Massilia litorea sp. nov., Marinobacter salinisoli sp. nov. and Rhodobacter xanthinilyticus sp. nov., isolated from coastal environments.

Three bacterial strains, namely LPB0304T, LPB0319T and LPB0142T, were isolated from coastal environments. The 16S rRNA gene sequences of the three isolates were found to show the highest sequence similarities to Massilia litorea (98.44 %), Marinobacter salinisoli (97.55 %) and Rhodobacter lacus (97.60 %), respectively. The low (<98.7 %) sequence similarities and tree topologies implied the novelty of the three isolates, representing novel genomic species of the genus Massilia, Marinobacter and Rhodobacter. Numerous biochemical and physiological features also supported the distinctiveness of the isolates from previously known species. Based on the phenotypic and phylogenetic data presented in this study, three novel species are suggested with the following names: Massilia litorea sp. nov. (LPB0304T=KACC 21523T=ATCC TSD-216T), Marinobacter salinisoli sp. nov. (LPB0319T=KACC 21522T=ATCC TSD-218T) and Rhodobacter xanthinilyticus sp. nov. (LPB0142T=KACC 18892T=JCM 31567T).

Subspecies-level genome comparison of Lactobacillus delbrueckii.

Lactobacillus delbrueckii comprises six subspecies, L. delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, L. delbrueckii subsp. jakobsenii, L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. sunkii, and L. delbrueckii subsp. indicus. We investigated the evolution of the six subspecies of L. delbrueckii using comparative genomics. While the defining feature of the species was the gene number increment driven by mobile elements and gene fragmentation, the repertoire of subspecies-specific gene gains and losses differed among the six subspecies. The horizontal gene transfer analyses indicated that frequent gene transfers between different subspecies had occurred when the six subspecies first diverged from the common ancestor, but recent gene exchange was confined to a subspecies implying independent evolution of the six subspecies. The subspecies bulgaricus is a homogeneous group that diverged from the other subspecies a long time ago and underwent convergent evolution. The subspecies lactis, jakobsenii, delbrueckii, and sunkii were more closely related to each other than to other subspecies. The four subspecies commonly show increasing genetic variability with increasing genome size. However, the four subspecies were distinguished by specific gene contents. The subspecies indicus forms a branch distant from the other subspecies and shows an independent evolutionary trend. These results could explain the differences in the habitat and nutritional requirements of the subspecies of L. delbrueckii.

Peripheral blood transcriptomic clusters uncovered immune phenotypes of asthma.

BACKGROUND: Transcriptomic analysis has been used to elucidate the complex pathogenesis of heterogeneous disease and may also contribute to identify potential therapeutic targets by delineating the hub genes. This study aimed to investigate whether blood transcriptomic clustering can distinguish clinical and immune phenotypes of asthmatics, and microbiome in asthmatics. METHODS: Transcriptomic expression of peripheral blood mononuclear cells (PBMCs) from 47 asthmatics and 21 non-asthmatics was measured using RNA sequencing. A hierarchical clustering algorithm was used to classify asthmatics. Differentially expressed genes, clinical phenotypes, immune phenotypes, and microbiome of each transcriptomic cluster were assessed. RESULTS: In asthmatics, three distinct transcriptomic clusters with numerously different transcriptomic expressions were identified. The proportion of severe asthmatics was highest in cluster 3 as 73.3%, followed by cluster 2 (45.5%) and cluster 1 (28.6%). While cluster 1 represented clinically non-severe T2 asthma, cluster 3 tended to include severe non-T2 asthma. Cluster 2 had features of both T2 and non-T2 asthmatics characterized by the highest serum IgE level and neutrophil-dominant sputum cell population. Compared to non-asthmatics, cluster 1 showed higher CCL23 and IL1RL1 expression while the expression of TREML4 was suppressed in cluster 3. CTSD and ALDH2 showed a significant positive linear relationship across three clusters in the order of cluster 1 to 3. No significant differences in the diversities of lung and gut microbiomes were observed among transcriptomic clusters of asthmatics and non-asthmatics. However, our study has limitations in that small sample size data were analyzed with unmeasured confounding factors and causal relationships or function pathways were not verified. CONCLUSIONS: Genetic clustering based on the blood transcriptome may provide novel immunological insight, which can be biomarkers of asthma immune phenotypes. Trial registration Retrospectively registered.

Effect of luxS encoding a synthase of quorum-sensing signal molecule AI-2 of Vibrio vulnificus on mouse gut microbiome.

Autoinducer-2 (AI-2), a quorum-sensing signal molecule from the human pathogen Vibrio vulnificus, was assessed for its effect on the gut microbiome of mice. For this, we employed 16S rRNA sequencing to compare the gut microbiome of mice infected with either wild-type V. vulnificus or with the isotype ΔluxS that has a deletion in luxS which encodes the biosynthetic function of AI-2. The relative ratio of wild-type Vibrio species in the jejunum and ileum of mice infected with the wild type was significantly higher than that in mice infected with ΔluxS, suggesting that AI-2 plays an important role in the colonization of V. vulnificus in the small intestine. The bacterial composition in the gut of mice infected with ΔluxS comprises a higher proportion of Firmicutes, composed mainly of Lactobacillus, compared to the mice infected with wild-type cells. In the large intestine, Vibrio species were barely detected regardless of genetic background. Three Lactobacillus spp. isolated from fecal samples from mice infected with ΔluxS manifested significant antibacterial activities against V. vulnificus. Culture supernatants from these three species were dissolved by HPLC, and a substance in fractions showing inhibitory activity against V. vulnificus was determined to be lactic acid. Our results suggest that luxS in V. vulnificus affects not only the ability of the species to colonize the host gut but also its susceptibility to the growth-inhibiting activity of commensal bacteria including Lactobacillus. KEY POINTS: • Gut microbiomes of ΔluxS-infected and WT Vibrio-infected mice differed greatly. • Difference was most prominent in the jejunum and ileum compared to the duodenum or large intestine. • In the small and large intestines of mice, the relative proportions of Vibrio and Lactobacillus species showed a negative relationship. • Effector molecules produced by Lactobacillus in mouse gut inhibit Vibrio growth.

Association of obstructive sleep apnea severity with the composition of the upper airway microbiome.

STUDY OBJECTIVES: Although the airway mucosal system plays a pivotal role in the pathogenesis of obstructive sleep apnea (OSA), the underlying disease mechanism remains unclear. The microbiome greatly impacts human health and disease, particularly in the mucosa, where it can have direct interactions. In this study, we aimed to analyze the microbiome composition in the upper airway mucosa of individuals with and without OSA to identify potential disease severity-related microbial signatures. METHODS: This population-based cohort study involved 92 participants (mean age = 62.7 ± 5.8 years; male-to-female ratio = 0.74) who underwent a physical examination and sleep study. Upper airway swab samples were collected from the nasopharyngeal mucosa to evaluate the microbiome based on 16S rRNA gene pyrosequencing. The relationship between microbiome composition and sleep parameters was explored through bioinformatics analysis. RESULTS: The average apnea-hypopnea index was 7.75 ± 6.5 events/h. Proteobacteria, Firmicutes, and Actinobacteria were the predominant phyla in the nasopharyngeal microbiota in all participants. Simpson diversity indexes were higher in patients with OSA (0.6435 ± 0.2827) than in the control patients (0.6095 ± 0.2683); however, the difference was not significant (P = .1155). Specific anaerobes negatively correlated with the lowest oxygen saturation level during sleep (sum of powered score (1) = -117.47; P = .0052). CONCLUSIONS: The upper airway microbiome of older patients with mild-moderate OSA exhibited minor differences in composition compared with that of individuals without OSA, possibly owing to environmental changes in the upper airway mucosa resulting from recurrent airway obstruction and intermittent hypoxia in patients with OSA. CITATION: Hong S-N, Kim KJ, Baek M-G, et al. Association of obstructive sleep apnea severity with the composition of the upper airway microbiome. J Clin Sleep Med. 2022;18(2):505-515.

Distribution of bacteriocin genes in the lineages of Lactiplantibacillus plantarum.

Lactiplantibacillus plantarum, previously named "Lactobacillus plantarum," is found in a wide variety of environments exhibiting a high level of intraspecies genetic diversity. To investigate the strain diversity, we performed comparative genomic analyses of the 54 complete genome sequences. The results revealed that L. plantarum subsp. plantarum was split into three lineages, A, B and C. Of the genes beneficial for probiotic activity, only those associated with the biosynthesis of plantaricin (Pln), an L. plantarum-specific bacteriocin, were found to be significantly different among the lineages. The genes related to the biosynthesis of plnE/F were conserved throughout the three lineages, whereas the outgroups did not possess any Pln-producing genes. In lineage C, the deepest and ancestral type branch, plnE/F genes, were well conserved. In lineage B, loss of gene function was observed due to mobile elements in the pln loci. In lineage A, most strains were predicted to produce more than one type of Pln by possessing diverse Pln-encoding genes. These results showed the presence of functional diversity arising from the trifurcating evolution in L. plantarum subsp. plantarum and demonstrated that Pln is an indicator for differentiating the three lineages.

Modulation of the Gut Microbiota by Sihocheonggan-Tang Shapes the Immune Responses of Atopic Dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by complex immune dysregulation and closely related to the gut microbiome. The present study investigated the microbiome-mediated effect of Sihocheonggan-Tang (SHCGT) on AD-like symptoms induced by 2,4-dinitrochlorobenzene (DNCB) in BALB/c mice. DNCB was applied regularly to the ear and dorsal skin of BALB/c mice, and SHCGT was administered orally daily for 2 weeks. The composition of the gut microbiota was analyzed using 16S rRNA sequencing, and the effect of gut microbiome-derived metabolites, specifically short-chain fatty acids (SCFAs), was evaluated in tumor necrosis factor-alpha (TNF-α)- and interferon-gamma (IFN-γ)-treated HaCaT cells. SHCGT alleviated DNCB-induced symptoms of AD and the immune response to AD by decreasing the plasma immunoglobulin E level and splenic interleukin-4, interleukin-10, TNF-α, and IFN-γ levels. The gut microbiome composition and the damaged gut epithelial barrier in mice with AD were also significantly altered by SHCGT, and the reduced SCFA levels therein were elevated. We found that SFCAs directly inhibited the mRNA expression of IL-6 and ICAM-1 in TNF-α- and INF-γ-treated HaCaT cells. The finding that SHCGT regulates the gut microbiome and improves DNCB-induced AD in mice suggests that this herbal medicine has therapeutic potential in patients with AD.

VicPred: A Vibrio cholerae Genotype Prediction Tool.

Genomic information can be used to predict major pathogenic traits of pathogens without the need for laboratory experimentation. However, no Vibrio cholerae genome-based trait identification tools currently exist. The aim of this study was to develop a web-based prediction tool to identify Vibrio pathogenic traits using publicly available 796 whole-genome sequences of V. cholerae. Using this application, 68 structural O-antigen gene clusters belonging to 49 serogroups of V. cholerae were classified, and the composition of the genes within the O-antigen cluster of each serogroup was identified. The arrangement and location of the CTX prophage and related elements of the seventh cholera pandemic strains were also revealed. With the versatile tool, named VicPred, we analyzed the assemblage of various SXTs (sulfamethoxazole/trimethoprim resistance element) and major genomic islands (GIs) of V. cholerae, and the increasing trend in drug-resistance revealing high resistance of the V. cholerae strains to certain antibiotics. The pathogenic traits of newly sequenced V. cholerae strains could be analyzed based on these characteristics. The accumulation of further genome data will expedite the establishment of a more precise genome-based pathogenic traits analysis tool.

Interactions between NCR+ILC3s and the Microbiome in the Airways Shape Asthma Severity.

Asthma is a heterogeneous disease whose development is shaped by a variety of environmental and genetic factors. While several recent studies suggest that microbial dysbiosis in the gut may promote asthma, little is known about the relationship between the recently discovered lung microbiome and asthma. Innate lymphoid cells (ILCs) have also been shown recently to participate in asthma. To investigate the relationship between the lung microbiome, ILCs, and asthma, we recruited 23 healthy controls (HC), 42 patients with non-severe asthma, and 32 patients with severe asthma. Flow cytometry analysis showed severe asthma associated with fewer natural cytotoxicity receptor (NCR)+ILC3s in the lung. Similar changes in other ILC subsets, macrophages, and monocytes were not observed. The asthma patients did not differ from the HC in terms of the alpha and beta-diversity of the lung and gut microbiomes. However, lung function correlated positively with both NCR+ILC3 frequencies and microbial diversity in the lung. Sputum NCR+ILC3 frequencies correlated positively with lung microbiome diversity in the HC, but this relationship was inversed in severe asthma. Together, these data suggest that airway NCR+ILC3s may contribute to a healthy commensal diversity and normal lung function.

Poseidonibacter parvus sp. nov., isolated from a squid.

A Gram-stain-negative, aerobic, short rod-shaped, motile, brownish-coloured bacterium, termed strain LPB0137T, was isolated from a squid. Its cells could grow weakly on marine agar 2216 with 0.04 % 2,3,5-triphenyl tetrazolium chloride (TTC). Each cell of strain LPB0137T has a circular chromosome with a length of 2.87 Mb and 27.7 mol% DNA G+C content. The genome includes 2698 protein-coding genes and six rRNA operons. In 16S rRNA gene sequence trees, strain LPB0137T formed a robust monophyletic clade with Poseidonibacter antarcticus SM1702T with a sequence similarity of 98.3 %. However, the average nucleotide identity and in silico DNA-DNA hybridization values between the two type strains were low (83.9 and 28.1 %, respectively). The overall phenotypic and genomic features of strain LPB0137T supported its assignment to the genus Poseidonibacter. However, the relatively low gene and genome sequence similarity between this strain and other type strains of the genus Poseidonibacter and several enzymatic characteristics indicated the taxonomic novelty of the isolated strain as a new member of the genus Poseidonibacter. Therefore, based on the phylogenetic and phenotypic characteristics of LPB0137T, we proposed a novel species of the genus Poseidonibacter for it, with the name Poseidonibacter parvus sp. nov. The type strain of this new species is thus LPB0137T (=KACC 18888T=JCM 31548T).

Respiratory microbiome profiles differ by recent hospitalization and nursing home residence in patients on mechanical ventilation.

BACKGROUND: Healthcare-associated pneumonia (HCAP) is a heterogeneous disease. We redefined nursing-home- and hospital-associated infections (NHAI) group by revising existing HCAP risk factors. The NHAI group comprised nursing home residents with a poor functional status, or recent (past 90 days) hospitalization or recent (past 180 days) antibiotic therapy. Our aim was to determine whether respiratory microbiota profiles are related to newly defined NHAI group in critically ill patients on mechanical ventilation. METHODS: The 180 endotracheal aspirates (ETAs) from 60 mechanically ventilated ICU patients (NHAI group, n = 24; non-NHAI group, n = 36) were prospectively collected on days 1, 3 and 7 in a university hospital. The bacterial community profiles of the ETAs were explored by 16S rRNA gene sequencing. A phylogenetic-tree-based microbiome association test (TMAT), generalized linear mixed models (GLMMs), the Wilcoxon test and the reference frame method were used to analyze the association between microbiome abundance and disease phenotype. RESULTS: The relative abundance of the genus Corynebacterium was significantly higher in the pneumonia than in the non-pneumonia group. The microbiome analysis revealed significantly lower α-diversity in the NHAI group than in the non-NHAI group. In the analysis of ß-diversity, the structure of the microbiome also differed significantly between the two groups (weighted UniFrac distance, Adonis, p < 0.001). The abundance of Corynebacterium was significantly higher, and the relative abundances of Granulicatella, Staphylococcus, Streptococcus and Veillonella were significantly lower, in the NHAI group than in the non-NHAI group. CONCLUSIONS: The microbiota signature of the ETAs distinguished between patients with and without risk factors for NHAI. The lung microbiome may serve as a therapeutic target for NHAI group.

Alteration of Lung and Gut Microbiota in IL-13-Transgenic Mice Simulating Chronic Asthma.

Increasing evidence suggests a potential role of microbial colonization in the inception of chronic airway diseases. However, it is not clear whether the lung and gut microbiome dysbiosis is coincidental or a result of mutual interaction. In this study, we investigated the airway microbiome in interleukin 13 (IL-13)-rich lung environment and related alterations of the gut microbiome. IL-13- overexpressing transgenic (TG) mice presented enhanced eosinophilic inflammatory responses and mucus production, together with airway hyperresponsiveness and subepithelial fibrosis. While bronchoalveolar lavage fluid and cecum samples obtained from 10-week-old IL-13 TG mice and their C57BL/6 wild-type (WT) littermates showed no significant differences in alpha diversity of lung and gut microbiome, they presented altered beta diversity in both lung and gut microbiota in the IL-13 TG mice compared to the WT mice. Lung-specific IL-13 overexpression also altered the composition of the gut as well as the lung microbiome. In particular, IL-13 TG mice showed an increased proportion of Proteobacteria and Cyanobacteria and a decreased amount of Bacteroidetes in the lungs, and depletion of Firmicutes and Proteobacteria in the gut. The patterns of polymicrobial interaction within the lung microbiota were different between WT and IL-13 TG mice. For instance, in IL-13 TG mice, lung Mesorhizobium significantly affected the alpha diversity of both lung and gut microbiomes. In summary, chronic asthma-like pathologic changes can alter the lung microbiota and affect the gut microbiome. These findings suggest that the lung-gut microbial axis might actually work in asthma.

Gemmobacter aquarius sp. nov., Runella rosea sp. nov. and Flavobacterium fluviale sp. nov., isolated from the Namhangang River system.

Three bacterial strains, namely HYN0069T, HYN0085T and HYN0086T, were isolated from freshwater samples taken from the Namhangan River system in Korea. 16S rRNA gene sequence similarities and phylogenetic tree topologies indicated that the three strains belonged to the genera Gemmobacter, Runella and Flavobacterium by showing the highest sequence similarities with Gemmobacter straminiformis (98.4 %), Runella aurantiaca (98.3 %) and Flavobacterium chungangense (98.1 %). No bacterial species with validly published names showed 98.7 % or higher sequence similarity with the novel isolates. The average nucleotide identities between the genome sequences of the three new isolates and the three closest neighbours were 80.2-92.0 %, all below the threshold for bacterial species delineation (95-96 %). Many biochemical and physiological features also discriminated the isolates from previously known species of the genera Gemmobacter, Runella and Flavobacterium. Based on the phylogenetic and phenotypic data presented in this study, we suggest three novel species with the following names: Gemmobacter aquarius sp. nov. (type strain HYN0069T=KACC 19488T=NBRC 113115T), Runella rosea sp. nov. (type strain HYN0085T=KACC 19490T=NBRC 113116T) and Flavobacterium fluviale sp. nov. (type strain HYN0086T=KACC 19489T=NBRC 113117T).

Sphingorhabdus lutea sp. nov., isolated from sea water.

A Gram-stain-negative, yellow-pigmented, aerobic bacterial strain, designated LPB0140T, was isolated from sea water. The 16S rRNA gene sequence similarity analysis demonstrated that the closest relative of the isolate is Sphingorhabdus contaminans (96.4 %), but the new isolate formed an independent phyletic line within the genus Sphingorhabdus. Its genome is composed of a circular chromosome of 2.53 Mb with DNA G+C content of 46.1 mol%. The genome includes 2359 protein-coding genes, and two copies of rRNA operons. Strain LPB0140T possessed C14 : 0 2-OH, C16 : 1ω7c and/or C16 : 1ω6c, and C18 : 1ω7c and/or C18 : 1ω6c as the major cellular fatty acids and Q-10 as the isoprenoid quinone. The major polar lipids were phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, and sphingoglycolipid, but phosphatidylmonomethylethanolamine and phosphatidyldimethylethanolamine were also detected as minor polar lipids. The chemotaxonomic properties and enzymatic activities of the novel isolate clearly differed from those of its closest relatives. Thus, based on the phylogenetic and phenotypic data presented in this study, strain LPB0140T should be classified as a novel species in the genus Sphingorhabdus. The type strain is LPB0140T (=KACC18891T=JCM31568T).