Mucilaginibacter hankyongensis sp. nov., isolated from soil of ginseng field Baekdu Mountain

Identification of Mucilaginibacter conchicola sp. nov., Mucilaginibacter achroorhodeus sp. nov. and Mucilaginibacter pallidiroseus sp. nov. and emended description of the genus Mucilaginibacter

Three chitinolytic, Gram-negative, light pink, capsule-forming, rod-shaped bacterial strains with gliding motion (MYSH2T, MJ1aT and dk17T) were isolated from seashells, soil and foxtail, respectively. Phylogenetic analysis of the 16S rRNA gene sequences and concatenated alignment of 92 core genes indicated that strains MYSH2T, MJ1aT and dk17T were novel species of the genus Mucilaginibacter and exhibited a high 16S rRNA sequence similarity (i.e. more than 97.2 %) among each other. These novel strains contained summed feature 3 (C16:1 ω7c and/or C16:1 ω6), iso-C15:0 and MK-7 as the predominant fatty acids and menaquinone. According to the CAZys coding gene of KAAS, MYSH2T and MJ1aT were interpreted as strains containing both GH18 and 19 family coding genes, except for dk17T, which shows only GH19 family genes. These strains likely degrade chitin to chitobiose or directly to N-acetyl-d-glucosamine, which may enhance their chitinolytic capacity, thus making these stains potentially useful for industrial chitin degradation. Based on distinct morphological, physiological, chemotaxonomic and phylogenetic differences from their closest phylogenetic neighbours, we propose that strains MYSH2T, MJ1aT and dk17T represent three novel species in the genus Mucilaginibacter , for which the names Mucilaginibacter conchicola sp. nov. (=KACC 19716T=JCM 32787T), Mucilaginibacter achroorhodeus sp. nov. (=KACC 19906T=NBRC 113667T) and Mucilaginibacter pallidiroseus sp. nov. (=KACC 19907T=NBRC 113666T) are proposed. An emended description of the genus Mucilaginibacter is proposed.

Mucilaginibacter hurinus sp. nov., isolated from briquette warehouse soil

A novel bacterial strain, designated ZR32^T, was isolated from briquette warehouse soil in Ulsan (Korea). The strain was aerobic, showing pink-colored colonies on R2A agar. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain ZR32^T was closely related to Mucilaginibacter soli R9-65^T (97.0%), Mucilaginibacter gynuensis YC7003^T (96.9%), and Mucilaginibacter lutimaris BR-3^T (96.8%). The values of DNA-DNA relatedness related two highest strains M. soli R9-65^T and M. gynuensis YC7003^T were 31.2 ± 6.9% and 19.7 ± 0.3%, respectively. Its genome size was 3.9 Mb, comprising 3402 predicted genes. The DNA G+C content of strain ZR32^T was 43.0 mol%. The major cellular fatty acids (> 5% of total) were summed feature 3 (C_16:1ω6c and/or C_16:1ω7c), C_16:0, C_16:1ω5c, iso-C_15:0, iso-C_17:0 3-OH, and C_17:1ω9c. The major respiratory quinine was menaquinone-7 (MK-7). The major polar lipids were phosphatidylethanolamine, two unidentified phospholipids, one unidentified sphingolipid, and one unidentified polar lipid. Strain ZR32^T showed distinctive characteristics such as the temperature and pH for growth ranges, being positive for β-glucosidase, salicin production, negative for N-acetyl-glucosamine assimilation, being resistant to carbenicillin and piperacillin to related species. On the basis of phenotypic, chemotaxonomic, and phylogenetic data, strain ZR32^T represents a novel species of the genus Mucilaginibacter, for which the name Mucilaginibacter hurinus sp. nov. is proposed. The type strain is ZR32^T (= KCTC 62193 = CCTCC AB 2017285).

Genomic Islands Confer Heavy Metal Resistance in Mucilaginibacter kameinonensis and Mucilaginibacter rubeus Isolated from a Gold/Copper Mine

Heavy metals (HMs) are compounds that can be hazardous and impair growth of living organisms. Bacteria have evolved the capability not only to cope with heavy metals but also to detoxify polluted environments. Three heavy metal-resistant strains of Mucilaginibacer rubeus and one of Mucilaginibacter kameinonensis were isolated from the gold/copper Zijin mining site, Longyan, Fujian, China. These strains were shown to exhibit high resistance to heavy metals with minimal inhibitory concentration reaching up to 3.5 mM Cu^(II), 21 mM Zn^(II), 1.2 mM Cd^(II), and 10.0 mM As^(III). Genomes of the four strains were sequenced by Illumina. Sequence analyses revealed the presence of a high abundance of heavy metal resistance (HMR) determinants. One of the strain, M. rubeus P2, carried genes encoding 6 putative P_IB-1-ATPase, 5 putative P_IB-3-ATPase, 4 putative Zn^(II)/Cd^(II) P_IB-4 type ATPase, and 16 putative resistance-nodulation-division (RND)-type metal transporter systems. Moreover, the four genomes contained a high abundance of genes coding for putative metal binding chaperones. Analysis of the close vicinity of these HMR determinants uncovered the presence of clusters of genes potentially associated with mobile genetic elements. These loci included genes coding for tyrosine recombinases (integrases) and subunits of mating pore (type 4 secretion system), respectively allowing integration/excision and conjugative transfer of numerous genomic islands. Further in silico analyses revealed that their genetic organization and gene products resemble the Bacteroides integrative and conjugative element CTnDOT. These results highlight the pivotal role of genomic islands in the acquisition and dissemination of adaptive traits, allowing for rapid adaption of bacteria and colonization of hostile environments.

Terrabacter ginsengisoli sp. nov., isolated from ginseng cultivating soil

A Gram-positive, strictly aerobic, nonmotile, yellowish, coccus-rod-shaped bacterium (designated Gsoil 653^T) isolated from ginseng cultivating soil was characterized using a polyphasic approach to clarify its taxonomic position. The strain Gsoil 653^T exhibited optimal growth at pH 7.0 on R2A agar medium at 30°C. Phylogenetic analysis based on 16S rRNA gene sequence similarities, indicated that Gsoil 653^T belongs to the genus Terrabacter of the family Humibacillus, and was closely related to Terrabacter tumescens DSM 20308^T (98.9%), Terrabacter carboxydivorans PY2^T (98.9%), Terrabacter terrigena ON10^T (98.8%), Terrabacter terrae PPLB^T (98.6%), and Terrabacter lapilli LR-26^T (98.6%). The DNA G + C content was 70.5 mol%. The major quinone was MK-8(H₄). The primary polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidyl-ethanolamine. The predominant fatty acids were iso-C_15:0, iso-C_16:0, iso-C_14:0, and anteiso-C_15:0, as in the case of genus Terrabacter, thereby supporting the categorization of strain Gsoil 653^T. However, the DNA-DNA relatedness between Gsoil 653^T and closely related strains of Terrabacter species was low at less than 31%. Moreover, strain Gsoil 653^T could be both genotypically and phenotypically distinguished from the recognized species of the genus Terrabacter. This isolate, therefore, represents a novel species, for which the name Terrabacter ginsengisoli sp. nov. is proposed with the type strain Gsoil 653^T (= KACC 19444^T = LMG 30325^T).