A thermophilic, aerobic, Gram-stain-positive bacterium (strain PM5T), which formed mycelia of irregularly branched filaments and produced multiple exospores per cell, was isolated from a geothermally heated biofilm. Strain PM5T grew at 40–65 °C and pH 4.1–8.0, with optimal growth at 55 °C and pH 6.0. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain PM5T belonged to the class Ktedonobacteria , and was related most closely to Thermogemmatispora onikobensis ONI-1T (97.7 % similarity) and Thermogemmatispora foliorum ONI-5T (96.1 %). Morphological features and fatty acid profiles (major fatty acids: iso-C17 : 0, iso-C19 : 0 and 12,17-dimethyl C18 : 0) supported the affiliation of strain PM5T to the genus Thermogemmatispora . Strain PM5T oxidized carbon monoxide [CO; 10±1 nmol h−1 (mg protein)−1], but did not grow with CO as a sole carbon and energy source. Results from analyses of related strains indicated that the capacity for CO uptake occurred commonly among the members of the class Ktedonobacteria ; 13 of 14 strains tested consumed CO or harboured coxL genes that potentially enabled CO oxidation. The results of DNA–DNA hybridization and physiological and biochemical tests allowed the genotypic and phenotypic differentiation of strain PM5T from the two recognized species of the genus Thermogemmatispora . Strain PM5T differed from Thermogemmatispora onikobensis ONI-1T in its production of orange pigment, lower temperature optimum, hydrolysis of casein and starch, inability to grow with mannitol, xylose or rhamnose as sole carbon sources, and utilization of organic acids and amino acids. Strain PM5T is therefore considered to represent a novel species, for which the name Thermogemmatispora carboxidivorans sp. nov. is proposed. The type strain is PM5T ( = DSM 45816T = ATCC BAA-2534T).

Two thermophilic, Gram-stain-positive, rod-shaped, non-spore-forming bacteria (strains KI3T and KI4T) were isolated from geothermally heated biofilms growing on a tumulus in the Kilauea Iki pit crater on the flank of Kilauea Volcano (Hawai‘i, USA). Strain KI3T grew over an examined temperature range of 50–70 °C (no growth at 80 °C) and a pH range of 6.0–9.0, with optimum growth at 70 °C and pH 7.0. Strain KI4T grew at temperatures of 55–70 °C and a pH range of 5.8–8.0, with optimum growth at 65 °C and pH 6.7–7.1. The DNA G+C contents of strains KI3T and KI4T were 66.0 and 60.7 mol%, respectively. The major fatty acid for both strains was 12-methyl C18 : 0. Polar lipids in strain KI3T were dominated by glycolipids and phosphatidylinositol, while phosphatidylinositol and phosphoglycolipids dominated in strain KI4T. Strain KI3T oxidized carbon monoxide [6.7±0.8 nmol CO h−1 (mg protein)−1], but strain KI4T did not. 16S rRNA gene sequence analyses determined that the strains belong to the class Thermomicrobia , and that strains KI3T and KI4T are related most closely to Thermomicrobium roseum DSM 5159T (96.5 and 91.1 % similarity, respectively). 16S rRNA gene sequence similarity between strain KI3T and strain KI4T was 91.4 %. Phenotypic features and phylogenetic analyses supported the affiliation of strain KI3T to the genus Thermomicrobium , while results of chemotaxonomic, physiological and biochemical assays differentiated strains KI3T and KI4T from Thermomicrobium roseum . Strain KI3T ( = DSM 27067T = ATCC BAA-2535T) is thus considered to be the type strain of a novel species, for which the name Thermomicrobium carboxidum sp. nov. is proposed. Additionally, the characterization and phylogenetic position of strain KI4T showed that it represents a novel species of a new genus, for which the name Thermorudis peleae gen. nov., sp. nov. is proposed. The type strain of Thermorudis peleae is KI4T ( = DSM 27169T = ATCC BAA-2536T).

Ecosystem succession on a large deposit of volcanic cinders emplaced on Kilauea Volcano in 1959 has resulted in a mosaic of closed-canopy forested patches and contiguous unvegetated patches. Unvegetated and unshaded surface cinders (Bare) experience substantial diurnal temperature oscillations ranging from moderate (16 1C) to extreme (55 1C) conditions. The surface material of adjacent vegetated patches (Canopy) experiences much smaller fluctuations (14-25 1C) due to shading. To determine whether surface material from these sites showed adaptations by carbon monoxide (CO) and hydrogen (H 2 ) consumption to changes in ambient temperature regimes accompanying succession, we measured responses of CO and H 2 uptake to short-term variations in temperature and long-term incubations at elevated temperature. Based on its broader temperature optimum and lower activation energy, Canopy H 2 uptake was less sensitive than Bare H 2 uptake to temperature changes. In contrast, Bare and Canopy CO uptake responded similarly to temperature during short-term incubations, indicating no differences in temperature sensitivity. However, during extended incubations at 55 1C, CO uptake increased for Canopy but not Bare material, which indicated that the former was capable of thermal adaptation. H 2 uptake for material from both sites was completely inhibited at 55 1C throughout extended incubations. These results indicated that plant development during succession did not elicit differences in short-term temperature responses for Bare and Canopy CO uptake, in spite of previously reported differences in CO oxidizer community composition, and differences in average daily and extreme temperatures. Differences associated with vegetation due to succession did, however, lead to a notable capacity for thermophilic CO uptake by Canopy but not Bare material.

No abstract

No abstract