Splendidivirga corallicola gen. nov., sp. nov. and Agaribacillus aureus gen. nov., sp. nov., two bacteria isolated from coral Porites lutea, and proposal of Splendidivirgaceae fam. nov.

The Bacteroidota is one of the dominant bacterial phyla in corals. However, the exact taxa of those coral bacteria under the Bacteroidota are still unclear. Two aerobic, Gram-stain-negative, non-motile rods, designated strains BMA10T and BMA12T, were isolated from stony coral Porites lutea collected from Weizhou Island, PR China. Global alignment of 16S rRNA gene sequences indicated that both strains are closest to species of Fulvivirga with the highest identities being lower than 93 %, and the similarity value between these two strains was 92.3 %. Phylogenetic analysis based on 16S rRNA gene and genome sequences indicated that these two strains form an monophylogenetic lineage alongside the families Fulvivirgaceae, Reichenbachiellaceae, Roseivirgaceae, Marivirgaceae, Cyclobacteriaceae, and Cesiribacteraceae in the order Cytophagales, phylum Bacteroidota. The genomic DNA G+C contents of BMA10T and BMA12T were 38.4 and 41.9 mol%, respectively. The major polar lipids of BMA10T were phosphatidylethanolamine, unidentified aminophospholipid, four unidentified aminolipids, and five unidentified lipids. While those of BMA12T were phosphatidylethanolamine, two unidentified aminolipids, and five unidentified lipids. The major cellular fatty acids detected in both isolates were iso-C15 : 0 and C16 : 1 ω5c. Carbohydrate-active enzyme analysis indicated these two strains may utilize coral mucus or chitin. Based on above characteristics, these two strains are suggested to represent two new species in two new genera of a new family in the order Cytophagales, for which the name Splendidivirga corallicola gen. nov., sp. nov., Agaribacillus aureus gen. nov., sp. nov. and Splendidivirgaceae fam. nov. are proposed. The type strain of S. corallicola is BMA10T (=MCCC 1K08300T=KCTC 102045T), and that for A. aureus is BMA12T (=MCCC 1K08309T=KCTC 102046T).

Ferriphaselus amnicola strain GF-20, a new iron- and thiosulfate-oxidizing bacterium isolated from a hard rock aquifer.

Ferriphaselus amnicola GF-20 is the first Fe-oxidizing bacterium isolated from the continental subsurface. It was isolated from groundwater circulating at 20 m depth in the fractured-rock catchment observatory of Guidel-Ploemeur (France). Strain GF-20 is a neutrophilic, iron- and thiosulfate-oxidizer and grows autotrophically. The strain shows a preference for low oxygen concentrations, which suggests an adaptation to the limiting oxygen conditions of the subsurface. It produces extracellular stalks and dreads when grown with Fe(II) but does not secrete any structure when grown with thiosulfate. Phylogenetic analyses and genome comparisons revealed that strain GF-20 is affiliated with the species F. amnicola and is strikingly similar to F. amnicola strain OYT1, which was isolated from a groundwater seep in Japan. Based on the phenotypic and phylogenetic characteristics, we propose that GF-20 represents a new strain within the species F. amnicola.

Flavihumibacter fluminis sp. nov., a novel thermotolerant bacterium isolated from river silt.

A yellow, Gram-stain-positive, strictly aerobic, thermotolerant, non-motile and rod-shaped bacterial strain, designated RY-1T, was isolated from a silt sample of Fuyang River, Wuqiang County, Hengshui City, Hebei Province, PR China. Cells showed oxidase- and catalase-positive activities. Growth occurred at 20-45 °C (optimum, 37 °C) and pH 6.0-8.0 (optimum, pH 7.0), and in the presence of 0-1.5 % (w/v) NaCl (optimum, 0%). A phylogenetic tree based on 16S rRNA gene sequences revealed that strain RY-1T formed a phylogenetic lineage with Flavihumibacter members within the family Chitinophagaceae. A comparison of 16S rRNA gene sequences showed that strain RY-1T was most closely related to Flavihumibacter cheonanensis WS16T (98.6 %), Flavihumibacter sediminis CJ663T (97.7 %) and Flavihumibacter solisilvae 3-3T (97.6 %). The genome size of strain RY-1T was 4.71 Mb, and the DNA G+C content was 44.3  %. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values between strain RY-1T and reference strains were all lower than the threshold values for species delineation. Strain RY-1T contained menaquinone-7 and iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1G as the sole respiratory isoprenoid quinone and major cellular fatty acids (≥5 %), respectively. The major polar lipids consisted of phosphatidylethanolamine, three unidentified aminolipids and four unidentified lipids. According to the results of phenotypic, phylogenetic and chemotaxonomic characteristics, strain RY-1T represents a novel species of the genus Flavihumibacter, for which the name Flavihumibacter fluminis sp. nov. is proposed. The type strain is RY-1T (=GDMCC 1.2775T=JCM 34870T).

Parabacteroides faecalis sp. nov. Isolated from Swine Faeces.

A Gram-negative, obligate anaerobic, non-motile, non-spore-forming, rod-shaped bacterial strain designated AGMB00274T was isolated from swine faeces. An 16S rRNA gene analysis indicated that strain AGMB00274T belonged to the genus Parabacteroides, with the highest similarity to Parabacteroides johnsonii (P. johnsonii) DSM 18315T (sequence similarity of 94.9%). The genome size of strain AGMB00274T was 4,308,683 bp, with a DNA G+C content of 42.5 mol%. The biochemical analysis of strain AGMB00274T showed that it was positive for gelatin hydrolysis and α-fucosidase, but negative for the acid production from D-glucose, D-mannitol, D-maltose, salicin, glycerol, D-cellobiose, D-mannose, D-melezitose, D-sorbitol, D-trehalose, and negative for α-arabinosidase, glutamic acid decarboxylase, and pyroglutamic acid arylamidase. The dominant cellular fatty acids (> 10%) of the isolate were anteiso-C15: 0 (23.2%), iso-C15: 0 (16.6%), C18: 1 ω9c (16.4%), summed feature 11 (iso-C17: 0 3-OH and/or C18: 2 DMA) (12.5%), and C16: 0 (11.3%). The major respiratory quinones of strain AGMB00274T were MK-9 (55.4%) and MK-10 (44.6%). The major polar lipid was phosphatidylethanolamine. Based on phylogenetic, genetic, physiological, and chemotaxonomic analyses, as a novel species of the genus Parabacteroides, strain AGMB00274T was proposed with the name Parabacteroides faecalis sp. nov. The type strain used was AGMB00274T (= KCTC 25286T = GDMCC 1.2742T).

Gut microbiota and BMI throughout childhood: the role of firmicutes, bacteroidetes, and short-chain fatty acid producers.

Childhood obesity is a risk factor for numerous health conditions. A critical factor in the etiology of obesity appears to be the gut microbiota, which is the microbial community that resides in the human gut. The ratio of the phyla Firmicutes and Bacteroidetes (F/B) and gut bacterial genera that produce short-chain fatty acids (SCFA) have been suggested to contribute to obesity. The current study investigated (1) whether differences in F/B ratio can be observed in infancy and childhood in relation to zBMI in healthy children, and (2) whether an innovative proxy measure adds evidence to a relationship between SCFA producers and the etiology of obesity. Stool samples were collected at five time points, and zBMI was assessed at eight time points throughout the first 12 years of life. Our confirmatory analyses with Bayesian multilevel models showed no relationship between the F/B ratio and zBMI. Also, a proxy measure constructed from known SCFA producers was unrelated to zBMI throughout the first 12 years of life. Exploratory analyses using multilevel and random forest models suggest that the relative abundances of Firmicutes and Bacteroidetes were independently negatively associated with zBMI from infancy through childhood, and the SCFA producing genera Subdoligranulum and Alistipes were negatively related to future BMI in childhood.

Sabulibacter ruber gen. nov., sp. nov., a novel bacterium in the family Hymenobacteraceae, isolated from desert soil.

A novel Gram-stain-negative, aerobic, oxidase-positive, catalase-positive, non-motile, short rod-shaped, red-pigmented strain, designated as SYSU D00434T, was isolated from a dry sandy soil sample collected from the Gurbantunggut desert in Xinjiang, north-west PR China. Strain SYSU D00434T was found to grow at 4-37 °C (optimum, 28-30 °C), pH 6.0-8.0 (optimum, pH 7.0) and with 0-1.5 % (w/v) NaCl (optimum, 0-0.5 %). The predominant respiratory quinone was MK-7 and the major fatty acids (>10 %) were C16 : 1 ω5c, iso-C15 : 0, summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and summed feature 4 (anteiso-C17 : 1 B and/or iso-C17 : 1 I). The polar lipids consisted of phosphatidylethanolamine, two unidentified polar lipids, two unidentified aminolipids, two unidentified phospholipids and two unidentified glycolipids. The genomic DNA G+C content of strain SYSU D00434T was 50.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain SYSU D00434T belonged to the family Hymenobacteraceae, and shared a sequence similarity of less than 94.6 % to all validly named taxa. Based on the phenotypic, phylogenetic and chemotaxonomic properties, strain D00434T is proposed to represent a new species of a new genus, named Sabulibacter ruber gen. nov., sp. nov., within the family Hymenobacteraceae. The type strain is SYSU D00434T (=CGMCC 1.18624T=KCTC 82276T=MCCC 1K04975T).

Fulvivirga lutea sp. nov., a marine bacterium isolated from seawater.

A strictly aerobic, Gram-stain-negative, gliding, rod-shaped bacteria, designated strain S481T, was isolated from a surface seawater sample collected at Gunsan marina, in the West Sea of the Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain S481T formed a monophyletic clade with members of the genus Fulvivirga, showing 93.7-95.8% sequence similarity to the type strains. Strain S481T has a single circular chromosome of 4.13 Mbp with a DNA G+C content of 37.3 mol%. The values of average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization between strain S481T and all genome-sequenced species of the genus Fulvivirga were below 71.2%, 68.6% and 18.9%, respectively, indicating lower values than the standard cut-offs for species delineation. Growth was observed at 20-42 °C (optimum, 37 °C), at pH 6-8 (optimum, pH 7) and with 0 - 6 % NaCl (optimum, 1-2 %). The major fatty acids (>10%) were iso-C15:0, iso-C15:1 G and C16:1ω5c. The respiratory quinone was MK-7. The major polar lipids were identified as phosphatidylethanolamine, three unidentified aminolipids and five unidentified lipids. Based on the results of phenotypic characterization, phylogenetic analysis and genome-based comparison, strain S481T represents a novel species in the genus Fulvivirga, for which we propose the name Fulvivirga lutea sp. nov. The type strain is S481T (=KCTC 82209T=JCM 34505T).

Classification of Parabacteroides distasonis and other Bacteroidetes using O- antigen virulence gene: RfbA-Typing and hypothesis for pathogenic vs. probiotic strain differentiation.

Parabacteroides distasonis (Pdis) is the type species for the new Parabacteroides genus, and a gut commensal of the Bacteroidetes phylum. Emerging reports (primarily based on reference strain/ATCC-8503) concerningly propose that long-known opportunistic pathogen Pdis is a probiotic. We posit there is an urgent need to characterize the pathogenicity of Pdis strain-strain variability. Unfortunately, no methods/insights exist to classify Bacteroidetes for this purpose. Herein, we developed a virulence gene-based classification system for Pdis and Bacteroidetes to facilitate pathogenic-vs-probiotic characterization. We used DNA in silico methods to develop a system based on the virulence (lipopolysaccharide/bacterial wall) 'rfbA O-antigen-synthesis gene'. We then performed phylogenetic analysis of rfbA from fourteen Pdis complete genomes (21 genes), other Parabacteroides, Bacteroidetes, and Enterobacteriaceae; and proposed a PCR-based Restriction-Fragment Length Polymorphism method. Cluster analysis revealed that Pdis can be classified into four lineages (based on gene gaps/insertions) which we designated rfbA-Types I, II, III, and IV. In context, we found 14 additional rfbA-types (I-XVIII) interspersed with numerous Bacteroidetes and pathogenic Enterobacteriaceae forming three major "rfbA-superclusters." For laboratory rfbA-Typing implementation, we developed a PCR-primer strategy to amplify Pdis rfbA genes (100%-specificity) to conduct MboII-RFLP and sub-classify Pdis. In-silico primers for other Bacteroidetes are proposed/discussed. Comparative analysis of lipopolysaccharide/lipid-A gene lpxK confirmed rfbA as highly discriminant. In conclusion, rfbA-Typing classifies Bacteroidetes/Pdis into unique clusters/superclusters given rfbA copy/sequence variability. Analysis revealed that most pathogenic Pdis strains are single-copy rfbA-Type I . The relevance of the rfbA strain variability in disease might depend on their hypothetical modulatory interactions with other O-antigens/lipopolysaccharides and TLR4 lipopolysaccharide-receptors in human/animal cells.

Pontibacter pamirensis sp. nov., isolated from saline-alkaline soil.

A novel bacterium, designated TRT317T, was isolated from saline-alkaline soil collected from the Pamir plateau in northwest China. Cells of this strain were Gram-stain-negative, aerobic rods and red-pink-coloured. Phylogenetic analysis using 16S rRNA gene sequences indicated that strain TRT317T showed the highest sequence similarity to the type strains of Pontibacter diazotrophicus (96.3 %) and Pontibacter yuliensis (96.2 %). Growth was observed at 4-40 °C, pH 6.0-10.0 and in the presence of up to 7 % (w/v) NaCl. The major fatty acids were iso-C15 : 0 and summed feature 4 (iso-C17 : 1 I/anteiso-C17 : 1 B). The polar lipids included phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified phospholipid, four unidentified glycolipids and five unidentified lipids. The whole-cell sugars of strain TRT317T were mannose, rhamnose, glucose, galactose, xylose, arabinose and four unidentified sugars. The sole respiratory quinone was MK-7. The genomic DNA G+C content of strain TRT317T was 47.7 mol%. The average nucleotide identity (ANI) value of strain TRT317T with P. diazotrophicus was 88.3 %, which is below the standard ANI threshold for species identification (95-96 %). Combined results of physiological, genotypic, phylogenetic and chemotaxonomic analyses demonstrated that strain TRT317T represents a novel species within the genus Pontibacter, for which the name Pontibacter pamirensis sp. nov. is proposed. The type strain is TRT317T (=CGMCC1.18690T=KCTC 82818T).

Proteiniphilum propionicum sp. nov., a novel member of the phylum Bacteroidota isolated from pit clay used to produce Chinese liquor.

A novel, Gram-stain-negative, rod-shaped, strictly anaerobic bacterium of genus Proteiniphilum of the phylum Bacteroidota, named strain JNU-WLY501T, was isolated from pit clay used to produce strong aroma-type liquor in PR China. The genomic DNA G+C content and genome size of JNU-WLY501T were 41.4 % and 3.9 Mbp, respectively. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that JNU-WLY501T was closely related to Proteiniphilum acetatigenes DSM 18083T (95.7 %) and Proteiniphilum saccharofermentans M3/6T (94.9 %). The pairwise average nucleotide identity based on blast and average amino acid identity values of JNU-WLY501T compared with Proteiniphilum saccharofermentans M3/6T were 73.6 and 77.3 %, respectively, which both were lower than the threshold values for bacterial species delineation. The strain grew at 20-40 °C, with optimum growth at 37 °C. The pH range for growth was 5.4-9.1, with optimum growth at pH 7.5. The sodium chloride range for growth was 0.0-4.0 %, with optimum growth at 0 %. The strain did not use glucose, maltose, fructose or starch. Yeast extract, tryptone and peptone supported the growth of JNU-WLY501T, and the main fermentation products were acetate and propionate. The predominant cellular fatty acids (>5 %) of JNU-WLY501T were anteiso-C15 : 0 (30.6 %), anteiso-C17 : 0 (26.1 %), C16 : 0 (7.7 %), iso-C16 : 0 (5.0 %) and iso-C17 : 0 (5.0 %). The respiratory quinone of JNU-WLY501T was MK-5. On the basis of the morphological, physiological, biochemical, chemotaxonomic, genotypic and phylogenetic results, JNU-WLY501T represents a novel species of the genus Proteiniphilum, for which the name Proteiniphilum propionicum sp. nov. is proposed. The type strain is JNU-WLY501T (=GDMCC 1.2686T=JCM 34753T).

The Second Chromosome Promotes the Adaptation of the Genus Flammeovirga to Complex Environments.

Approximately 10% of bacterial strains contain more than one chromosome; however, in contrast to the primary chromosomes, the mechanisms underlying the formation of the second chromosomes and the significance of their existence remain unclear. Species of the genus Flammeovirga are typical polysaccharide-degrading bacteria, and herein, we report complete genome maps of this genus. These genomes all had multireplicons and second chromosomes. The second chromosome, much larger than plasmids and even megaplasmids, had rRNA and a disparity of 1% relative to the main chromosome in guanine-cytosine (GC) content. The largest chromosomes carried core genes for cellular processes, while the second chromosomes were enriched with genes involved in the transport and metabolism of inorganic ions and carbohydrates, particularly genes encoding glycoside hydrolases and polysaccharide lyases, which constituted the genetic basis for the strains' excellent capabilities to utilize polysaccharides. The second chromosomal evolution had a higher mutation rate than the primary chromosomes. Furthermore, the second chromosomes were also enriched in horizontal transfer genes and duplicated genes. The primary chromosomes were more evolutionarily conserved, while the second chromosomes were more plastic, which might be related to their different roles in the bacterial survival process. This study can be used as an example to explain possible formation mechanisms and functions of the second chromosomes, providing a reference for peer research on the second chromosomes. In particular, the second chromosomes were enriched in polysaccharide-degrading enzymes, which will provide theoretical support for using genomic data to mine tool-type carbohydrase resources. IMPORTANCE For decades, the typical bacterial genome has been thought to contain a single chromosome and a few small plasmids carrying nonessential genes. However, an increasing number of secondary chromosomes have been identified in various bacteria (e.g., plant symbiotic bacteria and human pathogens). This study reported three complete genomes of the polysaccharide-degrading marine bacterial genus Flammeovirga, revealed that they harbor two chromosomes, and further identified that the presence of a multireplicon system is a characteristic of complete Flammeovirga genomes. These sequences will add to our knowledge on secondary chromosomes, especially within Bacteroidetes. This study indicated that the second chromosomes of the genus Flammeovirga initially originated from an ancestral plasmid and subsequently expanded by gene duplication or by obtaining heterologous genes with functions, thus promoting host strains to adapt to complex living environments (e.g., to degrade more diverse polysaccharides from marine environments). These findings will promote the understanding of the evolution and function of bacteria with multireplicon systems.

Pontibacter aquaedesilientis sp. nov., isolated from Jeongbang Waterfall, Jeju Island.

A red-pigmented, aerobic, motile by gliding, pleomorphic to long-rods and divided by budding bacterium, Gram-stain negative bacterium, designated JH31T, was isolated from stream water of Jeongbang Waterfall, famous feature of Jeju Island, Republic of Korea. The cells grew at 9-40 °C (optimum, 28-30 °C), at pH 5.0-10.0 (pH 6.5-7.5) and with 0-6% NaCl (0% NaCl). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JH31T forms a lineage within the family Hymenobacteriaceae and clusters with its closest related species Pontibacter virorsus KCTC 42941T (98.1%), Pontibacter salisaro KACC 16885T (98.0%), Pontibacter amylolyticus JCM 19653T (97.2%), Pontibacter ramchanderi KACC 17384T (97.2%) and Pontibacter lucknowensis DM9T (96.4%). Strain JH31T produced carotenoid-type pigments but no flexirubin-type pigments. The genome was 4117105 bp long with 18 contigs and 3509 protein-coding genes. The DNA G+C content was 49.7 mol%. The digital DNA-DNA hybridization and average nucleotide identity values between the genome sequence of strain JH31T and its closely related reference strains were less than 19 and 72%, respectively. The draft genome of strain JH31T contained vital gene clusters involved in resistance against various metals, antibiotics, toxic compounds and radiation. The respiratory quinone of strain JH31T was menaquinone 7 and the predominant cellular fatty acids were iso-C15:0, and summed feature 4 (comprising iso-C17:1 I and/or anteiso B). The major polar lipids were phosphatidylethanolamine, three unidentified glycolipids, one unidentified phospholipid, one unidentified phosphoglycolipid and one unidentified aminoglycolipid. The phylogenetic, physiochemical and biochemical data showed that strain JH31T should represent a novel species in the genus Pontibacter, for which the name Pontibacter aquaedesilientis sp. nov. is proposed. The type strain for this novel species is JH31T (KACC 21705T=NBRC 114480T).

Molecular phylogeny of heritable symbionts and microbiota diversity analysis in phlebotominae sand flies and Culex nigripalpus from Colombia.

BACKGROUND: Secondary symbionts of insects include a range of bacteria and fungi that perform various functional roles on their hosts, such as fitness, tolerance to heat stress, susceptibility to insecticides and effects on reproduction. These endosymbionts could have the potential to shape microbial communites and high potential to develop strategies for mosquito-borne disease control. METHODOLOGY/PRINCIPAL FINDINGS: The relative frequency and molecular phylogeny of Wolbachia, Microsporidia and Cardinium were determined of phlebotomine sand flies and mosquitoes in two regions from Colombia. Illumina Miseq using the 16S rRNA gene as a biomarker was conducted to examine the microbiota. Different percentages of natural infection by Wolbachia, Cardinium, and Microsporidia in phlebotomines and mosquitoes were detected. Phylogenetic analysis of Wolbachia shows putative new strains of Lutzomyia gomezi (wLgom), Brumptomyia hamata (wBrham), and a putative new group associated with Culex nigripalpus (Cnig) from the Andean region, located in Supergroup A and Supergroup B, respectively. The sequences of Microsporidia were obtained of Pi. pia and Cx. nigripalpus, which are located on phylogeny in the IV clade (terrestrial origin). The Cardinium of Tr. triramula and Ps. shannoni were located in group C next to Culicoides sequences while Cardinium of Mi. cayennensis formed two putative new subgroups of Cardinium in group A. In total were obtained 550 bacterial amplicon sequence variants (ASVs) and 189 taxa to the genus level. The microbiota profiles of Sand flies and mosquitoes showed mainly at the phylum level to Proteobacteria (67.6%), Firmicutes (17.9%) and Actinobacteria (7.4%). High percentages of relative abundance for Wolbachia (30%-83%) in Lu. gomezi, Ev. dubitans, Mi. micropyga, Br. hamata, and Cx. nigripalpus were found. ASVs assigned as Microsporidia were found in greater abundance in Pi. pia (23%) and Cx. nigripalpus (11%). An important finding is the detection of Rickettsia in Pi. pia (58,8%) and Bartonella sp. in Cx. nigripalpus. CONCLUSIONS/SIGNIFICANCE: We found that Wolbachia infection significantly decreased the alpha diversity and negatively impacts the number of taxa on sand flies and Culex nigripalpus. The Principal Coordinate Analysis (PCoA) is consistent, which showed statistically significant differences (PERMANOVA, F = 2.4744; R2 = 0.18363; p-value = 0.007) between the microbiota of sand flies and mosquitoes depending on its origin, host and possibly for the abundance of some endosymbionts (Wolbachia, Rickettsia).

Pinibacter aurantiacus gen. nov., sp. nov., isolated from rhizospheric soil of a pine tree.

A Gram-stain-negative, aerobic and rod-shaped novel bacterial strain, designated MAH-26T, was isolated from rhizospheric soil of a pine tree. The colonies were orange coloured, smooth, spherical and 0.7-1.8 mm in diameter when grown on Reasoner's 2A (R2A) agar for 2 days. Strain MAH-26T was able to grow at 10-40 °C, at pH 6.0-9.0 and with 0-1.0 % NaCl. Cell growth occurred on nutrient agar, R2A agar, tryptone soya agar and Luria-Bertani agar. The strain gave positive results in oxidase and catalase tests. Strain MAH-26T was closely related to Flavihumibacter sediminis CJ663T and Parasegetibacter terrae SGM2-10T with a low 16S rRNA gene sequence similarity (92.8 and 92.9 %, respectively) and phylogenetic analysis indicated that the strain formed a distinct phylogenetic lineage from the members of the closely related genera of the family Chitinophagaceae. Strain MAH-26T has a draft genome size of 6 857 405 bp, annotated with 5173 protein-coding genes, 50 tRNA and two rRNA genes. The genomic DNA G+C content was 41.5 mol%. The predominant isoprenoid quinone was menaquinone 7. The major fatty acids were identified as iso-C15:0, iso-C15:1 G and iso-C17:0 3OH. On the basis of phylogenetic inference and phenotypic, chemotaxonomic and molecular properties, strain MAH-26T represents a novel species of a novel genus of the family Chitinophagaceae, for which the name Pinibacter aurantiacus gen. nov., sp. nov. is proposed. The type strain of Pinibacter aurantiacus is MAH-26T (=KACC 19749T=CGMCC 1.13701T).

Chitinophaga rhizophila sp. nov., isolated from rhizosphere soil of banana.

A Gram-stain-negative, aerobic and rod-shaped bacterium, designated as strain B61T, was isolated from rhizosphere soil of banana collected from Dongguan, Guangdong Province, PR China. Growth occurred at 15-40 °C, within a pH range of pH 6.0-9.0. Results of 16S rRNA gene sequence similarity and phylogenetic analyses showed that strain B61T was most closely related to 'Chitinophaga agri' KACC 21303 (98.9 %) and Chitinophaga pinensis DSM 2588T (98.8 %). The genome size was 7.6 Mb with a G+C content of 45.2 mol%. The genome-inferred average nucleotide identity values between strain B61T and two closely related strains were 79.2 and 79.3 %, respectively, with corresponding digital DNA-DNA hybridization values of 22.3 and 22.6 %. The major fatty acids of the novel strain were iso-C15:0, C16:1 ω5c and iso-C17:0 3-OH and the sole respiratory quinone was menaquinone 7 (MK-7). The polar lipids consisted of phosphatidylethanolamine, five unidentified aminolipids, four unidentified glycolipids and six unidentified lipids. The phenotypic and phylogenetic results clearly supported that strain B61T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga rhizophila, sp. nov. is proposed, with the type strain B61T (=GDMCC 1.2608T=KCTC 82856T).

Faecalibacter bovis sp. nov., isolated from cow faeces.

A Gram-stain-negative, non-spore-forming, yellow-pigmented, aerobic, pleomorphic rod-shaped bacterium, designated ZY171143T, was isolated from faeces of a cow with diarrhoea in Wenshan, Yunnan Province, south-west China and its taxonomic position was studied. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain ZY171143T belonged to the family Weeksellaceae and was most closely related to the only species of the genus Faecalibacter, Faecalibacter macacae CCTCC AB 2016016T with a sequence similarity of 97.8 %. The genomic OrthoANI and digital DNA-DNA hybridization values between the strain and F. macacae CCTCC AB 2016016T were 86.2 and 30.5 %, respectively. The genomic G+C content was 31.1 mol%. The predominant fatty acids (>5 %) were C15 : 0 iso, C17 : 0 iso 3OH, C16 : 0, C16 : 1 ω5c and summed feature 3 (C16 : 1 ω7c and/or 16 : 1 ω6c). The major polar lipids were phosphatidylethanolamine, triacylglycerol and sulfonolipid. The sole respiratory quinone was MK-6. These chemotaxonomic characterizations also revealed that strain ZY171143T was a member of the genus Faecalibacter. Based on the phenotypic, chemotaxonomic and genotypic data, strain ZY171143T represents a novel species within the genus Faecalibacter, for which the name Faecalibacter bovis sp. nov. is proposed. The type strain is ZY171143T (=CGMCC 1.13663T=KCTC 62642T).

Pontibacter cellulosilyticus sp. nov., a carboxymethyl cellulose-hydrolysing bacterium isolated from coastal water.

A Gram-stain-negative, rod-shaped, non-motile, red-pink bacterium designated SD6T was isolated from coastal marine water at Sadong Beach, Ulleung Island, South Korea. Cells of SD6T grew at 10-42 °C (optimum, 30 °C), pH 5.0-9.0 (optimum, pH 6.0-7.0) and at 0-8.0 % (w/v) NaCl (optimum, 0-3 %). Moreover, 16S rRNA gene sequence analysis indicated that strain SD6T was a member of the genus Pontibacter, sharing similarities to Pontibacter aydingkolensis XAAS-1T (98.0 %), Pontibacter amylolyticus 9-2T (97.3 %), Pontibacter korlensis X14-1T (97.2 %) and Pontibacter soli HYL7-26T (96.8 %). The predominant fatty acids of strain SD6T were identified as iso-C15 : 0 and summed feature 4 (comprising anteiso-C17 : 1 B and/or iso-C17 : 1 I) and the sole respiratory quinone was identified as MK-7 (menaquinone 7). Major polar lipids included phosphatidylethanolamine, one unidentified phosphoglycolipid, two unidentified glycolipids and one unidentified lipid. The average nucleotide identity and in silico DNA-DNA hybridization values of strain SD6T with its closely related strains were 72.8-79.8 % and 19.2-22.6 %, respectively. The genomic DNA G+C content was 45.4 mol%. In accordance with the results of phenotypic, chemotaxonomic and phylogenetic data, strain SD6T represents a novel species of the genus Pontibacter, for which the name Pontibacter cellulosilyticus sp. nov. is proposed. The type strain is SD6T (=KACC 21543T=NBRC 114313T=JCM 31022T).

COVID-19 Infection Alters the Microbiome: Elite Athletes and Sedentary Patients Have Similar Bacterial Flora.

Regular exercise can upgrade the efficiency of the immune system and beneficially alter the composition of the gastro-intestinal microbiome. We tested the hypothesis that active athletes have a more diverse microbiome than sedentary subjects, which could provide better protection against COVID-19 during infection. Twenty active competing athletes (CA) (16 male and 4 females of the national first and second leagues), aged 24.15 ± 4.7 years, and 20 sedentary subjects (SED) (15 male and 5 females), aged 27.75 ± 7.5 years, who had been diagnosed as positive for COVID-19 by a PCR test, served as subjects for the study. Fecal samples collected five to eight days after diagnosis and three weeks after a negative COVID-19 PCR test were used for microbiome analysis. Except for two individuals, all subjects reported very mild and/or mild symptoms of COVID-19 and stayed at home under quarantine. Significant differences were not found in the bacterial flora of trained and untrained subjects. On the other hand, during COVID-19 infection, at the phylum level, the relative abundance of Bacteroidetes was elevated during COVID-19 compared to the level measured three weeks after a negative PCR test (p < 0.05) when all subjects were included in the statistical analysis. Since it is known that Bacteroidetes can suppress toll-like receptor 4 and ACE2-dependent signaling, thus enhancing resistance against pro-inflammatory cytokines, it is suggested that Bacteroidetes provide protection against severe COVID-19 infection. There is no difference in the microbiome bacterial flora of trained and untrained subjects during and after a mild level of COVID-19 infection.

Limnovirga soli gen. nov., sp. nov., isolated from river sediment.

A cream-coloured, Gram-stain-negative, rod-shaped bacterium, designated strain KSC-6T, was isolated from soil sampled at the Gapcheon River watershed in Daejeon, Republic of Korea. The organism does not require NaCl for growth and grows at pH 6.0-8.0 (optimum, pH 7.0) and 10-37 °C (optimum, 25 °C). Phylogenetic trees based on the 16S rRNA gene sequences reveal that strain KSC-6T belongs to the family Chitinophagaceae within the order Chitinophagales and is most closely related to Panacibacter ginsenosidivorans Gsoil 1550T (95.9% similarity). The genomic DNA G+C content was 38.9 mol%. The major cellular fatty acids (>8 %) of strain KCS-6T were iso-C15:0, iso-C15 : 1 G and iso-C17 : 0 3-OH. The predominant respiratory quinone was menaquinone 7 and the predominant polar lipids were phosphatidylethanolamine, five unidentified aminolipids and two unidentified lipids. Based on genome analyses, low digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity values with closely related genera, and differential chemotaxonomic and physiological properties, we suggest that strain KCS-6T represents a novel species in a new genus in the family Chitinophagaceae, for which the name Limnovirga soli gen. nov., sp. nov. (type strain KCS-6T=KCCM 43337T=NBRC 114336T) is proposed.

Rhodocaloribacter litoris gen. nov., sp. nov., isolated from an intertidal hot spring.

Red-pigmented strains of non-sporeforming, aerobic, chemoorganotrophic bacteria were isolated from intertidal hot springs in Laugarvík, NW-Iceland. Cells stained Gram-negative and formed pleomorphic rods that often had swollen ends and occurred singly or in filaments. Growth was observed at 40-65 °C (optimum at 60 °C), pH 6-9 (optimum at 6.5-8) and 0.5-5% (optimum at 1-2%) (w/v) NaCl. Strain ISCAR-4553T contained MK-7 as the main respiratory quinone and saturated iso and anteiso branched chains of 17 and 15 carbons as the main cellular fatty acids (83.4%). The G+C content of the DNA is 67.3 mol%. The highest 16S rRNA gene sequence similarity was with the genus Roseithermus (92.0%) and followed by Rhodothermus, Rubrivirga and Rubricoccus (88-90%). Genome and phenotype comparisons supported the affiliation of the novel isolates and the genus Roseithermus to the family Rhodothermaceae of the phylum Rhodothermaeota. The described isolates are proposed to be classified as representatives of a novel species belonging to a novel genus, with the name Rhodocaloribacter litoris gen. nov., sp. nov. The type strain is ISCAR-4553T (=DSM 110790T = ATCC TSD-179T).