MOLECULAR BIOLOGY OF HUMAN PATHOGENS ASSOCIATED WITH FOOD
Location: Produce Safety and Microbiology Research
Title: Bactericidal activities of health-promoting,food-derived powders against the foodborne pathogens Escherichia coli,listeria monocytogenes, salmonella enterica,and staphylococcus aureus
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 19, 2012
Publication Date: N/A
Interpretive Summary: Food-derived products, such as neutraceuticals, are a good source of bioactive compounds that might protect against pathogens in foods. In addition to being readily available, some of these formulations are prepared from agricultural waste products, e.g. olive pomace from olive oil production and grape seeds from wine production, which could provide both ecological and economic advantages. The present study describes the relative antimicrobial activities of selected food-based 'health food' powders and some of their bioactive constituents against four major foodborne pathogens, Escherichia coli, Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus. Olive and oregano derived products were active against all four pathogens and can therefore be considered to act as broad-spectrum antibiotics that merit further evaluation for their potential to inhibit these pathogens in human foods and animal feeds for the benefit of microbial food safety and animal and human health. The very high activities of nearly all evaluated substances against Staphylococcus aureus are of particular interest. Testing of the most active powders should be extended to the pervasive antibiotic-resistant S. aureus strains.
We evaluated the relative bactericidal activities of 10 presumed health-promoting food-based powders (nutraceuticals) and for comparison, several selected known components of such powders against the following foodborne pathogens: Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus. The relative activities were evaluated using quantitative bactericidal activity (BA50 value is defined as the percentage of the sample in the assay mixture that resulted in a 50% decrease in colony-forming-units (CFUs)). The BA50 values were determined with a statistical regression program using concentration-antimicrobial response data. The lower the BA50 value and the greater the value of 1/BA50, the greater the activity. Olive pomace, olive powder, and oregano leaves were active against all four pathogens, suggesting that they behave as broad-spectrum antibiotics. All powders exhibited strong antimicrobial activity against S. aureus. The following powders showed exceptionally high activity against S. aureus (as indicated by the low BA50 values shown in parentheses): apple skin extract (0.002%), olive pomace (0.008%), and grape seed extract (0.016%). Listeria bacteria were also highly susceptible to apple skin extract (0.007%). The most active substances provide candidates for the evaluation of antimicrobial effectiveness in human food and animal feed.