Progress 10/01/12 to 09/30/13
Outputs
Progress Report Objectives (from AD-416): Identify the molecular mechanisms that underlie the interaction of enteric pathogens with fresh-cut leafy vegetables. Approach (from AD-416): Transcriptomics in Salmonella and pathogenic E. coli; bacterial population dynamics on fresh-cut lettuce and spinach; and use of lettuce lines and Arabidopsis mutants that are defective in specific basal defense signaling pathways. Documents Reimbursable with National Center for Food Safety and Technology (AFRI).Log 42224. Formerly 5325-42000-044- 10R 05/05/11 Using RNAseq technology, ARS scientists at Albany, California, have characterized the gene expression profile of E. coli O157:H7 in lettuce under modified atmosphere packaging conditions, and identified several genes that have a role in the tolerance of the pathogen to various stresses resulting from lettuce shredding and packaging under low oxygen tension. This research relates to Objective 1: Identify and characterize the microbial genes that are involved in the attachment, colonization and survival of enteric pathogens on produce, and Objective 2: Determine the genetic and biochemical factors in plants that effect the attachment, growth and survival of human pathogens in/on plants. The study pertains to NP108 Problem Statement 1B Systems Biology and addresses the need to understand, utilizing �omics�, the effect of environmental conditions (in this case, MAP fresh-cut lettuce) on human pathogens, and determine how the pathogen may in turn influence conditions in that environment.
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): Identify the molecular mechanisms that underlie the interaction of enteric pathogens with fresh-cut leafy vegetables. Approach (from AD-416): Transcriptomics in Salmonella and pathogenic E. coli; bacterial population dynamics on fresh-cut lettuce and spinach; and use of lettuce lines and Arabidopsis mutants that are defective in specific basal defense signaling pathways. Documents Reimbursable with National Center for Food Safety and Technology (AFRI).Log 42224. ARS scientists at Albany, CA, have developed a method to perform gene expression profiling by RNAseq to investigate the physiology of E. coli O157:H7 in packaged processed lettuce. Also, parental and mutant lines of the model plant Arabidopsis thaliana were used to identify basal plant defense pathways that have a role in E. coli O157:H7 colonization of wounded leaf tissue, such as is resulting from the fresh-cut processing of lettuce. This research pertains to NP108 Problem Statement 1B, Systems Biology, and addresses the need to understand, utilizing �omics�, the effect of environmental conditions (in this case, MAP fresh-cut lettuce) on human pathogens, and determine how the pathogen may in turn influence conditions in that environment. Monitoring of activities was done through meetings at conferences on produce safety and microbiology, conference calls, and emails.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Identify the molecular mechanisms that underlie the interaction of enteric pathogens with fresh-cut leafy vegetables. Approach (from AD-416) Transcriptomics in Salmonella and pathogenic E. coli; bacterial population dynamics on fresh-cut lettuce and spinach; and use of lettuce lines and Arabidopsis mutants that are defective in specific basal defense signaling pathways. Studies under this project at the USDA have not fully begun yet because a technician to carry out the studies has not been hired due to a government freeze on hiring in the spring. The freeze has now been lifted. However, samples of shredded inoculated and uninoculated Romaine lettuce incubated for various time periods have been prepared and plant RNA was extracted for quantitative polymerase chain reacions (QRT-PCR). The PI at the Illinois Institute of Technology has constructed mutants of Salmonella in order to test for survival on processed lettuce. The Pinciple Investigator(PI) at IIT and the Co-PIs at ARS have been communicating via email.
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