A novel thermophilic, chemoheterotrophic, Gram-negative-staining, multicellular filamentous bacterium, designated strain 110ST, was isolated from an iron-rich coastal hydrothermal field in Japan. The isolate is facultatively aerobic and chemoheterotrophic. Phylogenetic analysis using 16S rRNA gene sequences nested strain 110ST in a novel class-level clone cluster of the phylum ‘ Chloroflexi ’. The isolate grows by dissimilatory iron- and nitrate-reduction under anaerobic conditions, which is the first report of these abilities in the phylum ‘ Chloroflexi ’. The organism is capable of growth with oxygen, ferric iron and nitrate as a possible electron acceptor, has a wide range of growth temperatures, and tolerates higher NaCl concentrations for growth compared to the other isolates in the phylum. Using phenotypic and phylogenetic data, strain 110ST ( = JCM 17282T = NBRC 107679T = DSM 23922T = KCTC 23289T = ATCC BAA-2145T) is proposed as the type strain of a novel species in a new genus, Ardenticatena maritima gen. nov., sp. nov. In addition, as strain 110ST apparently constitutes a new class of the phylum ‘ Chloroflexi ’ with other related uncultivated clone sequences, we propose Ardenticatenia classis nov. and the subordinate taxa Ardenticatenales ord. nov. and Ardenticatenaceae fam. nov.

A monobromoacetic acid-resistant bacterium, Bacillus strain I37c, was isolated from a marine sediment core. The strain grew in a medium containing 1.8 mg mL −1 of monobromoacetic acid. It produced constitutively a 2-haloacid dehalogenase that catalyzed the dehalogenation of monobromoacetic acid, monochloroacetic acid, and both L-and D-2-chloropropionic acid. The optimal pH and temperature for the activity measured using a partly purified enzyme were similar to those of known group I haloacid dehalogenases.

Physicochemical characteristics and archaeal and bacterial community structures in an iron-rich coastal hydrothermal field, where the temperature of the most active hot spot reaches above 100°C, were investigated to obtain fundamental information on microbes inhabiting a coastal hydrothermal field. The environmental settings of the coastal hydrothermal field were similar in some degree to those of deep-sea hydrothermal environments because of its emission of H2, CO2, and sulfide from the bottom of the hot spot. The results of clone analyses based on the 16S rRNA gene led us to speculate the presence of a chemo-synthetic microbial ecosystem, where chemolithoautotrophic thermophiles, primarily the bacterial order Aquificales, function as primary producers using H2 or sulfur compounds as their energy source and CO2 as their carbon source, and the organic compounds synthesized by them support the growth of chemoheterotrophic thermophiles, such as members of the order Thermales and the family Desulfurococcaceae. In addition, the dominance of members of the bacterial genus Herbaspirillum in the high temperature bottom layer led us to speculate the temporal formation of mesophilic zones where they can also function as primary producing or nitrogen-fixing bacteria.