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Food microbiology has historically focused on the study of pathogens or toxin producers causing acute (and sometimes chronic) diseases, spoilage agents affecting food quality, and starter cultures essential for food fermentation or used as probiotics with potential health benefit(s) to the host. Hence, reducing or eliminating pathogenic and spoilage microbes through the farm-to-fork food safety continuum, and improving the performance of starter cultures and probiotics for product quality, specific health benefit(s) and industrial financial assurance, have been the main themes for the food microbiology research for years. However, it has become increasingly apparent that these organisms account for only a small proportion of the microflora associated with foods; diverse microbial species within the environment, foods, and the host interact with one another in ways that are only beginning to be elucidated. For instance, on a daily basis, humans can easily consume 10*10 CFU microorganisms, with up to 10*6 CFU harboring some sort of antibiotic resistance. The vast majority of these organisms are commensal rather than pathogenic. Some of the fermentation starter cultures and even probiotic strains can become carriers of the resistance genes. These organisms have ample opportunity to shape the host ecosystem by interacting with the existing host microflora through various forms of signal exchange, serving as donors for horizontal gene transfer, or becoming part of the host ecosystem, and their impact on the general health of the public and the importance in disease progression are yet to be revealed. <P>
Our objective for this proposed 6-year study is to continue investigating the microbial ecology associated with the food chain and to reveal the importance of microbial progression to food safety and quality, as well as the contribution of commensal organisms to ecosystem development, disease progression, and resistance to antimicrobial agents.
NON-TECHNICAL SUMMARY: The rapid emergence of antibiotic resistant pathogens threats public health and causes significant financial loss to the society. The food chain serves as the most important avenue introducing microorganisms including antibiotic resistant bacteria to human through daily food intake. The purpose of the proposed study is to investigate both the total microbial flora and antibiotic resistant microbial population in foods and the molecular mechanisms involved in horizontal gene transmission and microbial ecosystem development. Results from the study are essential for the development of counter strategies to combat this major challenge in food safety and public health. <P>
APPROACH: We will development a rapid, high throughput detection platform to identify and quantify microorganisms in complex ecosystems such as samples collected from dairy production and processing environments and to investigate the roles of horizontal gene transfer-susceptible foodborne commensal bacteria in transmitting antibiotic resistance genes from the environment to the host. We will continue investigating molecular mechanisms involved in biofilm formation and ecosystem development and the microbial interactions with food matrices, microbes and hosts within such ecosystems involving the fermentation starter culture lactic acid bacteria, the spoilage agent Pseudomonas spp., and the pathogen Listeria monocytogenes. Results from this proposed study will likely generate novel understandings regarding the roles of foodborne microbes on food safety and public health and lead to changes in food industry practices.