|Liao, Ching Hsing|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: October 5, 2004
Publication Date: January 5, 2005
Citation: Ukuku, D.O., Liao, C., Gembeh, S.V. 2005. Attachment of bacterial human pathogens on fruit and vegetables surfaces. Book Chapter. CRC Press. p. 419-438. Technical Abstract: The ability of pathogenic and spoilage-causing bacteria to adhere to surfaces of fruits and vegetables continues to be a potential food safety problem of great concern to the produce industry. The microbiological safety of fresh and minimally processed fruits and vegetables has been questioned as a result of recent outbreaks of foodborne illness associated with unpasteurized juices, sprouts, melons, lettuce, berries and other commodities. The mechanism of attachment of bacterial cells to plant surfaces has been studied most extensively for plant pathogens and symbionts, but the mechanism of attachment of human bacterial pathogens to produce surfaces is limited. This chapter examines the surface structure (smooth vs rough) of fruits and vegetables in relation to attachment of human bacterial pathogens and the role biochemical characteristics such as surface hydrophobicity and relative surface charge play during attachment onto fruits and vegetables. The chemistry of teichoic acid or polysaccharides on bacterial surfaces confers regions of hydrophobic or hydrophilic properties, which may also function as plant surface adhesins. Bacterial attachment to surfaces is also influenced by cell surface charge, hydrophobicity and also by the presence of particular surface appendages such as flagella, fimbriae and extracellular polysaccharides. Plant surfaces and microbes both have negative surface potential, which results in electrostatic repulsion between the two surfaces. Surface appendages such as pili already present on microbes prior to or induced by the presence of plant surface or other favorable conditions are used to bridge the gap exerted by the electrostatic repulsion. The information presented in this chapter will increase our understanding of bacterial adhesion to fruits and vegetables and therefore may lead to development of more effective washing treatments to control microorganisms on whole produce and fresh-cut pieces.