The GenBank accession number for the 16S rRNA gene sequence of strain K13M18 T is MK285603. The NCBI accession number for the wholegenome sequence of strain K13M18 T is CP034328. †These authors contributed equally to this work Four supplementary figures and two supplementary tables are available with the online version of this article.

Nontuberculous mycobacterial pulmonary diseases (NTM-PDs) are emerging as global health threats with issues of antibiotic resistance. Accumulating evidence suggests that the gut–lung axis may provide novel candidates for host-directed therapeutics against various infectious diseases. However, little is known about the gut–lung axis in the context of host protective immunity to identify new therapeutics for NTM-PDs. This study was performed to identify gut microbes and metabolites capable of conferring pulmonary immunity to NTM-PDs. Using metabolomics analysis of sera from NTM-PD patients and mouse models, we showed that the levels of l -arginine were decreased in sera from NTM-PD patients and NTM-infected mice. Oral administration of l -arginine significantly enhanced pulmonary antimicrobial activities with the expansion of IFN-γ-producing effector T cells and a shift to microbicidal (M1) macrophages in the lungs of NTM-PD model mice. Mice that received fecal microbiota transplants from l -arginine-treated mice showed increased protective host defense in the lungs against NTM-PD, whereas l -arginine-induced pulmonary host defense was attenuated in mice treated with antibiotics. Using 16S rRNA sequencing, we further showed that l -arginine administration resulted in enrichment of the gut microbiota composition with Bifidobacterium species. Notably, oral treatment with either Bifidobacterium pseudolongum or inosine enhanced antimicrobial pulmonary immune defense against NTM infection, even with multidrug-resistant clinical NTM strains. Our findings indicate that l -arginine-induced gut microbiota remodeling with enrichment of B. pseudolongum boosts pulmonary immune defense against NTM infection by driving the protective gut–lung axis in vivo .

A novel coccus-shaped, Gram-stain-positive, non-motile and aerobic bacterium, designated strain NSG39, was isolated from the intestine of a Korean rockfish, Sebastes schlegelii. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the newly isolated strain NSG39 was closely related to Tessaracoccus flavus RP1 (98.0 %). The isolate grew at 15-37 °C, pH 7-9 and 0-4 % (w/v) salinity, with optimal growth at 30 °C, pH 8 and 0 % (w/v) salinity. The cell wall of the organism contained ll-diaminopimelic acid as a diagnostic diamino acid, and ribose, mannose, glucose and galactose as diagnostic sugars. The polar lipid comprised diphosphatidylglycerol, phosphatidylglycerol, three glycolipids and four unidentified polar lipids. The major cellular fatty acid was anteiso-C15 : 0 (47.2 %). The major menaquinone was MK-9 (H4). The DNA G+C content of the isolate was 68.8 mol%. The genome-based orthologous average nucleotide identity value for strain NSG39 and T. flavus RP1 was 76.6 %. Based on the phylogenetic analysis and its biological characteristics, strain NSG39 is considered to represent a novel species of the genus Tessaracoccus, for which the name Tessaracoccus aquimaris is proposed. The type strain is NSG39 (=KACC 17540=JCM 19289).

A novel coccus-shaped, Gram-stain-positive, non-motile and facultative aerobic bacterium, designated strain D7T301T, was isolated from the small intestine of a marten, Martes flavigula, which was killed on the road in Pocheon-si, Gyeonggi-do, Republic of Korea. Grown on a tryptic soy yeast agar plate, colonies had a creamy colour and irregular form. The new isolate formed a monophyletic clade with Vagococcus penaei CD276T on a phylogenetic consensus tree based on the 16S rRNA gene sequence. The isolate grew optimally at 37 °C and pH 7 in the presence of 0.5 % (w/v) NaCl. The isolate was catalase- and oxidase-negative. The cell-wall peptidoglycan was type A4α l-Lys-d-Asp. The major cellular fatty acids were C16 : 0, C14 : 0, and C16 : 1ω9c. The predominant respiratory quinone was menaquinone MK-7 (85.1 %). The DNA G+C content based on genome sequencing was 33.8 mol%. The average nucleotide identity value obtained from comparative genomic analysis between strain D7T301T and V. penaei CIP 109914T was 72.6 %. On the basis of the phenotypic, phylogenetic, biochemical, chemotaxonomic, and genotypic analyses, Vagococcusmartis is proposed as a novel species of the genus Vagococcus. The type strain is D7T301T (=KCTC 21069T=JCM 31178T).

A strictly anaerobic, Gram-stain-positive, non-motile and coccoid- or oval-shaped bacterium, designated strain KB1, was isolated from a faecal sample of a patient with diverticulitis in South Korea. Degeneracies in the 16S rRNA gene sequence of strain KB1 were resolved by cloning, which yielded five different sequences with heterogeneity. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain KB1 formed a monophyletic branch with species in the genus Blautia, with highest sequence similarity to the type strain of Blautia producta (97.7-98.9 %), followed by Blautia coccoides (97.5-98.1 %). Strain KB1 was able to grow at temperatures of between 15 and 42 °C, with optimal growth at 37 °C, and in the presence of 20 % dehydrated bile. Acetic acid, succinic acid, lactic acid and fumaric acid were produced by strain KB1 from Gifu anaerobic medium broth as metabolic fermentation end-products. The major cellular fatty acids of strain KB1 were C14 : 0, C16 : 0 and C16 : 0 dimethyl aldehyde. The DNA G+C content was 46.3 mol%. The average nucleotide identity value between strain KB1 and the type strain of B. producta was 84.1 %. On the basis of polyphasic analysis, strain KB1 represents a novel species in the genus Blautia, for which the name Blautia hominis sp. nov. is proposed. The type strain is KB1 (=KCTC 15618=JCM 32276).

Two strains, VM2412T and VR2415T, were isolated from the feces of an Andean condor (Vultur gryphus) living in Seoul Grand Park, Gyeonggi-do, South Korea. Cells of both strains were observed to be Gram-stain positive, non-motile, aerobic, catalase positive and oxidase negative. Growth was found to occur at 10-30°C, showing optimum growth at 30°C. The strains could tolerate up to 15% (w/v) NaCl concentration and grow at pH 6-9. The strains shared 99.3% 16S rRNA gene sequence similarity to each other but were identified as two distinct species based on 89.0-89.2% ANIb, 90.3% ANIm, 89.7% OrthoANI and 38.0% dDDH values calculated using whole genome sequences. Among species with validly published names, Brachybacterium ginsengisoli DCY80T shared high 16S rRNA gene sequence similarities with strains VM2412T (98.7%) and VR2415T (98.4%) and close genetic relatedness with strains VM2412T (83.3–83.5% ANIb, 87.0% ANIm, 84.3% OrthoANI and 27.8% dDDH) and VR2415T (82.8–83.2% ANIb, 86.7% ANIm, 83.9% OrthoANI and 27.2% dDDH). The major fatty acid of the two strains was identified as anteiso-C15:0 and the polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, presumptively phosphatidylethanolamine and three unidentified glycolipids. Strain VR2415T also produced an unidentified phospholipid. The cell walls of the two strains contained meso-diaminopimelic acid as diagnostic diamino acid and the whole cell sugars were ribose, glucose, and galactose. The strains contained MK-7 as their predominant menaquinone. The genomes of strains VM2412T, VR2415T, and B. ginsengisoli DCY80T were sequenced in this study. The genomic G+C contents of strains VM2412T and VR2415T were determined to be 70.8 and 70.4 mol%, respectively. A genome-based phylogenetic tree constructed using an up-to-date bacterial core gene set (UBCG) showed that the strains formed a clade with members of the genus Brachybacterium, supporting their taxonomic classification into the genus Brachybacterium. Based on phenotypic and genotypic analyses in this study, strains VM2412T and VR2415T are considered to represent two novel species of the genus Brachybacterium and the names Brachybacterium vulturis sp. nov. and Brachybacterium avium sp. nov. are proposed for strains VM2412T (=KCTC 39996T = JCM 32142T) and VR2415T (=KCTC 39997T = JCM 32143T), respectively.

Background Invertebrates are a very attractive subject for studying host-microbe interactions because of their simple gut microbial community and host diversity. Studying the composition of invertebrate gut microbiota and the determining factors is essential for understanding their symbiotic mechanism. Cephalopods are invertebrates that have similar biological properties to vertebrates such as closed circulation system, an advanced nervous system, and a well-differentiated digestive system. However, it is not currently known whether their microbiomes have more in common with vertebrates or invertebrates. This study reports on the microbial composition of six cephalopod species and compares them with other mollusk and marine fish microbiomes to investigate the factors that shape the gut microbiota. Results Each cephalopod gut consisted of a distinct consortium of microbes, with Photobacterium and Mycoplasma identified as core taxa. The gut microbial composition of cephalopod reflected their host phylogeny, the importance of which was supported by a detailed oligotype-level analysis of operational taxonomic units assigned to Photobacterium and Mycoplasma. Photobacterium typically inhabited multiple hosts, whereas Mycoplasma tended to show host-specific colonization. Furthermore, we showed that class Cephalopoda has a distinct gut microbial community from those of other mollusk groups or marine fish. We also showed that the gut microbiota of phylum Mollusca was determined by host phylogeny, habitat, and diet. Conclusion We have provided the first comparative analysis of cephalopod and mollusk gut microbial communities. The gut microbial community of cephalopods is composed of distinctive microbes and is strongly associated with their phylogeny. The Photobacterium and Mycoplasma genera are core taxa within the cephalopod gut microbiota. Collectively, our findings provide evidence that cephalopod and mollusk gut microbiomes reflect host phylogeny, habitat, and diet. It is hoped that these data can contribute to future studies on invertebrate–microbe interactions.

Castration of young males is widely used in the cattle industry to improve meat quality, but the mechanism linking hypogonadism and host metabolism is not clear. Here, we use metataxonomic and metabolomic approaches to evaluate the intestinal microbiota and host metabolism in male, castrated male (CtM), and female cattle. After pubescence, the CtM cattle harbor distinct ileal microbiota dominated by the family Peptostreptococcaceae and exhibit distinct serum and muscle amino acid profiles (i.e., highly abundant branched-chain amino acids), with increased extra-and intramuscular fat storage. We also evaluate the causative factor(s) that underpin the alteration of the intestinal microbiota and host metabolic phenotype in response to hypogonadism. Castration of male mice phenocopies both the intestinal microbial alterations and obese-prone metabolism observed in cattle. Antibiotic treatment and fecal microbiota transplantation experiments in a mouse model confirm that the intestinal microbial alterations associated with hypogonadism are a key contributor to the obese phenotype in the CtM animals. Collectively, targeting the gut microbiota is a potential therapeutic strategy for the treatment of both hypogonadism and obesity.