Interactions of Food Starter Cultures and Food-Borne Pathogens: Streptococcus Diacetilactis Versus Food Pathogens1,2

Abstract

The ability of Streptococcus diacetilactis to inhibit a variety of food spoilage organisms and pathogens in milk and broth cultures was demonstrated. Test organisms included Pseudomonas and Alcaligenes species, Salmonella, Staphylococcus aureus, Clostridium perfringens, and Vibrio parahaemolyticus. In general, approximately 99.0% and 99.9% inhibition was observed in milk and broth, respectively. Possible practical applications of the inhibition were examined. Addition of S. diacetilactis extended the shelf life of artificially contaminated cottage cheese and prevented proteolysis in milk at 7.5 C by Pseudomonas fluorescens. Staphylococcus aureus was inhibited greater than 99% in vanilla cream filling, ham sandwich spread, chicken gravy, soy milk, and ground beef stored at 25 C for 24 hr. Development of the gram-negative flora of ground beef was also inhibited greater than 99% after storage at 7.5 C for 7 days. Possible roles for several factors in the mechanism of inhibition by S. diacetilactis are briefly discussed. The effects of pH reached and acids produced by S. diacetilactis on the growth of S. aureus are described. A greater role for the lactic acid bacteria in fermentations in the food industry is suggested.

Unveiling Staphylococcus aureus enterotoxin production in dairy products: a review of recent advances to face new challenges

“…Still unidentified mechanism(s) acting jointly with acidification has (have) often been suspected (Charlier et al 2008;Daly et al 1972;Gilliland and Speck 1974). Recently, a mathematical model of the interaction between S. aureus and LAB highlighted that the critical parameter was not pH or lactic acid production but more likely a critical density of the LAB population itself (Le Marc et al 2009).…”

Characteristics of the bacteriocin produced by Lactococcus lactis subsp. cremoris CTC 204 and the effect of this compound on the mesophilic bacteria associated with raw beef

“…lactis biovar. diacetylactis have been used to inhibit the growth of gram-negative bacterial populations in refrigerated ground beef (Daly et al 1972). Meat stored in air is rapidly spoiled by bacteria, which are responsible for discoloration and production of off-odours, resulting in consumer rejection (Labadie 1999).…”

Preservation and fermentation: past, present and future

“…Indeed, there are many examples which report the inhibition of spoilage and pathogenic bacteria by LAB (Kao and Frazier;1966;Price and Lee, 1970;Klaenhammer, 1988;Holzapfel et al, 1995). In a study by Daly et al (1970), the foodborne pathogens Pseudomonas fluorescens, Staphylococcus aureus and Clostridium perfringens were inhibited when co-cultured with a Streptococcus diacetylactis strain. In this case, the S. aureus numbers were reduced by more than 99% in foods such as ham sandwich spread, chicken gravy and ground beef.…”