Project description:Leafy green vegetables, such as lettuce, have been increasingly implicated in outbreaks of foodborne illnesses due to contamination by Escherichia coli O157:H7. While E. coli can survive in soils, colonize plants, and survive on produce, very little is known about the interaction of E. coli with the roots of growing lettuce plants. In these studies a combination of microarray analyses and microbial genetics were used to gain a comprehensive understanding of bacterial genes involved in the colonization and growth of E. coli K12 on lettuce roots using a hydroponic assay system. Here we report that after three days of interaction with lettuce roots, 193 and 131 genes were significantly up-regulated and down-regulated at least 1.5 fold, respectively. Forty-five out of the 193 up-regulated genes (23%) were involved in protein synthesis and were highly induced. Genes involved in stress response, attachment and biofilm formation were up-regulated in E. coli when they interacted with lettuce roots under conditions of hydroponic growth. In particular crl, a gene regulating the cryptic csgA gene for curli production, was significantly up regulated. The crl, csgA and fliN mutants had a reduced capacity to attach to roots as determined by bacterial counts and by confocal laser scanning microscopy. Our microarray data showed that E. coli K12 increased the synthesis of proteins indicated that a dramatic change was induced in the physiology of the microorganism. This study indicates that E. coli K12 can efficiently colonize lettuce roots by using attachment and biofilm modulation genes and can readily adapt to the rhizosphere of lettuce plants. Further studies are needed to better characterize this interaction in pathogenic strains of this species. Escherichia coli MG1655 strains were grown in the lettuce rhizosphere for three days. Transcriptional profiling of E. coli was compared between cells grown with and without rhizosphere . Three biological replicates of each treatment were prepared, and six microarray slides were used.
Project description:We used wheat as rotational crop to assess the influence of continuous cropping on microbiome in Pinellia ternata rhizosphere and the remediation of rotational cropping to the impacted microbiota. Illumina high-throughput sequencing technology was utilized for this method to explore the rhizosphere microbial structure and diversity based on continuous and rotational cropping.
Project description:Microbial communities in the rhizosphere make significant contributions to crop health and nutrient cycling. However, their ability to perform important biogeochemical processes remains uncharacterized. Important functional genes, which characterize the rhizosphere microbial community, were identified to understand metabolic capabilities in the maize rhizosphere using GeoChip 3.0-based functional gene array method.
2014-09-12 | GSE61338 | GEO
Project description:microbial diversity in rhizosphere of lettuce
| PRJNA819191 | ENA
Project description:Microbial community diversity of lettuce rhizosphere
Project description:Leafy green vegetables, such as lettuce, have been increasingly implicated in outbreaks of foodborne illnesses due to contamination by Escherichia coli O157:H7. While E. coli can survive in soils, colonize plants, and survive on produce, very little is known about the interaction of E. coli with the roots of growing lettuce plants. In these studies a combination of microarray analyses and microbial genetics were used to gain a comprehensive understanding of bacterial genes involved in the colonization and growth of E. coli K12 on lettuce roots using a hydroponic assay system. Here we report that after three days of interaction with lettuce roots, 193 and 131 genes were significantly up-regulated and down-regulated at least 1.5 fold, respectively. Forty-five out of the 193 up-regulated genes (23%) were involved in protein synthesis and were highly induced. Genes involved in stress response, attachment and biofilm formation were up-regulated in E. coli when they interacted with lettuce roots under conditions of hydroponic growth. In particular crl, a gene regulating the cryptic csgA gene for curli production, was significantly up regulated. The crl, csgA and fliN mutants had a reduced capacity to attach to roots as determined by bacterial counts and by confocal laser scanning microscopy. Our microarray data showed that E. coli K12 increased the synthesis of proteins indicated that a dramatic change was induced in the physiology of the microorganism. This study indicates that E. coli K12 can efficiently colonize lettuce roots by using attachment and biofilm modulation genes and can readily adapt to the rhizosphere of lettuce plants. Further studies are needed to better characterize this interaction in pathogenic strains of this species.
Project description:Microbial communities in the rhizosphere make significant contributions to crop health and nutrient cycling. However, their ability to perform important biogeochemical processes remains uncharacterized. Important functional genes, which characterize the rhizosphere microbial community, were identified to understand metabolic capabilities in the maize rhizosphere using GeoChip 3.0-based functional gene array method. Triplicate samples were taken for both rhizosphere and bulk soil, in which each individual sample was a pool of four plants or soil cores. To determine the abundance of functional genes in the rhizosphere and bulk soils, GeoChip 3.0 was used.
Project description:Microbial communities in the rhizosphere make significant contributions to crop health and nutrient cycling. However, their ability to perform important biogeochemical processes remains uncharacterized. Important functional genes, which characterize the rhizosphere microbial community, were identified to understand metabolic capabilities in the maize rhizosphere using GeoChip 3.0-based functional gene array method. Triplicate samples were taken for both rhizosphere and bulk soil, in which each individual sample was a pool of four plants or soil cores. To determine the abundance of functional genes in the rhizosphere and bulk soils, GeoChip 3.0 was used.
Project description:Arsenic (As) bioavailability in the rice rhizosphere is influenced by many microbial interactions, particularly by metal-transforming functional groups at the root-soil interface. This study was conducted to examine As-transforming microbes and As-speciation in the rice rhizosphere compartments, in response to two different water management practices (continuous and intermittently flooded), established on fields with high to low soil-As concentration. Microbial functional gene composition in the rhizosphere and root-plaque compartments were characterized using the GeoChip 4.0 microarray. Arsenic speciation and concentrations were analyzed in the rhizosphere soil, root-plaque, porewater and grain samples. Results indicated that intermittent flooding significantly altered As-speciation in the rhizosphere, and reduced methyl-As and AsIII concentrations in the pore water, root-plaque and rice grain. Ordination and taxonomic analysis of detected gene-probes indicated that root-plaque and rhizosphere assembled significantly different metal-transforming functional groups. Taxonomic non-redundancy was evident, suggesting that As-reduction, -oxidation and -methylation processes were performed by different microbial groups. As-transformation was coupled to different biogeochemical cycling processes establishing functional non-redundancy of rice-rhizosphere microbiome in response to both rhizosphere compartmentalization and experimental treatments. This study confirmed diverse As-biotransformation at root-soil interface and provided novel insights on their responses to water management, which can be applied for mitigating As-bioavailability and accumulation in rice grains.
Project description:Verotoxigenic Escherichia coli (VTEC) are a leading cause of food-borne illness. Fruit and vegetables are recognised as an important source of the pathogen and can account for ~ 25 % of food-borne VTEC outbreaks, globally. The ability of VTEC to colonise leaves and roots of leafy vegetables, spinach (Spinacia oleracea) and lettuce (Lactuca sativa), was compared. The highest levels of colonisation occurred in the roots and rhizosphere, whereas colonisation of the leaves was lower and significantly different between the species. Colonisation of the leaves of prickly lettuce (L. serriola), a wild relative of domesticated lettuce, was especially poor. Differential VTEC gene expression in spinach extracts was markedly different for three tissue types, with little overlap. Comparison of expression in the same tissue type, cell wall polysaccharides, for lettuce and spinach also showed substantial differences, again with virtually no overlap. The transcriptional response was largely dependent on temperatures that are relevant to plant growth, not warm-blooded animals. The data show that VTEC adaptation to plant hosts and subsequent colonisation potential is underpinned by wholescale changes in gene expression that are specific to both plant tissue type and to the species.