Paraburkholderia translucens sp. nov. and Paraburkholderia sejongensis sp. nov., isolated from grassland soil and showing plant growth promoting potential.

Two Gram-negative bacterial strains designated MMS20-SJTN17T and MMS20-SJTR3T were isolated from a grassland soil sample, and taxonomically characterized using a polyphasic approach. The 16S rRNA gene sequence analysis indicates that both strains belong to the genus Paraburkholderia of the class Betaproteobacteria, with strain MMS20-SJTN17T being mostly related to Paraburkholderia sprentiae WSM5005T (96.45 % sequence similarity) and strain MMS20-SJTR3T to Paraburkholderia tuberum STM678T (98.59 % sequence similarity). MMS20-SJTN17T could grow at 15-40 °C (optimum, 25-30 °C) and at pH 6.0-8.0 (optimum, pH 6.0-7.0), whereas MMS20-SJTR3T could grow at 10-40 °C (optimum, 30-37 °C) and at pH 6.0-8.0 (optimum, pH 6.0). Both strains tolerated up to 1 % (w/v) NaCl (optimum, 0 %). The major fatty acids of MMS20-SJTN17T were C16 : 0 and C19 : 0 cyclo ω8c, and those of MMS20-SJTR3T were C17 : 0 cyclo and a summed feature comprising C18 : 1 ω7c and/or C18 : 1 ω6c. The major isoprenoid quinone of both strains was ubiquinone-8 and the diagnostic polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Regarding plant growth promoting potential, both strains were capable of producing indole acetic acid, siderophore and 1-aminocyclopropane-1-carboxylic acid deaminase, and also showed phosphate-solubilizing activity. A genome-based comparison using orthologous average nucleotide identity and digital DNA-DNA hybridization values indicates that strain MMS20-SJTN17T shares highest relatedness with Paraburkholderia monticola JC2948T and MMS20-SJTR3T with Paraburkholderia antibiotica G-4-1-8T, with values clearly below the cutoffs for species distinction. Examination of biosynthetic gene clusters responsible for secondary metabolite production reveals unique characteristics distinguishing each strain from closely related Paraburkholderia species. On the basis of genotypic, phenotypic, chemotaxonomic and phylogenomic data, each strain should be classified as a novel species of the genus Paraburkholderia, for which the names Paraburkholderia translucens sp. nov. (=MMS20-SJTN17T=LMG 32366T=KCTC 82783T) and Paraburkholderia sejongensis sp. nov. (=MMS20-SJTR3T=LMG 32367T=KCTC 82784T) are proposed.

Flavobacterium humidisoli sp. nov., isolated from riverside soil.

A novel Gram-stain-negative, yellow-pigmented, non-motile and rod-shaped bacterial strain designated MMS21-Er5T was isolated and subjected to polyphasic taxonomic characterization. MMS21- Er5T could grow at 4-34 °C (optimum, 30 °C), at pH 6-8 (optimum, pH 7) and in the presence of 0-2% NaCl (optimum, 1 %). The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that MMS21- Er5T showed low levels of sequence similarities with other species, as the highest similarity of 97.83 % was observed with Flavobacterium tyrosinilyticum THG DN8.8T, then 97.68 % with 'Flavobacterium ginsengiterrae' DCY 55 and 97.63 % with Flavobacterium banpakuense 15F3T, which were well below the suggested cutoff for species distinction. The whole genome sequence of MMS21-Er5T consisted of a single contig of 5.63 Mbp, and the DNA G+C content was 34.06 mol%. The in-silico DNA-DNA hybridization and orthologous average nucleotide identity values were highest with Flavobacterium tyrosinilyticum KCTC 42726T (45.7 and 91.92% respectively). The predominant respiratory quinone for the strain was menaquinone-6 (MK-6), the major cellular fatty acid was iso-C15 : 0, and the diagnostic polar lipids were phosphatidylethanolamine and phosphatidyldiethanolamine. The combination of physiological and biochemical tests clearly distinguished the strain from related species of the genus Flavobacterium. On the basis of these results, strain MMS21-Er5T evidently represents a novel species of the genus Flavobacterium, for which the name Flavobacterium humidisoli sp. nov. is proposed (type strain=MMS21-Er5T=KCTC 92256T =LMG 32524T).

Brevibacillus humidisoli sp. nov., a moderately thermoalkaliphilic and halotolerant species isolated from riverside soil.

A Gram-stain-positive, aerobic, rod-shaped, motile, and endospore-forming bacterial strain designated MMS20-4M-10-YT was isolated from riverside soil and subjected to taxonomic characterization. Strain MMS20-4M-10-YT was moderately thermophilic, alkaliphilic and halotolerant, as the strain grew at 25-50 °C (optimum, 45 °C), at pH 7.0-10.0 (optimum, pH 8.0) and in the presence of 0-6 % NaCl (optimum, 0 %). Analysis of 16S rRNA gene sequences indicated that MMS20-4M-10-YT fell into a phylogenetic cluster belonging to the genus Brevibacillus. Strain MMS20-4M-10-YT showed the highest 16S rRNA gene sequence similarity to Brevibacillus marinus SCSIO 07484T (96.7 %). Based on the reults of orthologous average nucleotide identity analysis, MMS20-4M-10-YT was again mostly related to B. marinus SCSIO 07484T with 78.0 % identity, which also shared the highest average nucleotide identity of 68.0 %. In contrast, the digital DNA-DNA relatedness analysis indicated that Aneureibacillus migulanus DSM 2895T was the closest species with 29.5 % similarity. The genome-based analyses indicated that all compared species showed low genomic relatedness with MMS20-4M-10-YT. The major fatty acids of the strain were anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 0 and iso-C17 : 0, the major respiratory quinone was MK-7, the diagnostic polar lipids were phosphatidyl-N-methylethanolamine, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol, and diagnostic cell-wall diamino acid was meso-diaminopimelic acid, which was consistent with the general chemotaxonomic features of the genus. The total length of the genome was 4.91 Mbp and the DNA G+C content was 51.8 mol%. Based on both phenotypic and phylogenetic evidence, strain MMS20-4M-10-YT should be classified as representing a novel species of the genus Brevibacillus, for which a name Brevibacillus humidisoli sp. nov. (type strain=MMS20-4M-10-YT=KCTC 43333T=LMG 32359T) is proposed.

Micromonospora antibiotica sp. nov. and Micromonospora humidisoli sp. nov., two new actinobacterial species exhibiting antimicrobial potential.

Two novel actinobacterial strains, designated MMS20-R2-23T and MMS20-R2-29T, were isolated from riverside soil and subjected to taxonomic characterization. Both strains were Gram-stain-positive, aerobic, non-motile and filamentous, and formed orange to strong orange-brown coloured colonies, which later turned black. Both strains grew optimally at mesophilic temperatures, neutral to slightly alkaline pH and in the absence of NaCl. Analysis of 16S rRNA gene sequences indicated that the two novel strains fell into phylogenetic clusters belonging to the genus Micromonospora. Strains MMS20-R2-23T and MMS20-R2-29T showed the highest 16S rRNA gene sequence similarity to Micromonospora phytophila SG15T (99.3 %) and Micromonospora humida MMS20-R1-14T (99.4 %), respectively. Based on the comparative genome analysis, strain MMS20-R2-23T had the highest orthologous average nucleotide identity (orthoANI) value of 92.70 % with Micromonospora matsumotoense DSM 44100T, and MMS20-R2-29T shared 94.99 % with Micromonospora wenchangensis CCTCC AA 2012002T. Besides, the digital DNA-DNA hybridization (dDDH) values of MMS20-R2-23T and MMS20-R2-29T with the same species were 47.6 and 59.2% respectively, which were also highest among the compared species, thus confirming the separation of each strain at species level from related species. The orthoANI and dDDH values between MMS20-R2-23T and MMS20-R2-29T were 92.18 and 44.9% respectively. The genomes of strains MMS20-R2-23T and MMS20-R2-29T were estimated as 7.56 Mbp and 7.13 Mbp in size, and the DNA G+C contents were 72.5 and 72.9 mol%, respectively. The chemotaxonomic properties of both strains were consistent with those of the genus. The novel strains showed antimicrobial activity against a broad range of microbes, in particular Gram-positive bacteria and yeasts. It is evident that each of the isolated strains merits recognition as representing novel species of Micromonospora, for which the names Micromonospora antibiotica sp. nov. (type strain=MMS20-R2-23T=KCTC 49542T=JCM 34495T) and Micromonospora humidisoli sp. nov. (type strain=MMS20-R2-29T=KCTC 49543T=JCM 34496T) are proposed.

Micromonospora humida sp. nov., exhibiting antimicrobial potential, isolated from riverside soil.

An actinobacterial strain designated MMS20-R1-14T was isolated from a riverside soil sample. Colonies on agar plates were orange to strong orange brown in colour, which later became black. The cells grew at 10-40 °C (optimum, 37 °C), pH 5.0-11.0 (pH 8.0) and in the presence of 0-4 % NaCl (1 %). The 16S rRNA gene sequence of strain MMS20-R1-14T showed highest similarities to Micromonospora wenchangensis CCTCC AA 2012002T (99.51 %) and Micromonospora rifamycinica AM105T (99.37 %). The orthoANI values between strain MMS20-R1-14T and the two type strains were 95.72 and 90.99 %, and the digital DNA-DNA hybridization values were 63.6 and 40.8 %, respectively, thus confirming the distinction of strain MMS20-R1-14T from its mostly related species. The DNA G+C content of strain MMS20-R1-14T was 72.9 mol%. The strain contained meso-diaminopimelic acid as the major cell-wall amino acid, and the characteristic whole-cell sugars were arabinose, xylose, glucose, ribose and rhamnose. The main cellular fatty acids were C18 : 1 ω9c, iso-C15 : 0 and iso-C16 : 0, the diagnostic polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, and the predominant menaquinones were MK-10(H4) and MK-10(H6), all of which were consistent with those of Micromonospora. Strain MMS20-R1-14T showed antimicrobial activity against a range of bacterial and yeast species. The genome of the strain was found to contain 33 potential biosynthetic gene clusters for secondary metabolites, thus showing a high potential as a producer of bioactive compounds. On the basis of these phenotypic, genotypic and chemotaxonomic data, strain MMS20-R1-14T merits recognition as representing a novel species of the genus Micromonospora, for which the name Micromonospora humida sp. nov. (type strain=MMS20 R1-14T=KCTC 49541T=JCM 34494T) is proposed.