Functional Properties of Plasmids as Related to Enumeration of Bacteria Important to the Food Microbiologist

Journal of Food Protection
Clifford Howell, William J Martin

Abstract

Plasmids are extrachromosomal elements that behave like auxiliary chromosomes and contain the basic structure of the replicating unit. They were initially recognized by the unusual phenotypic characteristics they confer upon a cell, such as ability to promote genetic transfer by conjugation; resistance to antibiotics and metal ions; production of bacteriocins, toxins, antigens; and other factors. Much of the work on plasmids and plasmid-mediated characteristics has been conducted with various genera and species of the family Enterobacteriaceae . Present data indicate that although plasmid transfer occurs with variable frequency, intergeneric transfer within the family is invariably successful. Although a great deal of investigation has been focused on plasmid-mediated resistance to antibiotics, many workers have determined that a number of plasmids control other phenotypic characters. For example such plasmids appear to mediate production of bacterial products and/or enzymes which may confer a selective ecological advantage to bacteria in their inter-relationships with their hosts and other microorganisms. The isolation of these phenotypically altered microorganisms by food, medical, and public health microbiologists may signif...Continue Reading

Citations

Feb 1, 1979·Journal of Dairy Science·R A Ledford, J M Brown

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