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: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:Rhizosphere is a complex system of interactions between plant roots, bacteria, fungi and animals, where the release of plant root exudates stimulates bacterial density and diversity. However, the majority of the bacteria in soil results to be unculturable but active. The aim of the present work was to characterize the microbial community associated to the root of V. vinifera cv. Pinot Noir not only under a taxonomic perspective, but also under a functional point of view, using a metaproteome approach. Our results underlined the difference between the metagenomic and metaproteomic approach and the large potentiality of proteomics in describing the environmental bacterial community and its activity. In fact, by this approach, that allows to investigate the mechanisms occurring in the rhizosphere, we showed that bacteria belonging to Streptomyces, Bacillus and Pseudomonas genera are the most active in protein expression. In the rhizosphere, the identified genera were involved mainly in phosphorus and nitrogen soil metabolism.
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.
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 surface enhanced Raman spectroscopy (SERS) were used to gain a comprehensive understanding of bacterial genes involved in the colonization and growth of E. coli O157:H7 on lettuce roots and compared to E. coli K12 using a hydroponic system (HS) which we have reported in the previous studies. Using microarray, after three days of interaction with lettuce roots, 94 and 109 genes of E. coli O157:H7 were significantly up-regulated and down-regulated at least 1.5 fold, respectively. Only 8 genes were also found in the E. coli K12 up-regulated genes. No genes were found in the down-regulated genes clusters between those two strains. For E. coli O157:H7, forty out of the 94 up-regulated genes (43%) were involved in protein synthesis and were highly repressed compared to 40 out of 193 (23%) E. coli K12 up-regulated genes associated with protein synthesis. The wildtype of E.coli O157:H7 colonized two log CFU per root less compared to E. coli K12. Genes involved in biofilm modulation (bhsA and ybiM) were significantly up-regulated in E. coli O157:H7 and curli production (crl and csgA) were found important for E. coli K12 to attach to lettuce roots in the previous studies. BhsA mutant of E. coli O157:H7 was impaired in the colonization of lettuce roots. The SERS spectra of E. coli K12 and O157 controls (cells without interacting with roots) were very similar. The spectra of E. coli K12 and O157 exposed to the hydroponic system (HS) showed some differences in the nucleic acid, protein, and lipid regions compared with controls. The spectra of E. coli K12 HS cells exhibited significant differences compared to spectra from E. coli O157 HS cells in the RNA and protein regions. The overall band intensity of amide regions declined for E. coli O157 HS cells, while it increased for E. coli K12 HS cells. The intensity of the RNA bands of E. coli K12 HS cells were also found much higher than those of E. coli O157 HS cells. These findings were in agreement to our Microarray data. Our microarray and SERS data showed that E. coli K12 and O157:H7 behavior dramatically differently in colonizing on lettuce roots. Compared to K12, E. coli O157:H7 colonized less efficiently on lettuce roots. Escherichia coli O157:H7 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:Opioids such as morphine have many beneficial properties as analgesics, however, opioids may induce multiple adverse gastrointestinal symptoms. We have recently demonstrated that morphine treatment results in significant disruption in gut barrier function leading to increased translocation of gut commensal bacteria. However, it is unclear how opioids modulate the gut homeostasis. By using a mouse model of morphine treatment, we studied effects of morphine treatment on gut microbiome. We characterized phylogenetic profiles of gut microbes, and found a significant shift in the gut microbiome and increase of pathogenic bacteria following morphine treatment when compared to placebo. In the present study, wild type mice (C57BL/6J) were implanted with placebo, morphine pellets subcutaneously. Fecal matter were taken for bacterial 16s rDNA sequencing analysis at day 3 post treatment. A scatter plot based on an unweighted UniFrac distance matrics obtained from the sequences at OTU level with 97% similarity showed a distinct clustering of the community composition between the morphine and placebo treated groups. By using the chao1 index to evaluate alpha diversity (that is diversity within a group) and using unweighted UniFrac distance to evaluate beta diversity (that is diversity between groups, comparing microbial community based on compositional structures), we found that morphine treatment results in a significant decrease in alpha diversity and shift in fecal microbiome at day 3 post treatment compared to placebo treatment. Taxonomical analysis showed that morphine treatment results in a significant increase of potential pathogenic bacteria. Our study shed light on effects of morphine on the gut microbiome, and its role in the gut homeostasis.
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.