Desulfurococcales
Ignisphaera aggregans gen. nov., sp. nov., a novel hyperthermophilic crenarchaeote isolated from hot springs in Rotorua and Tokaanu, New Zealand. (1/3)
Consortia containing a novel coccus-shaped, anaerobic heterotroph together with Pyrobaculum rods were cultivated from geothermal environments in New Zealand. Pure cultures of the cocci were only obtained from one such consortium, despite extensive attempts. Cells of this strain (AQ1.S1T) were regular to irregular cocci in morphology and occasionally formed large aggregates, especially when utilizing polysaccharides such as konjac glucomannan as a carbon source. Strain AQ1.S1T is a hyperthermophile, with an optimal temperature for growth between 92 and 95 degrees C (range 85-98 degrees C), and a moderate acidophile, with optimal growth occurring at pH 6.4 (range 5.4-7.0). Growth was inhibited by the addition of sulphur and NaCl (optimal growth occurred without addition of NaCl) and an electron acceptor was not required. Strain AQ1.S1T utilized starch, trypticase peptone, lactose, glucose, konjac glucomannan, mannose, galactose, maltose, glycogen and beta-cyclodextrin as carbon sources. The G+C content was 52.9 mol%. Based on 16S rRNA gene sequence analysis and physiological features it is proposed that isolate AQ1.S1T (=DSM 17230T=JCM 13409T) represents the type strain of a novel species of a new genus within the Crenarchaeota, Ignisphaera aggregans gen. nov., sp. nov. (+info)Isolation, characterization, and ecology of sulfur-respiring crenarchaea inhabiting acid-sulfate-chloride-containing geothermal springs in Yellowstone National Park. (2/3)
Elemental sulfur (S(0)) is associated with many geochemically diverse hot springs, yet little is known about the phylogeny, physiology, and ecology of the organisms involved in its cycling. Here we report the isolation, characterization, and ecology of two novel, S(0)-reducing Crenarchaea from an acid geothermal spring referred to as Dragon Spring. Isolate 18U65 grows optimally at 70 to 72 degrees C and at pH 2.5 to 3.0, while isolate 18D70 grows optimally at 81 degrees C and pH 3.0. Both isolates are chemoorganotrophs, dependent on complex peptide-containing carbon sources, S(0), and anaerobic conditions for respiration-dependent growth. Glycerol dialkyl glycerol tetraethers (GDGTs) containing four to six cyclopentyl rings were present in the lipid fraction of isolates 18U65 and 18D70. Physiological characterization suggests that the isolates are adapted to the physicochemical conditions of Dragon Spring and can utilize the natural organic matter in the spring as a carbon and energy source. Quantitative PCR analysis of 16S rRNA genes associated with the S(0) flocs recovered from several acid geothermal springs using isolate-specific primers indicates that these two populations together represent 17 to 37% of the floc-associated DNA. The physiological characteristics of isolates 18U65 and 18D70 are consistent with their potential widespread distribution and putative role in the cycling of sulfur in acid geothermal springs throughout the Yellowstone National Park geothermal complex. Based on phenotypic and genetic characterization, the designations Caldisphaera draconis sp. nov. and Acidilobus sulfurireducens sp. nov. are proposed for isolates 18U65 and 18D70, respectively. (+info)Pyrosequencing reveals high-temperature cellulolytic microbial consortia in Great Boiling Spring after in situ lignocellulose enrichment. (3/3)
(+info)Desulfurococcales is an order of extremophile archaea, characterized by their ability to grow under extreme conditions such as high temperatures and acidic environments. They are often found in geothermal areas such as hot springs and deep-sea hydrothermal vents. These organisms are able to oxidize sulfur compounds for energy and growth, and are therefore also known as sulfur-oxidizing archaea. The order Desulfurococcales belongs to the class Thermoprotei within the phylum Crenarchaeota.
Crenarchaeota is a phylum within the domain Archaea. Members of this group are typically extremophiles, living in harsh environments such as hot springs, deep-sea hydrothermal vents, and highly acidic or alkaline habitats. They are characterized by their unique archaeal-type rRNA genes and distinct cell wall composition. Some Crenarchaeota have been found to be involved in nitrogen and carbon cycling in various environments, including the ocean and soil. However, much is still unknown about this group due to the difficulty of culturing many of its members in the lab.