Nine thermophilic strains of aerobic, non-sporulating, heterotrophic bacteria were isolated after enrichment of chimney material sampled from a deep-sea hydrothermal field at a depth of 2634 m on the East-Pacific Rise (1 °N). The bacteria stained Gram-negative. They were rod-shaped and measured approximately 0.5 μm in width and 1.5–3.5 μm in length. They grew at 55–80 °C, pH 6–8 and 1–6 % NaCl. Optimal growth was observed at 70–75 °C, pH 7.0 and 1–3 % NaCl. The organisms were identified as members of the genus Rhodothermus, having a 16S rRNA gene similarity of 98.1 % with Rhodothermus marinus DSM 4252T. The novel isolates differed morphologically, physiologically and chemotaxonomically from R. marinus, e.g. in lack of pigmentation, response to hydrostatic pressure, maximum growth temperature and DNA G+C content. DNA–DNA hybridization revealed a reassociation value of 37.2 % between strain PRI 2902T and R. marinus DSM 4252T, which strongly suggested that they represent different species. Furthermore, AFLP fingerprinting separated the novel strains from R. marinus reference strains. It is therefore concluded that the strains described here should be classified as representatives of a novel species for which the name Rhodothermus profundi sp. nov. is proposed; the type strain is PRI 2902T (=DSM 22212T =JCM 15944T).
Five strains of strictly aerobic, heterotrophic bacteria that form pink–red colonies and are capable of hydrolysing pectin, xylan, laminarin, lichenan and starch were isolated from acidic Sphagnum peat bogs and were designated OB1010T, LCBR1, TPB6011T, TPB6028T and TPO1014T. Cells of these isolates were Gram-negative, non-motile rods that produced an amorphous extracellular polysaccharide-like substance. Old cultures contained spherical bodies of varying sizes, which represent starvation forms. Cells of all five strains were acidophilic and psychrotolerant, capable of growth at pH 3.0–7.5 (optimum pH 3.8–4.5) and at 2–33 °C (optimum 15–22 °C). The major fatty acids were iso-C15 : 0, C16 : 0 and summed feature 3 (C16 : 1 ω7c and/or iso-C15 : 0 2-OH). The major menaquinone detected was MK-8. The pigments were carotenoids. The genomic DNA G+C contents were 57.3–59.3 mol%. The five isolates were found to be members of subdivision 1 of the phylum Acidobacteria and displayed 95.3–98.9 % 16S rRNA gene sequence similarity to each other. The closest described relatives to strains OB1010T, LCBR1, TPB6011T, TPB6028T, and TPO1014T were members of the genera Terriglobus (94.6–95.8 % 16S rRNA gene sequence similarity) and Edaphobacter (94.2–95.4 %). Based on differences in cell morphology, phenotypic characteristics and hydrolytic capabilities, we propose a novel genus, Granulicella gen. nov., containing four novel species, Granulicella paludicola sp. nov. with type strain OB1010T (=DSM 22464T =LMG 25275T) and strain LCBR1, Granulicella pectinivorans sp. nov. with type strain TPB6011T (=VKM B-2509T =DSM 21001T), Granulicella rosea sp. nov. with type strain TPO1014T (=DSM 18704T =ATCC BAA-1396T) and Granulicella aggregans sp. nov. with type strain TPB6028T (=LMG 25274T =VKM B-2571T).