No abstract

A hydrogenogenic, carboxydotrophic marine bacterium, strain KKC1T, was isolated from a sediment core sample taken from a submerged marine caldera. Cells were non-motile, Gram-stain-negative, 1.0–3.0 µm straight rods, often observed with round endospores. Strain KKC1T grew at 55–68 °C, pH 5.2–9.2 and 0.8–14 % (w/v) salinity. Optimum growth occurred at 65 °C, pH 7.0–7.5 and 2.46 % salinity with a doubling time of 3.7 h. The isolate grew chemolithotrophically, producing H2 from carbon monoxide (CO) oxidation with reduction of various electron acceptors, e.g. sulfite, thiosulfate, fumarate, ferric iron and AQDS (9,10-anthraquinone 2,6-disulfonate). KKC1T grew heterotrophically on pyruvate, lactate, fumarate, glucose, fructose and mannose with thiosulfate as an electron acceptor. When grown mixotrophically on CO and pyruvate, C16 : 0 constituted almost half of the total cellular fatty acids. The DNA G+C content was 50.6 mol%. The 16S rRNA gene sequence of KKC1T was most closely related to those of members of the genus Moorella with similarity ranging from 91 to 89 %. Based on physiological and phylogenetic novelty, we propose the isolate as a representative of a new genus and novel species with the name Calderihabitans maritimus gen. nov., sp. nov.; the type strain of the type species is KKC1T ( = DSM 26464T = NBRC 109353T).

In hydrothermal environments, carbon monoxide (CO) utilisation by thermophilic hydrogenogenic carboxydotrophs may play an important role in microbial ecology by reducing toxic levels of CO and providing H 2 for fuelling microbial communities. We evaluated thermophilic hydrogenogenic carboxydotrophs by microbial community analysis. First, we analysed the correlation between carbon monoxide dehydrogenase (CODH)–energy-converting hydrogenase (ECH) gene cluster and taxonomic affiliation by surveying an increasing genomic database. We identified 71 genome-encoded CODH–ECH gene clusters, including 46 whose owners were not reported as hydrogenogenic carboxydotrophs. We identified 13 phylotypes showing > 98.7% identity with these taxa as potential hydrogenogenic carboxydotrophs in hot springs. Of these, Firmicutes phylotypes such as Parageobacillus , Carboxydocella , Caldanaerobacter, and Carboxydothermus were found in different environmental conditions and distinct microbial communities. The relative abundance of the potential thermophilic hydrogenogenic carboxydotrophs was low. Most of them did not show any symbiotic networks with other microbes, implying that their metabolic activities might be low. Electronic supplementary material The online version of this article (10.1007/s00203-019-01661-9) contains supplementary material, which is available to authorized users.

The genus Halobacillus, with the type species Halobacillus halophilus, was established and described by Spring and co-workers in 1996 (Claus et al., 1983;Spring et al., 1996). So far, nine species of this genus have been identified (Amoozegar et al., 2003a, b;Yoon et al., 2003Yoon et al., , 2004Yoon et al., , 2005Liu et al., 2005). The increasing number of publications on bio-applications and other aspects of Halobacillus and the large number of 16S rRNA gene sequences deposited in databases for unidentified species reflect the wide distribution of these bacteria and their considerable scientific interest (Burja et al., 1999;Pinar et al., 2001;Yang et al., 2002; Rivadeneyra et al., 2004). In our investigations of the diversity of halophilic bacteria in various habitats over the last few years, we obtained strains IS-Hb4 T and IS-Hb7 T in an endemic population from a carbonate rock collected at a deep-sea methane seep at Kuroshima Knoll, south-western Japan. Living in the special environment of low temperature, high pressure and low oxygen availability, these bacteria possess several features that are different from those of described species that would be considered evidence of interesting adaptation.Samples from which the bacteria were isolated, carbonate rocks authentically formed in a methane seep of the Kuroshima Knoll, located at 642 m depth at 24 u 07.89 N 124 u 11.29 E (Fujikura et al., 2003;Inagaki et al., 2004), were collected with the remotely operated vehicle Dolphin 3K, operated by the Japan Agency for Marine Earth Science and Abbreviation: CZE, capillary zone electrophoresis.

One new α-pyrone (nocapyrone R (1)), and three known γ-pyrones (nocapyrones B, H and L (2–4)) were isolated from the culture extract of a Nocardiopsis strain collected from marine sediment. Structures of these compounds were determined on the basis of spectroscopic data including NMR and MS. γ-Pyrones 2–4 were found to induce adiponectin production in murine ST-13 preadipocyte cells but the α-pyrone 1 had no activity. The absolute configuration of the anteiso-methyl branching in 4 was determined by HPLC comparison of a degraded product of 4 with standard samples as a 2:3 enantiomeric mixture of (R)- and (S)-isomers.