon chain length, alkane degradation rates were medium chains > long chains > short chains. In addition, Kangiella aquimarina F7, Acinetobacter venetianus F1, Limimaricola variabilis F8, Marinobacter nauticus J5, Flavobacterium sediminis N3, and Paracoccus sediminilitoris N6 were first identified as oil-degrading bacteria from deep-sea environments. This study will provide insight into the bacterial community structures and oil-degrading bacterial diversity in the Haima cold seep areas, South China Sea, and offer bacterial resources to oil bioremediation applications.

Comparison of bacterial and archaeal communities in two fertilizer doses and soil compartments under continuous cultivation system of garlic

Soil microbial communities are affected by interactions between agricultural management (e.g., fertilizer) and soil compartment, but few studies have considered combinations of these factors. We compared the microbial abundance, diversity and community structure in two fertilizer dose (high vs. low NPK) and soil compartment (rhizosphere vs. bulk soils) under 6-year fertilization regimes in a continuous garlic cropping system in China. The soil contents of NO3- and available K were significantly higher in bulk soil in the high-NPK. The 16S rRNA gene-based bacterial and archaeal abundances were positively affected by both the fertilizer dose and soil compartment, and were higher in the high-NPK fertilization and rhizosphere samples. High-NPK fertilization increased the Shannon index and decreased bacterial and archaeal richness, whereas the evenness was marginally positively affected by both the fertilizer dose and soil compartment. Soil compartment exerted a greater effect on the bacterial and archaeal community structure than did the fertilization dose, as demonstrated by both the nonmetric multidimensional scaling and redundancy analysis results. We found that rhizosphere effects significantly distinguished 12 dominant classes of bacterial and archaeal communities, whereas the fertilizer dose significantly identified four dominant classes. In particular, a Linear Effect Size analysis showed that some taxa, including Alphaproteobacteria, Rhizobiales, Xanthomonadaceae and Flavobacterium, were enriched in the garlic rhizosphere of the high-NPK fertilizer samples. Overall, the fertilizer dose interacted with soil compartment to shape the bacterial and archaeal community composition, abundance, and biodiversity in the garlic rhizosphere. These results provide an important basis for further understanding adaptive garlic-microbe feedback, reframing roots as a significant moderating influence in agricultural management and shaping the microbial community.

Flavobacterium alkalisoli sp. nov., isolated from rhizosphere soil of Suaeda salsa

A Gram-negative, strictly aerobic, gliding motility, none-spore forming, yellow, rods bacterial strain, designated XS-5T, was isolated from rhizosphere soil of Suaeda salsa, in Tumd Right Banner, Inner Mongolia, PR China. A phylogenetic tree based on the 16S rRNA gene sequences and the phylogenomic tree both showed that strain XS-5T clustered with Flavobacterium beibuense F44-8T (shared 97.2 % of 16S rRNA gene similarity) and Flavobacterium rakeshii FCS-5T (97.6 %), and shared <96.0 % of 16S rRNA gene similarities with all other type strains. Strain XS-5T contained MK-6 as the major respiratory quinone. Its major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and an unidentified lipid; and the major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 0, iso-C15 : 0 3-OH, Summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1  ω7c), and Summed feature 9 (iso-C17 : 1  ω9c and/or C16 : 0 10-methyl). The genome consisted of a 3 985 855 bp circular chromosome, with a G+C content of 37.9 mol%, predicting 3616 coding sequences genes, 45 tRNA genes and three rRNA operons. The average nucleotide identity, amino acid identity and digital DNA–DNA hybridization values of strain XS-5T to F. beibuense F44-8T and F. rakeshii FCS-5T were 79.2 and 79.2 %, 81.7 and 81.6 %, 22.3 and 22.2 %, respectively. The results of phylogenetic, physiological and biochemical tests allowed the discrimination of strain XS-5T from its phylogenetic relatives. Flavobacterium alkalisoli sp. nov. is therefore proposed with strain XS-5T (=CGMCC 1.17077T=KCTC 72459T) as the type strain.

Genomic diversity in flavobacterial pathogens of aquatic origin

Flavobacterium species are considered important fish pathogens in wild and cultured fish throughout the world. They can cause acute, subacute, and chronic infections, which are mainly characterized by gill damage, skin lesions, and deep necrotic ulcerations. Primarily, three Flavobacterium species, F. branchiophilum, F. columnare, and F. psychrophilum, have been reported to cause substantial losses to freshwater fish. In this study, we evaluated genomes of 86 Flavobacterium species isolated from aquatic hosts (mainly fish) to identify their unique and shared genome features. Our results showed that F. columnare genomes cluster into four different genetic groups. In silico secretion system analysis identified that all genomes carry type I (T1SS) and type IX (T9SS) secretion systems, but the number of type I secretion system genes shows diversity between species. F. branchiophilum, F. araucananum, F. chilense, F. spartansii, and F. tructae genomes have full type VI secretion system (T6SS). F. columnare, F. hydatis, and F. plurextorum carry partial T6SS with some of the T6SS genes missing. F. columnare, F. araucananum, F. chilense, F. spartansii, F. araucananum, F. tructae, Flavobacterium sp., F. crassostreae, F. succinicans, F. hydatis, and F. plurextorum carry most of the type IV secretion system genes (T4SS). F. columnare genetic groups 1 and 2, Flavobacterium sp., and F. crassostreae encode the least number of antibiotic resistance elements. F. hydatis, F. chilense, and F. plurextorum encode the greatest number of antibiotic resistance genes. Additionally, F. spartansii, F. araucananum, and chilense encode the greatest number of virulence genes while Flavobacterium sp. and F. crassostreae encode the least number of virulence genes. In conclusion, comparative genomics of Flavobacterium species of aquatic origin will help our understanding of Flavobacterium pathogenesis.

Flavobacterium knui sp. nov., a novel member of the family Flavobacteriaceae

A Gram-stain negative, non-motile, rod-shaped bacterial strain, designated 2-56^T, was isolated from water and characterized taxonomically using a polyphasic approach. Comparative 16S rRNA gene sequence analysis showed that strain 2-56^T belongs to the family Flavobacteriaceae in the phylum Bacteroidetes and is closely related to Flavobacterium paronense KNUS1^T (98.4%) and Flavobacterium collinsense 4-T-2^T (96.7%). The G + C content of the genomic DNA of strain 2-56^T was 33.4 mol%. The isolate contained MK-6 as the predominant respiratory quinone, and iso-C_15:1 G (15.9%), iso-C_15:0 (15.8%), iso-C_17:0 3-OH (10.7%), and iso-C_15:0 3-OH (9.6%) were the major fatty acids. The major polar lipids were phosphatidylethanolamine and an unidentified lipid. The phenotypic and chemotaxonomic data support the affiliation of strain 2-56^T with the genus Flavobacterium. However, the DNA-DNA relatedness between the isolate and F. paronense and F. collinsense were 35.7 and 21.5%, respectively, clearly showing that strain 2-56^T is not related to them at the species level. Strain 2-56^T could be clearly differentiated from its close neighbours on the basis of its phenotypic, genotypic and chemotaxonomic features. Therefore, strain 2-56^T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium knui sp. nov. is proposed. The type strain is 2-56^T (= KCTC 62061^T = JCM 32247^T).

Flavobacterium zaozhuangense sp. nov., a new member of the family Flavobacteriaceae, isolated from metolachlor-contaminated soil

Strain ZZ-8^T, a Gram-negative, aerobic, non-spore-forming, non-motile, yellow-pigmented, rod-shaped bacterium, was isolated from metolachlor-contaminated soil in China. The taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ZZ-8^T is a member of the genus Flavobacterium and shows high sequence similarity to Flavobacterium humicola UCM-46^T (97.2%) and Flavobacterium pedocola UCM-R36^T (97.1%), and lower (< 97%) sequence similarity to other known Flavobacterium species. Chemotaxonomic analysis revealed that strain ZZ-8^T possessed MK-6 as the major respiratory quinone; and iso-C_15:0 (28.5%), summed feature 9 (iso-C_17:1 w9c/C_16:0 10-methyl, 22.9%), iso-C_17:0 3-OH (17.0%), iso-C_15:0 3-OH (8.9%), iso-C_15:1 G (8.6%) and summed feature 3 (C_16:1 w7c/C_16:1 w6c, 5.7%) as the predominant fatty acids. The polar lipids of strain ZZ-8^T were determined to be lipids, a glycolipid, aminolipids and phosphatidylethanolamine. Strain ZZ-8^T showed low DNA-DNA relatedness with F. pedocola UCM-R36^T (43.23 ± 4.1%) and F. humicola UCM-46^T (29.17 ± 3.8%). The DNA G+C content was 43.3 mol%. Based on the phylogenetic and phenotypic characteristics, chemotaxonomic data and DNA-DNA hybridization, strain ZZ-8^T is considered a novel species of the genus Flavobacterium, for which the name Flavobacterium zaozhuangense sp. nov. (type strain ZZ-8^T = KCTC 62315 ^T = CCTCC AB 2017243^T) is proposed.

Flavobacterium limi sp. nov., isolated from forest mud

A Gram-stain-negative, aerobic, non-motile, yellow and rod-shaped bacterial strain was isolated from forest mud located at Kyung Hee University, South Korea. Strain THG-AG6.4^T grew at 10-35 °C, pH 6.0-9.5 and in the presence of 0-1.5 % (w/v) NaCl. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that strain THG-AG6.4^T was most closely related to Flavobacterium gyeonganense HME 7524^T (97.66 %), Flavobacterium defluvii EMB 117^T (96.93 %) and Flavobacterium arsenitoxidans S2-3H^T (96.80 %). The DNA G+C content of strain THG-AG6.4^T was 30.2 mol%. The DNA-DNA relatedness values between strain THG-AG6.4^T and its closest phylogenetic neighbour, F. gyeonganense HME 7524^T, were below 61.0 %. The predominant quinone of strain THG-AG6.4^T was MK-6. The major polar lipids were phosphatidylethanolamine, an unidentified phospholipid, five unidentified glycolipids, phosphatidylserine, an unidentified lipid, an unidentified aminophospholipid, two unidentified aminolipids and two unidentified aminoglycolipids. The major fatty acids were C16 : 0, C18 : 0 10-methyl, summed feature 3 and C18 : 1ω9c. The major polyamine was homospermidine. On the basis of the phenotypic, genotypic and phylogenetic characterization of strain THG-AG6.4^T, it is concluded that the isolate represents a novel species of the genus Flavobacterium, for which the name Flavobacterium limi sp. nov. is proposed, with THG-AG6.4^T as the type strain (=KACC 18851^T=CGMCC 1.16060^T).

Flavobacterium soyangense sp. nov., a psychrotolerant bacterium, isolated from an oligotrophic freshwater lake

A bacterial strain, designated IMCC26223T, was isolated from an oligotrophic freshwater lake, Lake Soyang, Korea. Cells of strain IMCC26223T were Gram-staining negative, strictly aerobic, non-motile and short-rod-shaped. Growth occurred at pH 6-8 (optimum, pH 7.0), at 4-25 °C (optimum, 15 °C) and with 0-0.5 % (w/v) NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain IMCC26223T was identified as a member of the genus Flavobacterium and most closely related to Flavobacterium fluvii H7T (97.6 %), Flavobacterium segetis AT1048T (97.5 %) and Flavobacterium weaverense AT1042T (97.2 %). DNA-DNA relatedness between strain IMCC26223T and F. fluvii H7T was 41.5-51.7 % in the reciprocal hybridization. Strain IMCC26223T contained MK-6 as the major respiratory quinone. The major cellular fatty acids consisted of C16 : 0, iso-C15 : 0, anteiso-C15 : 0 and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), and the polar lipids were phosphatidylethanolamine, an unidentified aminolipid and two unidentified lipids. The DNA G+C content of strain IMCC26223T was 34.5 mol%. On the basis of 16S rRNA gene phylogeny and phenotypic characterization, strain IMCC26223T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium soyangense sp. nov., is proposed. The type strain is IMCC26223T (=KCTC 52245T=JCM 31384T).

Comparative genome analysis of the Flavobacteriales bacterium strain UJ101, isolated from the gut of Atergatis reticulatus

Here we report the comparative genomic analysis of strain UJ101 with 15 strains from the family Flavobacteriaceae, using the CGExplorer program. Flavobacteriales bacterium strain UJ101 was isolated from a xanthid crab, Atergatis reticulatus, from the East Sea near Korea. The complete genome of strain UJ101 is a 3,074,209 bp, single, circular chromosome with 30.74% GC content. While the UJ101 genome contains a number of annotated genes for many metabolic pathways, such as the Embden-Meyerhof pathway, the pentose phosphate pathway, the tricarboxylic acid (TCA) cycle, and the glyoxylate cycle, genes for the Entner-Douddoroff pathway are not found in the UJ101 genome. Overall, carbon fixation processes were absent but nitrate reduction and denitrification pathways were conserved. The UJ101 genome was compared to genomes from other marine animals (three invertebrate strains and 5 fish strains) and other marine animal- derived genera. Notable results by genome comparisons showed that UJ101 is capable of denitrification and nitrate reduction, and that biotin-thiamine pathway participation varies among marine bacteria; fish-dwelling bacteria, freeliving bacteria, invertebrate-dwelling bacteria, and strain UJ101. Pan-genome analysis of the 16 strains in this study included 7,220 non-redundant genes that covered 62% of the pan-genome. A core-genome of 994 genes was present and consisted of 8% of the genes from the pan-genome. Strain UJ101 is a symbiotic hetero-organotroph isolated from xanthid crab, and is a metabolic generalist with nitrate-reducing abilities but without the ability to synthesize biotin. There is a general tendency of UJ101 and some fish pathogens to prefer thiamine-dependent glycolysis to gluconeogenesis. Biotin and thiamine auxotrophy or prototrophy may be used as important markers in microbial community studies.

Taxonomy and systematics of plant probiotic bacteria in the genomic era

Recent decades have predicted significant changes within our concept of plant endophytes, from only a small number specific microorganisms being able to colonize plant tissues, to whole communities that live and interact with their hosts and each other. Many of these microorganisms are responsible for health status of the plant, and have become known in recent years as plant probiotics. Contrary to human probiotics, they belong to many different phyla and have usually had each genus analysed independently, which has resulted in lack of a complete taxonomic analysis as a group. This review scrutinizes the plant probiotic concept, and the taxonomic status of plant probiotic bacteria, based on both traditional and more recent approaches. Phylogenomic studies and genes with implications in plant-beneficial effects are discussed. This report covers some representative probiotic bacteria of the phylum Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes, but also includes minor representatives and less studied groups within these phyla which have been identified as plant probiotics.

Complete Genome Sequence of Flavobacteriales Bacterium Strain UJ101 Isolated from a Xanthid Crab

Flavobacteriales bacterium strain UJ101 was isolated from a xanthid crab species collected from the East Sea of Korea. Here, we report the complete genome sequence of strain UJ101 for the study of major metabolic pathways related to microbial species from marine invertebrate species.

New host record of five Flavobacterium species associated with tropical fresh water farmed fishes from North India

Yellow pigmented, filamentous, Gram-negative bacteria belonging to genus Flavobacterium are commonly associated with infections in stressed fish. In this study, inter-species diversity of Flavobacterium was studied in apparently healthy freshwater farmed fishes. For this, ninety one yellow pigmented bacteria were isolated from skin and gill samples (n = 38) of three farmed fish species i.e. Labeo rohita, Catla catla and Cyprinus carpio. Among them, only twelve bacterial isolates (13.18%) were identified as Flavobacterium spp. on the basis of morphological, biochemical tests, partial 16S rDNA gene sequencing and phylogenetic analysis. On the basis of 16S rDNA gene sequencing, all the 12 isolates were 97.6-100% similar to six different formally described species of genus Flavobacterium. The 16S rDNA based phylogenetic analysis grouped these strains into six different clades. Of the 12 isolates, six strains (Fl9S1-6) grouped with F. suncheonense, two strains (Fl6I2, Fl6I3) with F. indicum and the rest four strains (Fl1A1, Fl2G1, Fl3H1 and Fl10T1) clustered with F. aquaticum, F. granuli, F. hercynium and F. terrae, respectively. None of these species except, F. hercynium were previously reported from fish. All the isolated Flavobacterium species possessed the ability of adhesion and biofilm formation to colonize the external surface of healthy fish. The present study is the first record of tropical freshwater farmed fishes as hosts to five environmentally associated species of the Flavobacterium.

Not All Particles Are Equal: The Selective Enrichment of Particle-Associated Bacteria from the Mediterranean Sea

We have used two metagenomic approaches, direct sequencing of natural samples and sequencing after enrichment, to characterize communities of prokaryotes associated to particles. In the first approximation, different size filters (0.22 and 5 μm) were used to identify prokaryotic microbes of free-living and particle-attached bacterial communities in the Mediterranean water column. A subtractive metagenomic approach was used to characterize the dominant microbial groups in the large size fraction that were not present in the free-living one. They belonged mainly to Actinobacteria, Planctomycetes, Flavobacteria and Proteobacteria. In addition, marine microbial communities enriched by incubation with different kinds of particulate material have been studied by metagenomic assembly. Different particle kinds (diatomaceous earth, sand, chitin and cellulose) were colonized by very different communities of bacteria belonging to Roseobacter, Vibrio, Bacteriovorax, and Lacinutrix that were distant relatives of genomes already described from marine habitats. Besides, using assembly from deep metagenomic sequencing from the particle-specific enrichments we were able to determine a total of 20 groups of contigs (eight of them with >50% completeness) and reconstruct de novo five new genomes of novel species within marine clades (>79% completeness and <1.8% contamination). We also describe for the first time the genome of a marine Rhizobiales phage that seems to infect a broad range of Alphaproteobacteria and live in habitats as diverse as soil, marine sediment and water column. The metagenomic recruitment of the communities found by direct sequencing of the large size filter and by enrichment had nearly no overlap. These results indicate that these reconstructed genomes are part of the rare biosphere which exists at nominal levels under natural conditions.

Flavobacterium lutivivi sp. nov., isolated from activated sludge

A Gram-stain-negative, strictly aerobic, yellow, rod-shaped bacterium, designated strain HQQ^T, was isolated from a municipal wastewater treatment plant in Hebei Province, PR China. Comparative 16S rRNA gene sequence analyses showed that strain HQQ^T is a member of the genus Flavobacterium and is closely related to 'Flavobacterium shanxiense' CCTCC AB 2014079^T (94.8 %) and Flavobacterium macrobrachii DSM 22219^T (94.7 %). Phylogenetic analysis showed that strain HQQ^T clustered with Flavobacterium fontis JCM 18212^T and Flavobacterium squillarum KCTC 23915^T. The polar lipid profile of strain HQQ^T revealed the presence of phosphatidylethanolamine, six unknown aminolipids, one unknown glycolipid and one unknown lipid and the only isoprenoid quinone was MK-6. The dominant fatty acids of strain HQQ^T were iso-C_15 : 0, C_15 : 0 and C_16 : 1ω7c. The DNA G+C content of strain HQQ^T is 32 mol%. On the basis of the phylogenetic and phenotypic data, strain HQQ^T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium lutivivi sp. nov. is proposed. The type strain is HQQ^T ( = CGMCC 1.15347^T = KCTC 42935^T).

High quality draft genomic sequence of Flavobacterium enshiense DK69(T) and comparison among Flavobacterium genomes

Flavobacterium enshiense DK69(T) is a Gram-negative, aerobic, rod-shaped, non-motile and non-flagellated bacterium that belongs to the family Flavobacteriaceae in the phylum Bacteroidetes. The high quality draft genome of strain DK69(T) was obtained and has a 3,375,260 bp genome size with a G + C content of 37.7 mol % and 2848 protein coding genes. In addition, we sequenced five more genomes of Flavobacterium type strains and performed a comparative genomic analysis among 12 Flavobacterium genomes. The results show some specific genes within the fish pathogenic Flavobacterium strains which provide information for further analysis the pathogenicity.

Flavobacterium jejuensis sp. nov., isolated from marine brown alga Ecklonia cava

A bacterial strain, designated EC11(T) was isolated from brown alga Ecklonia cava collected from Jeju Island, Korea. EC11(T) was identified as a Gram-negative, rod-shaped and yellow-pigmented bacterial strain. The strain EC11(T) grew over a temperature range of 10 °C to 30 °C (optimally at 25 °C), and a pH range of 6.0-10.5 (optimally at pH 7.5). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain EC11(T) belongs to the genus Flavobacterium. Strain EC11(T) shared close similarity with Flavobacterium jumunjinense HME7102(T) (96.4%), Flavobacterium dongtanense LW30(T) (95.8%), Flavobacterium haoranii LQY-7(T) (95.3%), and Flavobacterium urocaniciphilum (95.1%). The major fatty acids (> 5%) were iso-C17:0 3-OH (22.4%), iso-C15:0 3-OH (19.0%), C15:0 (12.4%), summed feature 3 (comprising C16:1 ω7c/ C16:1 ω6c; 9.78%), iso-C15:1 G (9.6%), and iso-C16:0 3-OH (9.0%). The DNA G+C content was 28.1 mol% and the strain contained MK-6 as the predominant menaquinone. The major polar lipids were phosphatidylethanolamine, two unknown aminolipids and three unknown polar lipids. Based on phenotypic, chemotaxonomic and phylogenetic analysis, strain EC11T represents a novel species of the Flavobacterium genus, for which the name Flavobacterium jejuensis sp. nov. is proposed. The type strain of F. jejuensis is EC11(T) (=KCTC 42149(T) = JCM 30735(T)).

Flavobacterium procerum sp. nov., isolated from freshwater

A Gram-reaction-negative, strictly aerobic, yellow-pigmented, rod-shaped bacterium, designated strain T3T, was isolated from freshwater of Chishui River flowing through Maotai town, Guizhou, south-west China. Analysis of the16S rRNA gene sequence indicated that strain T3T was a member of the genus Flavobacterium and closely related to Flavobacterium resistens DSM 19382T (96.8  %). The novel strain was able to grow at 10–34 °C (optimum 28 °C), pH 6.0–11.0 (optimum pH 8.0–9.0) and with 0–2.0  % (w/v) NaCl (optimum 0  %). The major polar lipids were phosphatidylethanolamine, two unknown glycolipids, five unknown aminolipids and four unidentified lipids, and the major respiratory quinone was MK-6. The predominant fatty acids were C16  :  1ω7c and/or C16  :  1ω6c and iso-C15  :  0. The DNA G+C content of the strain was 36 mol  %. Based on these data, strain T3T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium procerum sp. nov. is proposed. The type strain is T3T ( = CGMCC 1.12926T = JCM 30113T).

High quality draft genome sequence of Flavobacterium rivuli type strain WB 3.3-2(T) (DSM 21788(T)), a valuable source of polysaccharide decomposing enzymes

Flavobacterium rivuli Ali et al. 2009 emend. Dong et al. 2013 is one of about 100 species in the genus Flavobacterium (family Flavobacteriacae, phylum Bacteroidetes) with a validly published name, and has been isolated from the spring of a hard water rivulet in Northern Germany. Including all type strains of the genus Myroides and Flavobacterium into the 16S rRNA gene sequence phylogeny revealed a clustering of members of the genus Myroides as a monophyletic group within the genus Flavobacterium. Furthermore, F. rivuli WB 3.3-2^T and its next relatives seem more closely related to the genus Myroides than to the type species of the genus Flavobacterium, F. aquatile. The 4,489,248 bp long genome with its 3,391 protein-coding and 65 RNA genes is part of the GenomicEncyclopedia ofBacteria andArchaea project. The genome of F. rivuli has almost as many genes encoding carbohydrate active enzymes (151 CAZymes) as genes encoding peptidases (177). Peptidases comprised mostly metallo (M) and serine (S) peptidases. Among CAZymes, 30 glycoside hydrolase families, 10 glycosyl transferase families, 7 carbohydrate binding module families and 7 carbohydrate esterase families were identified. Furthermore, we found four polysaccharide utilization loci (PUL) and one large CAZy rich gene cluster that might enable strain WB 3.3-2^T to decompose plant and algae derived polysaccharides. Based on these results we propose F. rivuli as an interesting candidate for further physiological studies and the role of Bacteroidetes in the decomposition of complex polymers in the environment.

Flavobacterium daemonensis sp. nov., isolated from Daemo Mountain soil

A Gram-staining-negative, catalase- and oxidase-positive, obligately aerobic, motile by gliding, bright yellow and rod-shaped bacterial strain was isolated from soil of Daemo Mountain (Daemosan) in Seoul, Republic of Korea. Its taxonomic position was investigated by using a polyphasic study. On the basis of 16S rRNA gene sequence comparisons, strain THG–DJ7T was found to be most closely related to Flavobacterium denitrificans ED5T (97.9 % sequence similarity), Flavobacterium ginsenosidimutans THG 01T (97.6 %), Flavobacterium kyungheensis THG-107T (97.5 %), Flavobacterium anhuiense D3T (97.1 %) and Flavobacterium ginsengisoli DCY54T (97.0 %). The DNA–DNA relatedness between strain THG–DJ7T and its phylogenetically closest neighbours was below 40.0 %. The G+C content of the genomic DNA was determined to be 32.6 mol%. The only isoprenoid quinone detected in strain THG–DJ7T was menaquinone-6 (MK-6). The major component in the polyamine pattern was sym-homospermidine. The major polar lipids were found to be phosphatidylethanolamine, phosphatidyldimethylethanolamine, an unidentified aminophosphoglycolipid, phosphatidylserine and an unidentified lipid. The major fatty acids were identified as iso-C15 : 0, iso-C15 : 0 3-OH and summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c). These data support the affiliation of strain THG–DJ7T to the genus Flavobacterium . We report the phenotypic, genotypic and phylogenetic characterization of strain THG–DJ7T. Based on the findings presented, a novel species of the genus Flavobacterium , Flavobacterium daemonensis sp. nov. is proposed, with THG–DJ7T ( = KACC 17651T = JCM 19455T) as the type strain.

Emerging flavobacterial infections in fish: A review

Flavobacterial diseases in fish are caused by multiple bacterial species within the family Flavobacteriaceae and are responsible for devastating losses in wild and farmed fish stocks around the world. In addition to directly imposing negative economic and ecological effects, flavobacterial disease outbreaks are also notoriously difficult to prevent and control despite nearly 100 years of scientific research. The emergence of recent reports linking previously uncharacterized flavobacteria to systemic infections and mortality events in fish stocks of Europe, South America, Asia, Africa, and North America is also of major concern and has highlighted some of the difficulties surrounding the diagnosis and chemotherapeutic treatment of flavobacterial fish diseases. Herein, we provide a review of the literature that focuses on Flavobacterium and Chryseobacterium spp. and emphasizes those associated with fish.

Flavobacterium arsenitoxidans sp. nov., an arsenite-oxidizing bacterium from Thai soil

An arsenite-oxidizing bacterium, strain S2-3H(T), was isolated from arsenic-contaminated soil sample collected from Dantchaeng district, Suphanburi province, Thailand and was characterized based on polyphasic taxonomic study. The strain was observed to be a Gram-stain negative, aerobic, yellow pigmented, non-spore forming and rod-shaped bacterium. Major menaquinone was MK-6. Iso-C15:0, iso-C15:0 3OH, C16:1 ω7c/C16:1 ω6c, C16:0, iso-C17:0 3OH, and C16:0 3OH were the predominant cellular fatty acids. The polar lipid profile consisted of phosphatidylethanolamine, unidentified phospholipids and unidentified aminophospholipids. The DNA G+C content was 37.0 mol%. Phylogenetic analysis using 16S rRNA sequence showed that strain S2-3H(T) is affiliated to the genus Flavobacterium, and is closely related to F. defluvii KCTC 12612(T) (97.0 %) and F. johnsoniae NBRC 14942(T) (97.0 %). The strain S2-3H(T) could be clearly distinguished from the related Flavobacterium species by its physiological and biochemical characteristics as well as its phylogenetic position and DNA-DNA relatedness. Therefore, the strain represents a novel species of the genus Flavobacterium, for which the name Flavobacterium arsenitoxidans sp. nov. (type strain S2-3H(T) = KCTC 22507(T) = NBRC 109607(T) = PCU 331(T) = TISTR 2238(T)) is proposed.

Flavobacterium arsenatis sp. nov., a novel arsenic-resistant bacterium from high-arsenic sediment

A novel bacterial strain Z(T) was isolated from the high-arsenic sediment in Jianghan Plain, China. The strain was Gram-staining-negative, rod-shaped and formed yellow colonies. This bacterium is capable of tolerating arsenate and arsenite, with MICs of 40 mM and 20 mM, respectively. The strain also possesses catalase and does not produce oxidase. The nucleotide sequence of the 16S rRNA gene of the isolate showed the highest similarity (96.9%) to that of the type strain of Flavobacterium soli. On the basis of the 16S rRNA gene sequence analysis and the phenotypic properties of strain Z(T), it was assigned to the genus Flavobacterium. The major respiratory menaquinone was MK-6 and the predominant fatty acids were iso-C15:0, summed feature 3 (containing C16:1ω6c and/or C16:1ω7c) and iso-C15:1G. The major polar lipids were phosphatidylethanolamine, three uncharacterized aminophospholipids and four unidentified phospholipids. The DNA G+C content was 32.1 mol%. Based on the phenotypic and genotypic data presented in this article, it can be concluded that this isolate represents a novel species of the genus Flavobacterium, for which the name Flavobacterium arsenatis sp. nov. is proposed. The type strain is Z(T) ( = CCTCC AB 2013048(T) = KCTC 32397(T)).

Comparative genomic analysis indicates that niche adaptation of terrestrial Flavobacteria is strongly linked to plant glycan metabolism

Flavobacteria are important members of aquatic and terrestrial bacterial communities, displaying extreme variations in lifestyle, geographical distribution and genome size. They are ubiquitous in soil, but are often strongly enriched in the rhizosphere and phyllosphere of plants. In this study, we compared the genome of a root-associated Flavobacterium that we recently isolated, physiologically characterized and sequenced, to 14 additional Flavobacterium genomes, in order to pinpoint characteristics associated with its high abundance in the rhizosphere. Interestingly, flavobacterial genomes vary in size by approximately two-fold, with terrestrial isolates having predominantly larger genomes than those from aquatic environments. Comparative functional gene analysis revealed that terrestrial and aquatic Flavobacteria generally segregated into two distinct clades. Members of the aquatic clade had a higher ratio of peptide and protein utilization genes, whereas members of the terrestrial clade were characterized by a significantly higher abundance and diversity of genes involved in metabolism of carbohydrates such as xylose, arabinose and pectin. Interestingly, genes encoding glycoside hydrolase (GH) families GH78 and GH106, responsible for rhamnogalacturonan utilization (exclusively associated with terrestrial plant hemicelluloses), were only present in terrestrial clade genomes, suggesting adaptation of the terrestrial strains to plant-related carbohydrate metabolism. The Peptidase/GH ratio of aquatic clade Flavobacteria was significantly higher than that of terrestrial strains (1.7±0.7 and 9.7±4.7, respectively), supporting the concept that this relation can be used to infer Flavobacterium lifestyles. Collectively, our research suggests that terrestrial Flavobacteria are highly adapted to plant carbohydrate metabolism, which appears to be a key to their profusion in plant environments.

Flavobacterium noncentrifugens sp. nov., a psychrotolerant bacterium isolated from glacier meltwater

A non-motile, Gram-stain-negative bacterium, designated R-HLS-17T, was isolated from the meltwater of Hailuogou Glacier located in Sichuan province, south-west China. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate belonged to the genus Flavobacterium , with the closest relatives being Flavobacterium antarcticum JCM 12383T (95.5 % 16S rRNA gene sequence similarity), F. omnivorum JCM 11313T (95.0 %) and F. fryxellicola LMG 22022T (95.2 %). Growth occurred at 0–29 °C (optimum, 10–20 °C) and pH 6.0–8.5 (optimum, 7.0–8.0). The DNA G+C content was 46.5 mol%. The major cellular fatty acids were iso-C15 : 0, iso-C15 : 1 G, summed feature 9 (comprising iso-C17 : 1ω9c and/or 10-methyl C16 : 0), iso-C17 : 0 3-OH and iso-C15 : 0 3-OH. The predominant menaquinone was MK-6. Based on the genotypic and phenotypic characteristics, we propose that strain R-HLS-17T represents a novel species of the genus Flavobacterium , Flavobacterium noncentrifugens sp. nov. The type strain is R-HLS-17T ( = CGMCC 1.10076T = NBRC 108844T).

Flavobacterium hauense sp. nov., isolated from soil and emended descriptions of Flavobacterium subsaxonicum, Flavobacterium beibuense and Flavobacterium rivuli

A strictly aerobic, Gram-staining-negative, rod-shaped, non-motile, yellow-pigmented bacterial strain, designated BX12(T), was isolated from soil collected from the peak area of Wudang Mountain in the city of Shiyan, Hubei province, China. Phylogenetic analysis of the 16S rRNA gene sequences showed that strain BX12(T) was most closely related to Flavobacterium subsaxonicum WB 4.1-42(T) (95.9% 16S rRNA gene sequence similarity), followed by Flavobacterium beibuense F44-8(T) (95.6%) and Flavobacterium rivuli WB 3.3-2(T) (94.1%). The major fatty acids (≥5%) of strain BX12(T) were summed feature 3 (comprising C(16:1)ω7c and/or C(16:1)ω6c), iso-C(15:0), C(16:0), iso-C(17:0) 3-OH, and C(16:0) 3-OH. The major polar lipid was phosphatidylethanolamine, and the major respiratory quinone was menaquinone-6. The genomic DNA G+C content was 43.9 mol%. On the basis of a high number of phenotypic differentiating properties and phylogenetic uniqueness, strain BX12(T) represents a novel species of the genus Flavobacterium for which the name Flavobacterium hauense sp. nov. is proposed. The type strain is BX12(T) ( =CCTCC AB 2012197(T) =KCTC 32147(T)). Emended descriptions of Flavobacterium subsaxonicum, Flavobacterium beibuense and Flavobacterium rivuli are also proposed.

Flavobacterium yanchengense sp. nov., isolated from soil

A Gram-stain-negative, non-spore-forming, rod-shaped bacterial strain, hg(T), resembling members of the genus Flavobacterium, was isolated from soil, and subjected to a taxonomic study using a polyphasic approach. Strain hg(T) grew optimally at pH 7.0 and 30 °C in the presence of 1 % (w/v) NaCl. It contained MK-6 as the predominant menaquinone and iso-C15 : 0 and iso-C17 : 0 3-OH as the major fatty acids. The DNA G+C content was 34 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain hg(T) belonged to the genus Flavobacterium. Levels of 16S rRNA gene sequence similarity between strain hg(T) and the type strains of species of the genus Flavobacterium were below 94.7 %. Strain hg(T) differed from phylogenetically related species of the genus Flavobacterium in several phenotypic characteristics. On the basis of phenotypic and phylogenetic distinctiveness, strain hg(T) (= CCTCC AB 2012099(T) = KACC 16855(T)) was classified in the genus Flavobacterium as the type strain of a novel species, for which the name Flavobacterium yanchengense sp. nov. is proposed.

Flavobacterium ummariense sp. nov., isolated from hexachlorocyclohexane-contaminated soil, and emended description of Flavobacterium ceti Vela et al. 2007

A Gram-negative, strictly aerobic, yellow bacterial strain, designated DS-12T, was isolated from hexachlorocyclohexane-contaminated soil in Lucknow, Uttar Pradesh, India. Strain DS-12T showed the highest 16S rRNA gene sequence similarity with Flavobacterium ceti 454-2T (94.2 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain DS-12T belonged to the genus Flavobacterium . Strain DS-12T produced flexirubin-type pigments. Gliding motility was not observed. The major fatty acids of strain DS-12T were iso-C15 : 0 (48.0 %), summed feature 9 (comprising iso-C17 : 1ω9c and/or C16 : 0 10-methyl; 19.3 %), iso-C17 : 0 3-OH (8.5 %) and summed feature 3 (comprising one or more of C16 : 1ω7c, C16 : 1ω6c and iso-C15 : 0 2-OH; 7.2 %). The only respiratory quinone was menaquinone-6 and the major polyamine was homospermidine. Strain DS-12T contained phosphatidyldimethylethanolamine, phosphatidylserine, phosphatidylethanolamine, one unknown phospholipid and one unknown aminolipid. The DNA G+C content was 37.4 mol%. Phylogenetic inference and phenotypic properties indicated that strain DS-12T represents a novel species of the genus Flavobacterium , for which the name Flavobacterium ummariense sp. nov. is proposed. The type strain is DS-12T ( = CCM 7847T  = MTCC 10766T). An emended description of Flavobacterium ceti is also given.

Flavobacterium compostarboris sp. nov., isolated from leaf-and-branch compost, and emended descriptions of Flavobacterium hercynium , Flavobacterium resistens and Flavobacterium johnsoniae

A strictly aerobic, Gram-negative, yellow-pigmented, non-spore-forming rod, designated 15C3T, was isolated from aerobic leaf-and-branch compost at EXPO Park in Osaka, Japan. Growth was observed at 9–33 °C (optimum 25 °C) and pH 5.6–7.9 (optimum pH 6.1–7.0). No growth occurred with >2 % (w/v) NaCl. Strain 15C3T reduced nitrate to nitrogen and showed catalase activity but not oxidase activity. The predominant fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (comprising C16 : 1ω7c and/or iso-C15 : 0 2-OH). The isolate contained phosphatidylethanolamine as the major polar lipid and menaquinone-6 as the major respiratory quinone. The G+C content of the genomic DNA of strain 15C3T was 33.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 15C3T belonged to the genus Flavobacterium and was most closely related to Flavobacterium hercynium WB 4.2-33T (96.9 % sequence similarity). On the basis of phenotypic and phylogenetic distinctiveness, strain 15C3T is considered to represent a novel species in the genus Flavobacterium , for which the name Flavobacterium compostarboris sp. nov. is proposed. The type strain is 15C3T ( = KACC 14224T  = JCM 16527T). Emended descriptions of F. hercynium , Flavobacterium resistens and Flavobacterium johnsoniae are also given.

Flavobacterium rakeshii sp. nov., isolated from marine sediment, and emended description of Flavobacterium beibuense Fu et al. 2011

A Gram-negative, non-motile bacterial strain that formed straight rods and straw yellow colonies, designated FCS-5(T), was isolated from a marine sediment from the Arabian Sea. The isolate exhibited most of the phenotypic properties expected for a member of the genus Flavobacterium. The major fatty acids were iso-C(15:0), iso-C(17:0) 3-OH, C(17:1)ω9c and summed feature 3 (comprising iso-C(15:0) 2-OH and/or C(16:1)ω7c). The only isoprenoid quinone was MK-6. The only polyamine was homospermidine and the major polar lipid was phosphatidylethanolamine. The G+C content of the genomic DNA was 32.4 mol%. According to 16S rRNA gene sequence analysis, strain FCS-5(T) belonged to the genus Flavobacterium and exhibited 99.3% 16S rRNA gene sequence similarity with Flavobacterium beibuense F44-8(T) and 90.9-94.6% sequence similarity with other members of the genus Flavobacterium. The results of physiological and biochemical tests allowed the discrimination of the isolate from its phylogenetic relatives. Strain FCS-5(T) is a representative of a novel species of the genus Flavobacterium, for which the name Flavobacterium rakeshii sp. nov. is proposed. The type strain is FCS-5(T) ( = MTCC 10967(T) = JCM 17928(T)). An emended description of F. beibuense is also proposed.