Salegentibacter maritimus sp. nov., isolated from marine coastal sediment

Description of Aequorivita aurantiaca sp. nov. Isolated from Coastal Sediment, and Comparative Genomic Analysis and Biogeographic Distribution of the Genus Aequorivita

A novel Gram-stain-negative, facultatively anaerobic, and non-motile bacterial strain, designated SDUM287046T, was isolated from the coastal sediments of Jingzi Port of Weihai, China. Cells of strain SDUM287046T were rod-shaped with widths of 0.4-0.5 μm and lengths of 0.7-1.4 μm and could produce flexirubin-type pigments. Optimum growth of strain SDUM287046T occurred at 33-35 °C, pH 7.0, and with 2% (w/v) NaCl. Oxidase activity was negative, but catalase activity was positive. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain SDUM287046T was most closely related to Aequorivita aquimaris D-24T (98.3%). The main cellular fatty acids were iso-C15:0, anteiso-C15:0, iso-C17:0 3-OH, and summed feature 9 (comprised of iso-C17:1 ω9c and/or C16:0 10-methyl). The sole respiratory quinone was MK-6. The polar lipids consisted of phosphatidylethanolamine (PE), one aminolipid (AL), three unidentified glycolipids (GL), and three unidentified lipids (L). The DNA G + C content was 39.3 mol%. According to the integrated results of phylogenetic, physiological, biochemical, and chemotaxonomic characteristics, we propose that strain SDUM287046T represents a novel species of the genus Aequorivita, for which the name Aequorivita aurantiaca sp. nov. is proposed. The type strain is SDUM287046T (=KCTC 92754T = MCCC 1H01418T). Comparative genomic analysis showed that the 16 Aequorivita species shared 1453 core genes and differed mainly in amino acid metabolism, cofactor metabolism, and vitamin metabolism. Biogeographic distribution analysis indicated that the marine environments were the primary habitat of Aequorivita bacteria.

Microbial communities in carbonate precipitates from drip waters in Nerja Cave, Spain

Research on cave microorganisms has mainly focused on the microbial communities thriving on speleothems, rocks and sediments; however, drip water bacteria and calcite precipitation has received less attention. In this study, microbial communities of carbonate precipitates from drip waters in Nerja, a show cave close to the sea in southeastern Spain, were investigated. We observed a pronounced difference in the bacterial composition of the precipitates, depending on the galleries and halls. The most abundant phylum in the precipitates of the halls close to the cave entrance was Proteobacteria, due to the low depth of this sector, the direct influence of a garden on the top soil and the infiltration of waters into the cave, as well as the abundance of members of the order Hyphomicrobiales, dispersing from plant roots, and other Betaproteobacteria and Gammaproteobacteria, common soil inhabitants. The influence of marine aerosols explained the presence of Marinobacter, Idiomarina, Thalassobaculum, Altererythrobacter and other bacteria due to the short distance from the cave to the sea. Nineteen out of forty six genera identified in the cave have been reported to precipitate carbonate and likely have a role in mineral deposition.

Salegentibacter lacus sp. nov. and Salegentibacter tibetensis sp. nov., isolated from hypersaline lakes on the Tibetan Plateau

Two Gram-stain-negative, catalase- and oxidase-positive, rod-shaped and non-motile strains (LM13ST and JZCK2T) were isolated from hypersaline lakes in China. The colonies of both strains were yellow-pigmented and convex. Both strains could grow at 4–34 °C, pH 6.5–9.0 and with 1.0–13.0 % (w/v) NaCl. Comparisons based on 16S rRNA gene sequences showed that strains LM13ST and JZCK2T share less than 98.3 % similarity with species of the genus Salegentibacter . The phylogenetic tree reconstructed based on 16S rRNA gene sequences also showed that Salegentibacter species are the most closely related neighbours of strains LM13ST and JZCK2T. The sequenced draft genome sizes of strains LM13ST and JZCK2T are 4.06 and 4.22 Mbp with G+C contents of 37.0 and 37.8 mol%, respectively. The phylogenomic tree reconstructed using the Up-to-date Bacterial Core Gene set pipeline also demonstrated that both strains belong to the genus Salegentibacter . The calculated pairwise average nucleotide identity values and digital DNA–DNA hybridization values between strains LM13ST and JZCK2T and Salegentibacter species were less than 86.4 and 32.0 %, respectively. The respiratory quinone in both strains was MK-6. Their major fatty acids were iso-C12 : 0, iso-C14 : 0, C15 : 1  ω10c, iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and C17 : 1  ω10c. Their major polar lipids included phosphatidylethanolamine, one unidentified lipid and one unidentified aminolipid, but strain LM13ST also contained one more unidentified aminolipid, one more unidentified lipid and one unidentified phospholipid. Combining the above descriptions, strains LM13ST and JZCK2T should represent two independent novel species of the genus Salegentibacter , for which the names Salegentibacter lacus sp. nov. (type strain LM13ST=GDMCC 1.2643T=KCTC 82861T) and Salegentibacter tibetensis sp. nov. (type strain JZCK2T=GDMCC 1.2621T=KCTC 82862T) are proposed.