Saxibacter everestensis gen. nov., sp. nov., A Novel Member of the Family Brevibacteriaceae, Isolated from the North Slope of Mount Everest

We isolated and analyzed a novel, Gram-stain-positive, aerobic, rod-shaped, non-motile actinobacterium, designated as strain ZFBP1038T, from rock sampled on the north slope of Mount Everest. The growth requirements of this strain were 10-37 °C, pH 4-10, and 0-6% (w/v) NaCl. The sole respiratory quinone was MK-9, and the major fatty acids were anteiso-C15:0 and iso-C17:0. Peptidoglycan containing meso-diaminopimelic acid, ribose, and glucose were the major cell wall sugars, while polar lipids included diphosphatidyl glycerol, phosphatidyl glycerol, an unidentified phospholipid, and an unidentified glycolipid. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZFBP1038T has the highest similarity with Spelaeicoccus albus DSM 26341 T (96.02%). ZFBP1038T formed a distinct monophyletic clade within the family Brevibacteriaceae and was distantly related to the genus Spelaeicoccus. The G + C content of strain ZFBP1038T was 63.65 mol% and the genome size was 4.05 Mb. Digital DNA-DNA hybridization, average nucleotide identity, and average amino acid identity values between the genomes of strain ZFBP1038T and representative reference strains were 19.3-25.2, 68.0-71.0, and 52.8-60.1%, respectively. Phylogenetic, phenotypic, and chemotaxonomic characteristics as well as comparative genome analyses suggested that strain ZFBP1038T represents a novel species of a new genus, for which the name Saxibacter gen. nov., sp. nov. was assigned with the type strain Saxibacter everestensis ZFBP1038T (= EE 014 T = GDMCC 1.3024 T = JCM 35335 T).

Identification, characterization, and genome sequencing of Brevibacterium sediminis MG-1 isolate with growth-promoting properties

In recent years, plant growth-promoting rhizobacteria (PGPR) have received increased attention due to their prospective use as biofertilizers for the enhancement of crop growth and yields. However, there is a growing need to identify new PGPR isolates with additional beneficial properties. In this paper, we describe the identification of a new strain of a non-sporulating Gram-positive bacterium isolated from the rhizosphere of potato plants, classified as Brevibacterium sediminis MG-1 based on whole-genome sequencing. The bacteria are aerobic; they grow in a pH range of 6.0-10.0 (optimum 6.0), and a temperature range of 20-37 °C (optimum 30 °C). At 96 h of cultivation, strain MG-1 synthesizes 28.65 µg/ml of indole-3-acetic acid (IAA) when 500 µg/ml of l-tryptophan is added. It is a producer of catechol-type siderophores and ACC deaminase (213 ± 12.34 ng/ml) and shows halotolerance. Treatment of pea, rye, and wheat seeds with a suspension of MG-1 strain cells resulted in the stimulation of stem and root biomass accumulation by 12-26% and 6-25% (P < 0.05), respectively. Treatment of seeds with bacteria in the presence of high salt concentration reduced the negative effects of salt stress on plant growth by 18-50%. The hypothetical gene lin, encoding the bacteriocin Linocin-M18, RIPP-like proteins, and polyketide synthase type III (T3PKS) loci, gene clusters responsible for iron acquisition and metabolism of siderophores, as well as gene clusters responsible for auxin biosynthesis, were identified in the B. sediminis MG-1 genome. Thus, the rhizosphere-associated strain B. sediminis MG-1 has growth-stimulating properties and can be useful for the treatment of plants grown on soils with high salinity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03392-z.

Brevibacterium rongguiense sp. nov., isolated from freshwater sediment

A Gram stain-positive, non-spore-forming, non-motile and rod-shaped actinomycete, strain 5221^T, was isolated from the sediment of a river collected at Ronggui in the Pearl River Delta, PR China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain formed a distinct lineage within the genus Brevibacterium and had the highest sequence similarity to Brevibacterium pityocampae Tp12^T (96.7 %), followed by Brevibacterium daeguense 2C6-41^T (96.5 %), Brevibacterium samyangense SST-8^T (96.0 %) and Brevibacterium ravenspurgense 20^T (95.9 %). The results of chemotaxonomic analyses, including detecting anteiso-C_15 : 0, anteiso-C_17 : 0, and C_16 : 0 as the major cellular fatty acids, diphosphatidylglycerol, phosphatidylglycerol and three phosphoglycolipids as the polar lipids, MK-8(H₂) as the major menaquinone, and a DNA G+C content of 72.4 mol%, supported that strain 5221^T is a member of the genus Brevibacterium. Furthermore, low sequence similarities of 16S rRNA gene sequences, differences in fatty acid compositions and differential physiological characteristics such as enzyme activity and carbon sources utilization ability distinguished the isolate from its close relatives. Therefore, strain 5221^T represents a novel species of the genus Brevibacterium, for which the name Brevibacterium rongguiense sp. nov. is proposed, with the type strain 5221^T (=GDMCC 1.1766^T=KACC 21700^T).

Sediminivirga luteola gen. nov., sp. nov., a member of the family Brevibacteriaceae, isolated from marine sediment

A Gram-stain-positive actinobacterial strain, designated F23^T, was isolated from marine sediment collected from the western Pacific. Strain F23^T showed less than 94.5 % 16S rRNA gene sequence similarity with type strains of species with validly published names. Phylogenetic analysis, based on 16S rRNA gene sequences, revealed that the novel isolate formed a distinct monophyletic clade within the family Brevibacteriaceae and clustered distantly with the genera Brevibacterium and Spelaeicoccus. Cells of strain F23^T were non-motile, rod-shaped and aerobic to microaerophilic. Optimal growth occurred at 35-37 °C, at pH 8.0-9.0 and in the presence of 1 % NaCl (w/v). The isolate contained meso-diaminopimelic acid as the characteristic cell-wall diamino acid, MK-8(H₂) and MK-7(H₂) as the predominant menaquinones and anteiso-C_15 : 0 and anteiso-C_17 : 0 as the major fatty acids. The DNA G+C content of strain F23^T was 69.0 mol%. On the basis of phylogenetic analysis, phenotypic and chemotaxonomic characteristics and 16S rRNA gene signature nucleotide patterns, strain F23^T represents a novel species in a novel genus in the family Brevibacteriaceae, for which the name Sediminivirga luteola gen. nov., sp. nov. is proposed. The type strain is F23^T ( = JCM 19771^T = CGMCC 1.12785^T = MCCC 1A09945^T).

Brevibacterium jeotgali sp. nov., isolated from jeotgal, a traditional Korean fermented seafood

A Gram-staining-positive, aerobic, non-motile bacterium, designated strain SJ5-8T, was isolated from seau-jeot (shrimp jeotgal), a traditional fermented seafood in South Korea. Cells were non-spore-forming rods showing catalase- and oxidase-positive reactions. Growth of strain SJ5-8T was observed at 10–37 °C (optimum, 30 °C), at pH 6.0–9.0 (optimum, pH 7.5–8.5) and in the presence of 0–14 % (w/v) NaCl (optimum, 5 %). Phylogenetic inference based on 16S rRNA gene sequences showed that the strain formed a tight phyletic lineage with members of the genus Brevibacterium . Strain SJ5-8T was most closely related to Brevibacterium yomogidense MN-6-aT, Brevibacterium daeguense 2C6-41T and Brevibacterium salitolerans TRM 415T with similarities of 98.9, 97.5 and 97.4 %, respectively. The DNA–DNA relatedness values between strain SJ5-8T and the type strains of B. yomogidense , B. daeguense and B. salitolerans were 51.7±1.9 %, 22.2±4.0 % and 52.4±3.8 %, respectively. Chemotaxonomic data (major sole isoprenoid quinone, MK-8(H2); major diagnostic diamino acid, meso-diaminopimelic acid; major polyamines, putrescine and cadaverine; major cellular fatty acids, anteiso-C15:0, iso-C15:0 and anteiso-C17:0; major polar lipids, phosphatidylglycerol and diphosphatidylglycerol; DNA G+C content, 69.3 mol%) also supported the affiliation of strain SJ5-8T to the genus Brevibacterium . Therefore, strain SJ5-8T represents a novel species of the genus Brevibacterium , for which the name Brevibacterium jeotgali sp. nov. is proposed. The type strain is SJ5-8T ( = KACC 16911T = JCM 18571T).