The hunt for a yet unknown: Common molecular signature in some genetically monomorphic enterobacteria.

Mark Achtman introduced the term "genetically monomorphic bacteria" (GM bacteria) for some human and plant pathogens. They displayed a great uniformity in terms of their "genetic" properties. This "uniformity" poses a challenge to microbiologists. To address these problems, we used CodonW and IslandViewer 3 as analytical tools and took Escherichia coli, Salmonella, and Shigella strains as a model organisms. We hypothesized that GM bacterium contains a common molecular signature among them. We have found a significant correlation regarding the number of protein-coding genes, predicted highly expressed genes, and the highest length of gene in this regard. On the other hand, the correspondence analysis of pathogenicity-related genes identified by IslandViewer 3 displayed a somewhat unique pattern in GM bacteria. The probable pathogenic genes are clustered into two separate groups, which is a hallmark of some pattern. Similar genes of non-monomorphic pathogenic strain clustered almost similarly, but the clusters are joined together, they are not completely separated. These features, in our considered view, may be considered as codon usages signatures of these bacteria, and E. coli in particular.

Antibacterial Activity of Green Synthesized Silver Nanoparticles Using Vasaka (Justicia adhatoda L.) Leaf Extract.

There is an increasing demand for silver nanoparticles due to its wide applicability in various area of biological science such as in field of antimicrobial and therapeutics, biosensing, drug delivery etc. To use in bioprocess the silver nanoparticles should be biocompatible and free from toxic chemicals. In the present study we report a cost effective and environment friendly route for green synthesis of silver nanoparticles using Vasaka (Justicia adhatoda L.) leaf extract as reducing as well as capping agent. This plant has been opted for the present study for its known medicinal properties and it is easily available. The biosynthesized silver nanoparticles are characterized by UV-Vis spectroscopy and TEM analysis. It is observed the nanoparticles are well shaped and the average particle size is 20 nm in the range of 5-50 nm. The antibacterial activity of these nanoparticles against Pseudomonas aeruginosa MTCC 741 has been measured by disc diffusion method, agar cup assay and serial dilution turbidity measurement assay. The results show green synthesized silver nanoparticles, using Vasaka leaf extract, have a potential to inhibit the growth of bacteria.

Analysis of codon usage patterns and predicted highly expressed genes for six phytopathogenic Xanthomonas genomes shows a high degree of conservation.

Members of the genus Xanthomonas are significant phytopathogens, which cause diseases in several economically important crops including rice, canola, tomato, citrus, etc. We have analyzed the genomes of six recently sequenced Xanthomonas strains for their synonymous codon usage patterns for all of protein coding genes and specific genes associated with pathogenesis, and determined the predicted highly expressed (PHX) genes by the use of the codon adaptation index (CAI). Our results show considerable heterogeneity among the genes of these moderately G+C rich genomes. Most of the genes were moderate to highly biased in their codon usage. However, unlike ribosomal protein genes, which were governed by translational selection, those genes associated with pathogenesis (GAP) were affected by mutational pressure and were predicted to have moderate to low expression levels. Only two out of 339 GAP genes were in the PHX category. PHX genes present in clusters of orthologous groups of proteins (COGs) were identified. Genes in the plasmids present in two strains showed moderate to low expression level and only a couple of genes featured in the PHX list. Common genes present in the top-20 PHX gene-list were identified and their possible functions are discussed. Correspondence analysis showed that genes are highly confined to a core in the plot.