The development of a 16S rRNA gene based PCR for the identification of Streptococcus pneumoniae and comparison with four other species specific PCR assays

<p>Abstract</p> <p>Background</p> <p><it>Streptococcus pneumoniae </it>is one of the most frequently encountered pathogens in humans but its differentiation from closely related but less pathogenic streptococci remains a challenge.</p> <p>Methods</p> <p>This report describes a newly-developed PCR assay (Spne-PCR), amplifying a 217 bp product of the 16S rRNA gene of <it>S. pneumoniae</it>, and its performance compared to other genotypic and phenotypic tests.</p> <p>Results</p> <p>The new PCR assay designed in this study, proved to be specific at 57°C for <it>S. pneumoniae</it>, not amplifying <it>S. pseudopneumoniae </it>or any other streptococcal strain or any strains from other upper airway pathogenic species. PCR assays (psaA, LytA, ply, spn9802-PCR) were previously described for the specific amplification of <it>S. pneumoniae</it>, but <it>psaA</it>-PCR was the only one found not to cross-react with <it>S. pseudopneumoniae</it>.</p> <p>Conclusion</p> <p>Spne-PCR, developed for this study, and psaA-PCR were the only two assays which did not mis-identify <it>S. pseudopneumoniae </it>as <it>S. pneumoniae</it>. Four other PCR assays and the AccuProbe assay were unable to distinguish between these species.</p

Effect of alloy treatment and coiling temperature on microstructure and bending performance of ultra-high strength strip steel

Two different high strength B-containing microalloyed steel strips produced in industrial processing conditions, one treated with Ti and the other treated with Al, processed by controlled rolling, accelerated cooling and coiling in two different temperatures ranges [723 K to 733 K (450 °C to 460 °C)] and [633 K to 653 K (360 °C to 380 °C)] were subjected to bend testing. The Ti treated steel coiled at the higher temperature 733 K (460 °C) showed the best bending performance. The relatively softer (tensile strength of and even {112} in the sub-surface region as well as uniformity of through thickness texture of the rolled sheet improve the bendability. In the presence of crack initiators, like coarse and brittle TiN particles found in the Ti treated steel, a harder microstructure and the presence of Cube and Goss texture in the sub-surface layer, seen for the lower coiling temperature can cause local transgranular cleavage cracking. Finally the post-uniform elongation obtained from tensile testing and bendability follow a good correlation

Direct amplification of nodD from community DNA reveals the genetic diversity of Rhizobium leguminosarum in soil

Sequences of nodD, a gene found only in rhizobia, were amplified from total community DNA isolated from a pasture soil. The polymerase chain reaction (PCR) primers used, Y5 and Y6, match nodD from Rhizobium leguminosarum biovar trifolii, R. leguminosarum biovar viciae and Sinorhizobium meliloti. The PCR product was cloned and yielded 68 clones that were identified by restriction pattern as derived from biovar trifolii [11 restriction fragment length polymorphism (RFLP) types] and 15 clones identified as viciae (seven RFLP types). These identifications were confirmed by sequencing. There were no clones related to S. meliloti nodD. For comparison, 122 strains were isolated from nodules of white clover (Trifolium repens) growing at the field site, and 134 from nodules on trap plants of T. repens inoculated with the soil. The nodule isolates were of four nodD RFLP types, with 77% being of a single type. All four of these patterns were also found among the clones from soil DNA, and the same type was the most abundant, although it made up only 34% of the trifolii-like clones. We conclude that clover selects specific genotypes from the available soil population, and that R. leguminosarum biovar trifolii was approximately five times more abundant than biovar viciae in this pasture soil, whereas S. meliloti was rare