Flavobacterium zhairuonensis sp. nov., a gliding bacterium isolated from marine sediment of the East China Sea

Three novel species of the genus Flavobacterium, Flavobacterium odoriferum sp. nov., Flavobacterium fragile sp. nov. and Flavobacterium luminosum sp. nov., isolated from activated sludge

Three Gram-stain-negative, rod-shaped, non-spore-forming bacteria were isolated from activated sludge samples. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that the three strains, designated HXWNR29T, HXWNR69T and HXWNR70T, had the highest sequence similarity to the type strains Flavobacterium cheniae NJ-26T, Flavobacterium channae KSM-R2A30T and Flavobacterium amniphilum KYPY10T with similarities of 97.66 %, 98.66 and 98.14 %, respectively. The draft genomes of these three strains were 2.93 Mbp (HXWNR29T), 2.69 Mbp (HXWNR69T) and 2.65 Mbp (HXWNR70T) long with DNA G+C contents of 31.84 %, 32.83 % and 34.66 %, respectively. These genomes contained many genes responsible for carbohydrate degradation and antibiotic resistance. The major fatty acids (>5 %) included iso-C15 : 0, iso-C15 : 0 3-OH and iso-C17 : 0 3-OH. The major menaquinone was MK-6 for all the three strains. The average nucleotide identity (ANI; 72.7-88.5 %) and digital DNA-DNA hybridization (dDDH; 19.6-35.3 %) results further indicated that these three strains represented three novel species within the genus Flavobacterium, for which the names Flavobacterium odoriferum sp. nov. (type strain HXWNR29T = KCTC 92446T = CGMCC 1.61821T), Flavobacterium fragile sp. nov. (type strain HXWNR69T = KCTC 92468T = CGMCC 1.61442T) and Flavobacterium luminosum sp. nov. (type strain HXWNR70T = KCTC 92447T = CGMCC 1.61443T) are proposed.

Ten Novel Species Belonging to the Genus Flavobacterium, Isolated from Freshwater Environments: F. praedii sp. nov., F. marginilacus sp. nov., F. aestivum sp. nov., F. flavigenum sp. nov., F. luteolum sp. nov., F. gelatinilyticum sp. nov., F. aquiphilum sp. nov., F. limnophilum sp. nov., F. lacustre sp. nov., and F. eburneipallidum sp. nov

Eleven bacterial strains were isolated from freshwater environments and identified as Flavobacterium based on 16S rRNA gene sequence analyses. Complete genome sequences of the 11 strains ranged from 3.45 to 5.83 Mb with G + C contents of 33.41-37.31%. The average nucleotide identity (ANI) values showed that strains IMCC34515^T and IMCC34518 belonged to the same species, while the other nine strains represented each separate species. The ANI values between the strains and their closest Flavobacterium species exhibited ≤ 91.76%, indicating they represent each novel species. All strains had similar characteristics such as being Gram-stain-negative, rod-shaped, and contained iso-C_15:0 as the predominant fatty acid, menaquinone-6 as the respiratory quinone, and phosphatidylethanolamine and aminolipids as major polar lipids. Genomic, phylogenetic, and phenotypic characterization confirmed that the 11 strains were distinct from previously recognized Flavobacterium species. Therefore, Flavobacterium praedii sp. nov. (IMCC34515^T = KACC 22282 ^T = NBRC 114937 ^T), Flavobacterium marginilacus sp. nov. (IMCC34673^T = KACC 22284 ^T = NBRC 114940 ^T), Flavobacterium aestivum sp. nov. (IMCC34774^T = KACC 22285 ^T = NBRC 114941 ^T), Flavobacterium flavigenum sp. nov. (IMCC34775^T = KACC 22286 ^T = NBRC 114942 ^T), Flavobacterium luteolum sp. nov. (IMCC34776^T = KACC 22287 ^T = NBRC 114943 ^T), Flavobacterium gelatinilyticum sp. nov. (IMCC34777^T = KACC 22288 ^T = NBRC 114944 ^T), Flavobacterium aquiphilum sp. nov. (IMCC34779^T = KACC 22289 ^T = NBRC 114945 ^T), Flavobacterium limnophilum sp. nov. (IMCC36791^T = KACC 22290 ^T = NBRC 114947 ^T), Flavobacterium lacustre sp. nov. (IMCC36792^T = KACC 22291 ^T = NBRC 114948 ^T), and Flavobacterium eburneipallidum sp. nov. (IMCC36793^T = KACC 22292 ^T = NBRC 114949 ^T) are proposed as novel species.

Flavobacterium litorale sp. nov., isolated from red alga

A Gram-stain-negative and rod-shaped bacterial strain (WSW3-B6T) was isolated from red alga collected from the West Sea, Republic of Korea. Cells of strain WSW3-B6T were non-motile, aerobic and produced slightly yellow and mucoid colonies on marine agar. The strain grew optimally at 23–30 °C, with 0.5–4 % NaCl (w/v) and at pH 6.5–8.5. A phylogenetic analysis of the 16S rRNA gene revealed that strain WSW3-B6T belongs to the genus Flavobacterium within the family Flavobacteriaceae , having the highest sequence similarity to Flavobacterium arcticum SM1502T (96.7%), followed by Flavobacterium salilacus subsp. altitudinum LaA7.5T (96.2%) and Flavobacterium salilacus subsp. salilacus SaA2.12T (96.2%). The complete sequence of a circular chromosome of strain WSW3-B6T determined by combination of Oxford Nanopore and Illumina platforms comprised a total 2 725 095 bp with G+C content of 37.1 mol%. A comparative analysis based on the whole genome also showed the distinctiveness of strain WSW3-B6T. The average nucleotide identity (ANI) values between strain WSW3-B6T and the closest strains F. arcticum SM1502T, F. salilacus subsp. altitudinum LaA7.5T and F. salilacus subsp. salilacus SaA2.12T were 78.3, 77.8 and 77.7 %, respectively, while the digital DNA–DNA hybridization (dDDH) values between strain WSW3-B6T and the above closely related strains were 21.0, 20.4 and 20.3 %, respectively. Both the ANI and dDDH values supported the creation of a new species in the genus Flavobacterium . The major fatty acids (>10 %) were iso-C15 : 0 (19.3 %), C16 : 0 (14.0 %), iso-C17 : 0 3-OH (13.1 %) and C18 : 0 (10.7 %). The polar lipids of strain WSW3-B6T included phosphatidylethanolamine, three unidentified aminolipids and three unidentified lipids. Moreover, MK-6 was the only respiratory quinone. A comparison of the phylogenetic distinctiveness and the unique phenotypic and chemotaxonomic characteristics among strain WSW3-B6T and closely related type strains supported that strain WSW3-B6T (=KCTC 82708T=GDMCC 1.2627T) represents a novel species of the genus Flavobacterium , for which the name Flavobacterium litorale sp. nov. is proposed.

Flavobacterium phycosphaerae sp. nov. isolated from the phycosphere of Microcystis aeruginosa

A novel aerobic bacterial strain, designated MK012^T, was isolated from the phycosphere of Microcystis aeruginosa. MK012^T appears to be Gram-stain-negative, non-motile and rod-shaped and has yellow pigments. Phylogenetic analysis using 16S rRNA revealed that this bacterium was most closely related to Flavobacterium buctense T7^T (=JCM 30750^T; 97.5 %), Flavobacterium dankookense ARSA-19^T (=KCTC 23179^T; 97.5 %) and Flavobacterium macrobrachii an-8^T (=DSM 22219^T; 97.3 %). The genome size and genomic DNA G+C content of MK012^T were estimated at 3.3 Mbp and 37.6 mol%, respectively. The average nucleotide identity (ANI), average amino acid identity (AAI) and in silico DNA-DNA hybridization (dDDH) values of MK012^T and the members of the genus Flavobacterium were found to be 71.8-78.3 %, 65.1-79.6% and 19.1-21.5 %, respectively. MK012^T exhibited oxidase but no catalase activity. The cells grew at 14-36 °C (optimum, 25 °C), pH 5-10 (optimum, pH 7) and 0-0.4 % (w/v) NaCl (optimum, 0 % NaCl) in R2A medium. MK012^T did not produce flexirubin-type pigments. The predominant cellular fatty acids of MK012^T were determined to be iso-C_15 : 0, iso-C_15 : 0 3-OH, iso-C_17 : 0 3-OH, and summed feature 9 (10-methyl C_16 : 0 and/or iso-C_17 : 1ω9c); MK-6 was identified as its only respiratory quinone. Its major polar lipids were determined to be phosphatidylethanolamine, two unidentified aminolipids, and two unidentified polar lipids. The genotypic and phenotypic characteristics indicate that MK012^T (=KACC 21509^T=JCM 33879^T) represents a novel species of the genus Flavobacterium; therefore, the name Flavobacterium phycosphaerae sp. nov. is proposed.

Flavobacterium salilacus sp. nov., isolated from surface water of a hypersaline lake, and descriptions of Flavobacterium salilacus subsp. altitudinum subsp. nov. and Flavobacterium salilacus subsp. salilacus subsp. nov

Two yellow-pigmented, Gram-stain-negative, aerobic, rod-shaped bacteria were isolated from the water of the hypersaline Chaka Salt Lake (strain SaA2.12^T) and sediment of Qinghai Lake (strain LaA7.5^T), PR China. According to the 16S rRNA phylogeny, the isolates belong to the genus Flavobacterium, showing the highest 16S rRNA sequence similarities to Flavobacterium arcticum SM1502^T(97.6-97.7 %) and Flavobacterium suzhouense XIN-1^T(96.5-96.6 %). Moreover, strains SaA2.12^T and LaA7.5^T showed 99.73 % 16S rRNA sequence similarity to each other. Major fatty acids, respiratory quinones and polar lipids detected in these isolates were iso-C_15 : 0, menaquinone-6 and phosphatidylethanolamine, respectively. Strains SaA2.12^T and LaA7.5^T showed significant unique characteristics between them as well as between the closest phylogenetic members. The highest digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between SaA2.12^T and its closest neighbours were 25.3 and 82.8 %, respectively; whereas these values (highest) between LaA7.5^T and its closest members were 25.2 and 82.8 %, respectively. The dDDH and ANI values between strains SaA2.12^T and LaA7.5^T were calculated as 75.9 and 97.2 %, respectively. Therefore, based on polyphasic data, we propose that strain SaA2.12^T represents a novel species with the name Flavobacterium salilacus sp. nov., with the type strain SaA2.12^T (=KCTC 72220^T=MCCC 1K03618^T) and strain LaA7.5^T as a subspecies within novel Flavobacterium salilacus with the name Flavobacterium salilacus subsp. altitudinum subsp. nov., with the type strain LaA7.5^T (=KCTC 72806^T=MCCC 1K04372^T). These propositions automatically create Flavobacterium salilacus subsp. salilacus subsp. nov. with SaA2.12^T (=KCTC 72220^T=MCCC 1K03618^T) as the type strain.