The Genome of a Pathogenic Rhodococcus: Cooptive Virulence Underpinned by Key Gene Acquisitions

We report the genome of the facultative intracellular parasite Rhodococcus equi, the only animal pathogen within the biotechnologically important actinobacterial genus Rhodococcus. The 5.0-Mb R. equi 103S genome is significantly smaller than those of environmental rhodococci. This is due to genome expansion in nonpathogenic species, via a linear gain of paralogous genes and an accelerated genetic flux, rather than reductive evolution in R. equi. The 103S genome lacks the extensive catabolic and secondary metabolic complement of environmental rhodococci, and it displays unique adaptations for host colonization and competition in the short-chain fatty acid–rich intestine and manure of herbivores—two main R. equi reservoirs. Except for a few horizontally acquired (HGT) pathogenicity loci, including a cytoadhesive pilus determinant (rpl) and the virulence plasmid vap pathogenicity island (PAI) required for intramacrophage survival, most of the potential virulence-associated genes identified in R. equi are conserved in environmental rhodococci or have homologs in nonpathogenic Actinobacteria. This suggests a mechanism of virulence evolution based on the cooption of existing core actinobacterial traits, triggered by key host niche–adaptive HGT events. We tested this hypothesis by investigating R. equi virulence plasmid-chromosome crosstalk, by global transcription profiling and expression network analysis. Two chromosomal genes conserved in environmental rhodococci, encoding putative chorismate mutase and anthranilate synthase enzymes involved in aromatic amino acid biosynthesis, were strongly coregulated with vap PAI virulence genes and required for optimal proliferation in macrophages. The regulatory integration of chromosomal metabolic genes under the control of the HGT–acquired plasmid PAI is thus an important element in the cooptive virulence of R. equi

Effect of molten caustic leaching on demineralization and desulfurization of asphaltite

Molten caustic leaching process is effective in reducing significant amounts of ash-forming minerals, pyritic sulfur, and organic sulfur from solid fossil fuels. The effect of leaching asphaltite samples from Seguruk and Harbul collieries of Sirnak and Silopi asphaltite fields (situated in the Southeast Anatolia region of Turkey) with molten sodium hydroxide and followed by mild acid on demineralization and desulfurization was investigated. The effects of alkali/asphaltite ratio, time, and temperature on the leaching efficiency were detailed, and the experimental results are presented here. Chemical demineralization and desulfurization of asphaltite samples using molten sodium hydroxide were investigated in the temperature range of 200 degrees C-400 degrees C. The percentage of demineralization and desulfurization increased with the increase in alkali/asphaltite ratio. The removal of total sulfur and ash increased with increasing leaching temperature and time. Most of the inorganic sulfur and a significant portion of the organic sulfur were removed

Non-isothermal DSC and TG/DTG analysis of the combustion of Si̇lopi̇ asphaltites

In this research, non-isothermal combustion and kinetics of Silopi (Turkey) asphaltite samples were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG/DTG). A sample size of 10 mg, heating rates of 5, 10, 15 and 200C min(-1) were used in the temperature range of 20-600 degrees C, under air atmosphere. Two reaction regions were observed in DSC curves. The first region is due to the evaporation of moisture in asphaltite sample whereas, release of volatile matter and burning of carbon is called the second region

Low-temperature synthesis of MgB2 via powder metallurgy processing

Ball-milled Mg/B2O3 powder blends reveal interpenetrating layers of deformed magnesium and boron oxide grains that are increasingly refined with increasing milling time. Boron oxide is reduced by Mg and MgO thus formed reacts with the remaining B2O3 to produce Mg-3(BO3)(2) during ball milling for 30 min. Both B2O3 and Mg-3(BO3)(2) react with Mg to produce MgB2 upon further ball milling. An annealing treatment can be employed when ball milling is performed for less than 1 h as thermal exposure of the ball-milled Mg/B2O3 powder blends also leads to the formation of MgB2. The above reactions take place between 500 and 700 degrees C when the Mg/B2O3 powder blend is ball milled for 30 min, and between 450 and 550 degrees C, after ball milling for 1 h. This is a very attractive route owing to processing temperatures where the volatility of Mg is no longer a problem

Recent developments in the application of thermal analysis techniques in fossil fuels

In this review, application of thermal analysis techniques (differential scanning calorimetry, thermogravimetry, differential thermal analysis, etc.) for fossil fuel characterization and kinetics are reviewed between 2001 and 2006. The results presented clearly showed that thermal analysis applications are well-established techniques used in fossil fuel research area