Characteristics of the Gut Microbiome of Healthy Young Male Soldiers in South Korea: The Effects of Smoking.

BACKGROUND/AIMS: South Korean soldiers are exposed to similar environmental factors. In this study, we sought to evaluate the gut microbiome of healthy young male soldiers (HYMS) and to identify the primary factors influencing the microbiome composition. METHODS: We prospectively collected stool from 100 HYMS and performed next-generation sequencing of the 16S rRNA genes of fecal bacteria. Clinical data, including data relating to the diet, smoking, drinking, and exercise, were collected. RESULTS: The relative abundances of the bacterial phyla Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria were 72.3%, 14.5%, 8.9%, and 4.0%, respectively. Fifteen species, most of which belonged to Firmicutes (87%), were detected in all examined subjects. Using cluster analysis, we found that the subjects could be divided into the two enterotypes based on the gut microbiome bacterial composition. Compared with enterotype 2 subjects, subjects classified as enterotype 1 tended to be characterized by higher frequencies of potentially harmful lifestyle habits (current smoker: 55.6% vs 36.6%, p=0.222; heavy drinker: 16.7% vs 3.7%, p=0.120; insufficient physical activity: 27.8% vs 14.6%, p=0.318). We identified a significant difference in the microbiome compositions of current and noncurrent smokers (p=0.008); the former differed from the latter mainly in a relatively lower abundance of Bifidobacterium species and a higher abundance of Negativicutes. CONCLUSIONS: A high abundance of Actinobacteria and low abundance of Bacteroidetes were the main features distinguishing the gut microbiomes of HYMS, and current smokers could be differentiated from noncurrent smokers by their lower abundance of Bifidobacterium and higher abundance of Negativicutes.

Blastococcus atacamensis sp. nov., a novel strain adapted to life in the Yungay core region of the Atacama Desert.

A polyphasic study was undertaken to establish the taxonomic status of a Blastococcus strain isolated from an extreme hyper-arid Atacama Desert soil. The isolate, strain P6T, was found to have chemotaxonomic and morphological properties consistent with its classification in the genus Blastococcus. It was shown to form a well-supported branch in the Blastococcus 16S rRNA gene tree together with the type strains of Blastococcus capsensis and Blastococcus saxobsidens and was distinguished from the latter, its close phylogenetic neighbour, by a broad range of phenotypic properties. The draft genome sequence of isolate P6T showed 84.6 % average nucleotide identity, 83.0 % average amino acid identity and a digital DNA-DNA hybridisation value of 27.8 % in comparison with the genome sequence of B. saxobsidens DSM 44509T, values consistent with its assignment to a separate species. Based on these data it is proposed that isolate P6T (NCIMB 15090T=NRRL B-65468T) be assigned to the genus Blastococcus as Blastococcus atacamensis sp. nov. Analysis of the whole genome sequence of B. atacamensis P6T, with 3778 open reading frames and a genome size of 3.9 Mb showed the presence of genes and gene clusters that encode for properties that reflect its adaptation to the extreme environmental conditions that prevail in Atacama Desert soils.

Marinobacterium marisflavi sp. nov., isolated from a costal seawater.

A marine bacterium designated strain IMCC4074(T) was isolated from surface seawater collected off Incheon Port, the Yellow Sea, and subjected to a polyphasic taxonomy. The strain was Gram-negative, chemoheterotrophic, slightly halophilic, strictly aerobic, and motile rods. Based on 16S rRNA gene sequence comparisons, the strain was most closely related to Marinobacterium litorale KCTC 12756(T) (93.9%) and shared low 16S rRNA gene sequence similarities with members of the genus Marinobacterium (91.8-93.9%) and the genus Neptunomonas (93.4%) in the order Oceanospirillales. Phylogenetic analyses showed that this marine isolate formed an independent phyletic line within the genus Marinobacterium clade. The DNA G+C composition of the strain was 56.0 mol% and the predominant constituents of the cellular fatty acids were C(16:0) (28.0%), C(16:1 )omega7c and/or iso-C(15:0) 2-OH (19.3%), C(18:1 )omega7c (17.8%), and C(17:1) cyclo (12.5%), which differentiated the strain from other Marinobacterium species. Based on the taxonomic data collected in this study, only a distant relationship could be found between strain IMCC4074(T) and other members of the genus Marinobacterium, thus the strain represents a novel species of the genus Marinobacterium, for which the name Marinobacterium marisflavi sp. nov. is proposed. The type strain of Marinobacterium marisflavi is IMCC4074(T) (= KCTC 12757(T) = LMG 23873(T)).

Sufflavibacter maritimus gen. nov., sp. nov., novel Flavobacteriaceae bacteria isolated from marine environments.

Four Gram-negative, chemoheterotrophic, nonmotile, yellow-colored strains were isolated from the East Sea or from deep-sea sediments of Nankai Trough by standard dilution plating. Characterization by polyphasic approaches indicated that the four strains are members of the same species. Phylogenetic analyses based on 16S rRNA gene sequences revealed that the strains formed a coherent and novel genus-level lineage within the family Flavobacteriaceae. The dominant cellular fatty acids were i-C15:0, 3-OH i-C17:0, and 2-OH i-C15:0 and/or C16:1 omega7c. Predominance of 2-OH i-C 15:0 and/or C16:1omega7c clearly differentiated the strains from closely related members. The DNA G+C contents ranged 35.1-36.2 mol%. It is proposed, from the polyphasic evidence, that the strains should be placed into a novel genus and species named Sufflavibacter maritimus gen. nov., sp. nov., with strain IMCC 1001T (=KCCM 42359T=NBRC 102039T) as the type strain.

Lutimonas vermicola gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from the marine polychaete Periserrula leucophryna.

A Gram-negative, yellow-coloured, non-motile, chemoheterotrophic, strictly aerobic, rod-shaped bacterium, designated IMCC1616(T), was isolated from the marine polychaete Periserrula leucophryna inhabiting tidal flat sediment of the Yellow Sea, and characterized by a polyphasic approach. The temperature, pH and NaCl ranges for growth were 3-37 degrees C, pH 5.0-11.0 and 0.5-7.5 %. Based on 16S rRNA gene sequence similarity analyses, the strain was most closely related to members of the genera Lutibacter (90.7 %), Tenacibaculum (89.2-90.4 %) and Polaribacter (88.4-90.2 %). Phylogenetic analysis using three treeing algorithms based on 16S rRNA gene sequences indicated that the strain formed a distinct lineage within the family Flavobacteriaceae. The DNA G+C content of the strain was 40.1 mol% and the predominant cellular fatty acids were iso-C(15 : 0) (16.5 %), anteiso-C(15 : 0) (10.9 %), iso-C(17 : 0) 3-OH (8.8 %) and iso-C(17 : 1) omega 9c (8.2 %). The DNA G+C content, large amount of iso-C(17 : 1) omega 9c and several phenotypic characteristics, including growth temperature and catalase activity, differentiated the strain from other related genera in the family. Therefore, from the taxonomic evidence collected in this study, it is proposed that strain IMCC1616(T) represents a new genus and species named Lutimonas vermicola gen. nov., sp. nov. The type strain of Lutimonas vermicola is strain IMCC1616(T) (=KCCM 42379(T) =NBRC 102041(T)).