POTENTIAL OF PREDATORY BACTERIA AS BIOCONTROL AGENTS FOR FOODBORNE AND PLANT PATHOGENS

Foodborne pathogens such as Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes are responsible for frequent occurrences of illness and mortality in humans. Several economically important plant diseases are caused by pathogenic bacteria. Economically important plant diseases and post-harvest losses and decay are also incited by plant pathogens such as Erwinia, Pectobacterium, Botrytis, and Pseudomonas spp. This paper discusses the potential of predatory bacteria for biocontrol of foodborne and plant pathogens with emphasis on the deltaproteobacteria group. Deltaproteobacteria (Bdellovibrio and Bacteriovorax sp. as well as Daptobacter, and Myxobacteria) are Gramnegative predatory microorganisms which prey mainly on Gram-negative bacteria and occur in diverse soil, marine and fresh water ecologies. The predation of Gram-negative bacteria by Bdellovibrio and Bdellovibrio-like organisms (BALOs) may enhance their potential application for biocontrol of foodborne and plant pathogens. The difficulty in controlling foodborne and plant pathogenic bacteria is due to the paucity of available bactericidal chemicals and regulations limiting the use of antibiotics in pathogen control. In this review, the types and mechanisms of predation by predatory bacteria (PB) are discussed with respect to potential utilization as biocontrol agents. Their diversity and relationships is highlighted by genomic research. Potential for biocontrol of foodborne and plant pathogens by PB is discussed in terms of attributes and limitations. Although research in animal systems (Salmonella/chicken) indicates significant biocontrol potential when PB are applied as probiotics, their application to foodborne and plant pathogens are limited. With increased research in metagenomics on PB effects on animal cells /tissues, a better understanding of regulation of cellular metabolism and their association with growth of PB and prey degradation will ultimately enhance the utility of PB as biocontrol agents of foodborne and plant pathogens.