Involvement of the flagellar assembly pathway in Vibrio alginolyticus adhesion under environmental stresses

The purpose of this study was to determine the concentrations and health risk of heavy metals in urban soils from a steel industrial district in China. A total of 115 topsoil samples from Anshan city, Liaoning, Northeast China were collected and analyzed for Cr, Cd, Pb, Zn, Cu, and Ni. The geoaccumulation index (Igeo), pollution index (PI), and potential ecological risk index (PER) were calculated to assess the pollution level in soils. The hazard index (HI) and carcinogenic risk (RI) were used to assess human health risk of heavy metals. The average concentration of Cr, Cd, Pb, Zn, Cu, and Ni were 69.9, 0.86, 45.1, 213, 52.3, and 33.5mg/kg, respectively. The Igeo and PI values of heavy metals were in the descending order of Cd>Zn>Cu>Pb>Ni>Cr. Higher Igeo value for Cd in soil indicated that Cd pollution was moderate. Pollution index indicated that urban soils were moderate to highly polluted by Cd, Zn, Cu, and Pb. The spatial distribution maps of heavy metals revealed that steel industrial district was the contamination hotspots. Principal component analysis (PCA) and matrix cluster analysis classified heavy metals into two groups, indicating common industrial sources for Cu, Zn, Pb, and Cd. Matrix cluster analysis classified the sampling sites into four groups. Sampling sites within steel industrial district showed much higher concentrations of heavy metals compared to the rest of sampling sites, indicating significant contamination introduced by steel industry on soils. The health risk assessment indicated that non-carcinogenic values were below the threshold values. The hazard index (HI) for children and adult has a descending order of Cr>Pb>Cd>Cu>Ni>Zn. Carcinogenic risks due to Cr, Cd, and Ni in urban soils were within acceptable range for adult. Carcinogenic risk value of Cr for children is slightly higher than the threshold value, indicating that children are facing slight threat of Cr. These results provide basic information of heavy metal pollution control and environment management in steel industrial regions.

Pathogens adapt to the host environment by altering their patterns of gene expression. Microarray-based and genetic techniques used to characterize bacterial gene expression during infection are limited in their ability to comprehensively and simultaneously monitor genome-wide transcription. We used massively parallel cDNA sequencing (RNA-seq) techniques to quantitatively catalog the transcriptome of the cholera pathogen, Vibrio cholerae, derived from two animal models of infection. Transcripts elevated in infected rabbits and mice relative to laboratory media derive from the major known V. cholerae virulence factors and also from genes and small RNAs not previously linked to virulence. The RNA-seq data was coupled with metabolite analysis of cecal fluid from infected rabbits to yield insights into the host environment encountered by the pathogen and the mechanisms controlling pathogen gene expression. RNA-seq-based transcriptome analysis of pathogens during infection produces a robust, sensitive, and accessible data set for evaluation of regulatory responses driving pathogenesis. Copyright © 2011 Elsevier Inc. All rights reserved.

Research on the behaviour of microorganisms in geogenic or anthropogenic metallomorphic environments is an integral part of geomicrobiology. The investigation of microbial impact on the fate of minerals and geologically significant compounds of mining areas can lead to an understanding of biogeochemical cycles. Metabolic processes of microorganisms are the cause for the dissolution of minerals, and especially pyrite oxidation results in the generation of acid mine drainage which, in turn, leads to heavy metal contamination as a result of mining activities. On the other hand, microbial metabolism can also contribute to the formation of certain ore deposits over geological time. The adaptation to heavy metal rich environments is resulting in microorgansims which show activities for biosorption, bioprecipitation, extracellular sequestration, transport mechanisms, and/or chelation. Such resistance mechanisms are the basis for the use of microorganisms in bioremediation approaches. As only a small part of the worldwide occurring prokaryotes has been described yet, the understanding of the role bacteria play in a geogenic and pedogenic context is very likely to change deeply as soon as more habitat relevant microbial functions can be described. Examples for the identification of microbial processes from case studies may help to advance this field. The strongly interdisciplinary field of bio-geo-interactions spanning from the microorganism to the mineral holds much promise for future developments in both basic research as well as applied sciences. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.