Supercritical water oxidation of high concentrations of phenol.

Decomposition of phenol at a concentration as high as 2 wt.% was effected by supercritical water oxidation at 25 MPa. Reaction temperatures ranged from 623-723 K and residence times were varied from 6.5 to 26 s. Oxygen was added in an equivalent amount to investigate reaction intermediates. The degree of phenol decomposition and reaction product were measured. Although tarry material production was observed, phenol decomposition conversion was predicted well by the reaction rate equations developed by previous researchers who conducted experiments at lower concentrations. Difference from low concentration phenol oxidation was found in the reaction product distribution and tarry material production. One possible explanation for this result is that the initiation of phenol decomposition is the same regardless of phenol concentration but that the succeeding radical reactions are different. The additive reaction between aromatic compounds was enhanced by high phenol concentration.

Pyrobaculum oguniense sp. nov., a novel facultatively aerobic and hyperthermophilic archaeon growing at up to 97 degrees C.

A novel hyperthermophilic, heterotrophic, rod-shaped archaeon was isolated from a terrestrial hot spring at Oguni-cho, Kumamoto Prefecture, Japan. The new isolate, strain TE7T, grew under aerobic, microaerobic and anaerobic conditions. Isolate TE7T grew optimally at 90-94 degrees C and pH 7.0-7.5 (adjusted at 25 degrees C) under atmospheric air with vigorous shaking. Strain TE7T cells were motile rods 2-10 microm in length and covered with a surface-layer lattice. Cell yields at 90 degrees C under aerobic conditions were twice that under anaerobic conditions. Under aerobic conditions, growth was inhibited by elemental sulfur, but thiosulfate stimulated growth. Under anaerobic conditions, no growth was observed in the presence of nitrate and nitrite, but elemental sulfur, thiosulfate, L-cystine and oxidized glutathione stimulated growth. The 16S rDNA sequence of TE7T exhibited a close relationship to the sequences of Pyrobaculum aerophilum and Thermoproteus neutrophilus, which belong to the cluster of the genus Pyrobaculum. DNA-DNA hybridization analysis showed a low level of DNA similarity between TE7T and previously described Pyrobaculum species. As TE7T is phenotypically and phylogenetically different from the other members of this genus, it is described as a new species named Pyrobaculum oguniense (type strain TE7T = JCM 10595T = DSM 13380T).

Acquired thermotolerance and temperature-induced protein accumulation in the extremely thermophilic bacterium Rhodothermus obamensis.

Temperature-induced changes in thermotolerance and protein composition were examined in heat-shocked cells and high-temperature-grown cells of the extremely thermophilic bacterium Rhodothermus obamensis. The survival at temperatures superoptimal for growth (90 and 95 degrees C) was enhanced in both heat-shocked cells and high-temperature-grown cells relative to that of cells grown at optimal temperatures. In a comparison of protein composition using two-dimensional gel electrophoresis, putative heat shock proteins (HSPs) and high-temperature growth-specific proteins (HGPs) were detected. N-terminal amino acid sequence analysis revealed that the putative HSPs were quite similar to the ATP-binding subunits of ABC transporters and the HGPs were proteins corresponding to domains II and III of elongation factor Tu. These results suggested that this extreme thermophile has developed temperature-induced responses that include increased survival under hyperthermal conditions, changes in protein composition, and also the production of novel HSPs.