Search

Endophytes can facilitate the improvement of plant growth and health in agriculturally important crops, yet their genomes and secondary metabolites remain largely unexplored. We previously isolated Saccharibacillus brassicae strain ATSA2T from surface-sterilized seeds of kimchi cabbage and represented a novel species of the genus Saccharibacillus. In this study, we evaluated the plant growth-promoting (PGP) effect of strain ATSA2T in kimchi cabbage, bok choy, and pepper plants grown in soils. We found a significant effect on the shoot and root biomass, and chlorophyll contents following strain ATSA2T treatment. Strain ATSA2T displayed PGP traits such as indole acetic acid (IAA, 62.9 μg/mL) and siderophore production, and phosphate solubilization activity. Furthermore, genome analysis of this strain suggested the presence of gene clusters involved in iron acquisition (fhuABD, afuABC, fbpABC, and fepCDG) and phosphate solubilization (pstABCHS, phoABHLU, and phnCDEP) and other phytohormone biosynthesis genes, including indole-3-acetic acid (trpABCDEFG), in the genome. Interestingly, the secondary metabolites cerecidin, carotenoid, siderophore (staphylobactin), and bacillaene underlying plant growth promotion were found in the whole genome via antiSMASH analysis. Overall, physiological testing and genome analysis data provide comprehensive insights into plant growth-promoting mechanisms, suggesting the relevance of strain ATSA2T in agricultural biotechnology.

Strain KSNA2T, a Gram-negative, moderately halophilic, facultatively anaerobic, motile, rod-shaped bacterium, was isolated from the surface-sterilized stem tissue of a beach morning glory (Cafystegia soldanella) plant in Chuja Island, Jeju-do, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene and whole-genome sequences revealed that strain KSNA2T formed a distinct lineage within the family Enterobacteriaceae, with the highest 16S rRNA gene sequence similarity to Izhakiella australiensis KCTC 72143 (96.2%) and Izhakiella capsodis KCTC 72142T (96.0%), exhibited 95.5-95.9% similarity to other genera in the family Enterobacter-iaceae and Erwiniaceae. Conserved signature indels analysis elucidated that strain KSNA2T was delimited into family Enterobacteriaceae. KSNA2 genome comprises a circular chromosome of 5,182,800 bp with 56.1% G + C content Digital DNA-DNA relatedness levels between strain KSNA2T and 18 closely related species were 19.3 to 21.1%. Average nucleotide identity values were between 72.0 and 76.7%. Growth of strain KSNA2T was observed at 4 to 45°C (optimum, 25°C) and pH 5.0 to 12.0 (optimum, pH 7.0) in the presence of 0 to 11% (w/v) NaCl (optimum, 0-7%). The major cellular fatty acids (> 10%) were C16:o followed by summed feature 8 (C18ω7c and/or C18ω6c), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C17:0cyclo, and C14:0. The major isoprenoid quinone was ubiquinone-8 (Q-8). With combined phylogenetic, genomic, phenotypic, and chemotaxo-nomic features, strain KSNA2T represents a novel species of a new genus in the family Enterobacteriaceae, for which the name Jejubacter calystegiae gen. nov., sp. nov. is proposed. The type strain is KSNA2T (= KCTC 72234T = CCTCC AB 2019098T).

A bacterial strain, designated J12C1-MA-4

A strictly aerobic, motile, endospore-forming, rod-shaped bacterium, designated HS21T, was isolated from rhizospheric soil of the Korean fir tree (Abies koreana) from Halla mountain on Jeju island, Korea. Growth of strain HS21T was observed at pH 6.0-8.0 (optimum: pH 7.0), 0-2% (w/v) NaCl and 4-30°C (optimum: 25°C). A comparative analysis of 16S rRNA gene sequences showed that strain HS21T was most closely related to Cohnella luojiensis HY-22RT (97.6%), followed by C. lupini RLAHU4BT (97.4%) and C. collisoli NKM-5T (97.2%). The genome of strain HS21T comprised a circular chromosome of 7,059,027 bp with 44.8% G + C content. The DNA-DNA relatedness values between strain HS21T and C. luojiensis HY-22RT and C. lupini RLAHU4BT were 18.1% and 13.8%, respectively. The major cellular fatty acids (> 5%) of the isolate were anteiso-C15:0, iso-C16:0, C16:0, and iso-C15:0. The polar lipids present were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, lysylphosphatidylglycerol, and three unidentified aminophospholipids. Based on its phenotypic, phylogenetic, genomic, and chemotaxonomic properties, strain HS21T represents a novel species of the genus Cohnella, for which the name Cohnella abietis sp. nov. is proposed. The type strain is HS21T (= KCTC 43028T = CCTCC AB 2019010T).