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

Microbacterium humicola sp. nov., Microbacterium terrisoli sp. nov., Paenibacillus pedocola sp. nov., Paenibacillus silviterrae sp. nov., Flavobacterium terrisoli sp. nov., and Aquabacterium humicola sp. nov., isolated from soil

Four Gram-stain-positive and two Gram-stain-negative bacterial strains, designated as W4T, FW7T, TW48T, UW52T, PT-3T, and RJY3T, were isolated from soil samples collected from the Republic of Korea. The 16S rRNA gene sequence analysis showed that strains W4T and FW7T belonged to the genus Microbacterium, strains TW48T and UW52T were affiliated to the genus Paenibacillus, strain PT-3T was related to the genus Flavobacterium, and strain RJY3T was associated with the genus Aquabacterium. The closest phylogenetic taxa to W4T, FW7T, TW48T, UW52T, PT-3T, and RJY3T were Microbacterium bovistercoris NEAU-LLET (97.7 %), Microbacterium protaetiae DFW100M-13T (97.9 %), Paenibacillus auburnensis JJ-7T (99.6 %), Paenibacillus allorhizosphaerae JJ-447T (95.7 %), Flavobacterium buctense T7T (97.1 %), and Aquabacterium terrae S2T (99.5 %), respectively. Average nucleotide identity and digital DNA-DNA hybridization values between the novel strains and related reference type strains were <95.0 % and <70.0 %, respectively. The major cellular fatty acid in strains W4T, FW7T TW48T, and UW52T was antiso-C15 : 0. Similarly, strain PT-3T revealed iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, and iso-C15 : 0 3-OH as its principal fatty acids. On the other hand, RJY3T exhibited summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c), C16 : 0, summed feature 8 (C18 : 1  ω7c and/or C18 : 1  ω6c), and C12 : 0 as its predominant fatty acids. Overall, the polyphasic taxonomic data indicated that strains W4T, FW7T, TW48T, UW52T, PT-3T, and RJY3T represent novel species within the genera Microbacterium, Paenibacillus, Flavobacterium, and Aquabacterium. Accordingly, we propose the names Microbacterium humicola sp. nov., with the type strain W4T (=KCTC 49888T=NBRC 116001T), Microbacterium terrisoli sp. nov., with the type strain FW7T (=KCTC 49859T=NBRC 116000T), Paenibacillus pedocola sp. nov., with the type strain TW48T (=KCTC 43470T=NBRC 116017T), Paenibacillus silviterrae sp. nov., with the type strain UW52T (=KCTC 43477T=NBRC 116018T), Flavobacterium terrisoli sp. nov., with the type strain PT-3T (=KCTC 92106T=NBRC 116012T), and Aquabacterium humicola sp. nov., with the type strain RJY3T (=KCTC 92105T=NBRC 115831T).

Rhizorhabdus phycosphaerae sp. nov., isolated from the phycosphere of Microcystis aeruginosa

A novel bacterial strain, designated MK52T, was isolated from the phycosphere of Microcystis aeruginosa . Strain MK52T is a Gram-stain-negative, pink-pigmented, rod-shaped, strictly aerobic bacterium. In 16S rRNA phylogenetic analysis, the MK52T strain was most closely related to Rhizorhabdus wittichii RW1T (98.66 %) and Rhizorhabdus histidinilytica UM2T (98.51 %). The genomic DNA G+C content of strain MK52T was calculated to be 65.5 mol%. The average nucleotide identity values of strain MK52T with R. wittichii RW1T and R. histidinilytica UM2T were 80.35 and 80.23 %, respectively, with digital DNA–DNA hybridization values of 23.6 and 22.9 %, respectively, and average amino acid identities of 75.59 and 75.79 %, respectively. The major isoprenoid quinone was Q-10, and the predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and sphingoglycolipid. Fatty acid methyl ether analysis showed that summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) was the main cellular fatty acid in strain MK52T. Strain MK52T cells grew at 21–34 °C (optimum, 30 °C), pH 5–8 (optimum, pH 7) and with 0–2 % (w/v) NaCl (optimum, 0.5 % NaCl). Rhizorhabdus phycosphaerae sp. nov. is proposed as a new species (=KCTC 72877T=DSM 111424T) based on its genotypic and phenotypic characteristics.