Enhancing microbiological safety of water and food
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Human and animal feces are the main sources of pathogens associated with foodborne and waterborne disease outbreaks. The studies in Volume I proposed ribosomal intervening sequences (IVSs) can be used as host-specific genetic markers for tracking fecal sources in polluted food and water. In Chapter 3, using bioinformatics tools, one IVS in Faecalibacterium 16S rDNA specific to poultry (chicken and turkey) was identified in silico. A PCR assay was then developed to confirm the IVS was only present in fecal or wastewater samples from poultry. The study in Chapter 4 comprehensively examined host specificities of IVSs in 16S rDNA of 73 genera of fecal bacteria. A total of 13 IVSs were identified to be associated particular host sources in silico and the host-specificities of eight of them were confirmed by PCR reactions. Furthermore, a novel beef cattle-specific IVS was identified with next generation sequencing (NGS). Internalization of human pathogens in produce poses high risks to human health because the surface-sanitization method fail to inactivate the pathogens. The study in Volume II proposed to control the pathogen internalization with endophytic Bacillus subtilis strains isolated from vegetables. Twelve endophytic B. subtilis strains isolated from inner tissue of lettuce stems and mung bean seeds displayed inhibitory activity against a Salmonella enterica indicator in vitro and two of them (LCA1 and M24) showed broad inhibitory spectrums. LCA1, M24, and a laboratory strain B. subtilis 168 could internalize in mung bean sprouts and significantly reduced the internalization of S. enterica and enterohaemorrhagic Escherichia coli (EHEC).
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