Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River.
Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River. Three groups of samples, A, B and C. Every group has 3 replicates.
Project description:Despite the global importance of forests, it is virtually unknown how their soil microbial communities adapt at the phylogenetic and functional level to long term metal pollution. Studying twelve sites located along two distinct gradients of metal pollution in Southern Poland revealed that both community composition (via MiSeq Illumina sequencing of 16S rRNA genes) and functional gene potential (using GeoChip 4.2) were highly similar across the gradients despite drastically diverging metal contamination levels. Metal pollution level significantly impacted microbial community structure (p = 0.037), but not bacterial taxon richness. Metal pollution altered the relative abundance of specific bacterial taxa, including Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Planctomycetes and Proteobacteria. Also, a group of metal resistance genes showed significant correlations with metal concentrations in soil, although no clear impact of metal pollution levels on overall functional diversity and structure of microbial communities was observed. While screens of phylogenetic marker genes, such as 16S rRNA, provided only limited insight into resilience mechanisms, analysis of specific functional genes, e.g. involved in metal resistance, appeared to be a more promising strategy. This study showed that the effect of metal pollution on soil microbial communities was not straightforward, but could be filtered out from natural variation and habitat factors by multivariate statistical analysis and spatial sampling involving separate pollution gradients.
Project description:The increased urban pressures are often associated with specialization of microbial communities. Microbial communities being a critical player in the geochemical processes, makes it important to identify key environmental parameters that influence the community structure and its function.In this proect we study the influence of land use type and environmental parameters on the structure and function of microbial communities. The present study was conducted in an urban catchment, where the metal and pollutants levels are under allowable limits. The overall goal of this study is to understand the role of engineered physicochemical environment on the structure and function of microbial communities in urban storm-water canals. Microbial community structure was determined using PhyoChio (G3)
Project description:The increased urban pressures are often associated with specialization of microbial communities. Microbial communities being a critical player in the geochemical processes, makes it important to identify key environmental parameters that influence the community structure and its function.In this proect we study the influence of land use type and environmental parameters on the structure and function of microbial communities. The present study was conducted in an urban catchment, where the metal and pollutants levels are under allowable limits. The overall goal of this study is to understand the role of engineered physicochemical environment on the structure and function of microbial communities in urban storm-water canals. Microbial community structure was determined using PhyoChio (G3) Water and sediment samples were collected after a rain event from Sungei Ulu Pandan watershed of >25km2, which has two major land use types: Residential and industrial. Samples were analyzed for physicochemical variables and microbial community structure and composition. Microbial community structure was determined using PhyoChio (G3)
Project description:Despite the global importance of forests, it is virtually unknown how their soil microbial communities adapt at the phylogenetic and functional level to long term metal pollution. Studying twelve sites located along two distinct gradients of metal pollution in Southern Poland revealed that both community composition (via MiSeq Illumina sequencing of 16S rRNA genes) and functional gene potential (using GeoChip 4.2) were highly similar across the gradients despite drastically diverging metal contamination levels. Metal pollution level significantly impacted microbial community structure (p = 0.037), but not bacterial taxon richness. Metal pollution altered the relative abundance of specific bacterial taxa, including Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Planctomycetes and Proteobacteria. Also, a group of metal resistance genes showed significant correlations with metal concentrations in soil, although no clear impact of metal pollution levels on overall functional diversity and structure of microbial communities was observed. While screens of phylogenetic marker genes, such as 16S rRNA, provided only limited insight into resilience mechanisms, analysis of specific functional genes, e.g. involved in metal resistance, appeared to be a more promising strategy. This study showed that the effect of metal pollution on soil microbial communities was not straightforward, but could be filtered out from natural variation and habitat factors by multivariate statistical analysis and spatial sampling involving separate pollution gradients. 12 samples were collected from two long-term polluted areas (Olkusz and Miasteczko M-EM-^ZlM-DM-^Eskie) in Southern Poland. In the study presented here, a consecutively operated, well-defined cohort of 50 NSCLC cases, followed up more than five years, was used to acquire expression profiles of a total of 8,644 unique genes, leading to the successful construction of supervised
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance Two-condition experiments. Comparing samples after induction with heavy metals versus non-induced samples. Biological duplicate or triplicate. Each array contains 3 or 4 technical replicates.
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance
Project description:The commonly observed increased heavy metal tolerance of ectomycorrhized plants is usually linked with the protective role of the fungal hyphae covering colonized plant root tips. However, the molecular tolerance mechanisms in heavy metal stressed low-colonized ectormyocrrhizal plants characterized by an ectomycorrhiza-triggered increases in growth are unknown. Here, we examined <i>Populus × canescens</i> microcuttings inoculated with the <i>Paxillus involutus</i> isolate, which triggered an increase in poplar growth despite successful colonization of only 1.9% ± 0.8 of root tips. The analyzed plants, lacking a mantle-a protective fungal biofilter-were grown for 6 weeks in agar medium enriched with 0.75 mM Pb(NO<sub>3</sub>)<sub>2</sub>. In minimally colonized 'bare' roots, the proteome response to Pb was similar to that in noninoculated plants (e.g., higher abundances of PM- and V-type H<sup>+</sup> ATPases and lower abundance of ribosomal proteins). However, the more intensive activation of molecular processes leading to Pb sequestration or redirection of the root metabolic flux into amino acid and Pb chelate (phenolics and citrate) biosynthesis coexisted with lower Pb uptake compared to that in controls. The molecular Pb response of inoculated roots was more intense and effective than that of noninoculated roots in poplars.
Project description:Increased root H+ secretion is known as a strategy of plant adaption to low phosphorus (P) stress by enhancing mobilization of sparingly soluble P-sources. However, it remains fragmentarywhether enhanced H+ exudation could reconstruct the plant rhizosphere microbial community under low P stress. The present study found that P deficiency led to enhanced H+ exudation from soybean (Glycine max) roots. Three out of all eleven soybean H+-pyrophosphatases (GmVP) geneswere up-regulated by Pi starvation in soybean roots. Among them, GmVP2 showed the highest expression level under low P conditions. Transient expression of a GmVP2-green fluorescent protein chimera in tobacco (Nicotiana tabacum) leaves, and functional characterization of GmVP2 in transgenic soybean hairy roots demonstrated that GmVP2 encoded a plasma membrane transporter that mediated H+ exudation. Meanwhile, GmVP2-overexpression in Arabidopsis thaliana resulted in enhanced root H+ exudation, promoted plant growth, and improved sparingly soluble Ca-P utilization. Overexpression of GmVP2 also changed the rhizospheric microbial community structures, as reflected by a preferential accumulation of acidobacteria in the rhizosphere soils. These results suggested that GmVP2 mediated Pi-starvation responsive H+ exudation,which is not only involved in plant growth and mobilization of sparingly soluble P-sources, but also affects microbial community structures in soils.