Abstract

ORTIZ, Silvia G et al. Effect of bioprotective lactic cultures on the growth of food-borne pathogenic microorganisms at low temperatures. Rev. cienc. tecnol. [online]. 2014, n.21, pp.27-32. ISSN 1851-7587.

Increasing demand for minimally processed vegetables brought about a higher incidence of outbreaks of foodborne illnesses associated with their intake. Lactic acid bacteria may limit the development of pathogens in these foods during cold storage. The objective of this work was to evaluate the effect of lactic acid bacteria isolated from minimally processed vegetables on the growth of pathogenic and indicator bacteria in a model system at low temperatures. Listeria monocytogenes, Salmonella Enteritidis and E. coli were inoculated into tryptone soy broth (concentration: 104 cfu / ml) in coculture with native lactic acid bacteria strains, and incubated for 4 days at temperatures between 5 and 15 °C. Periodically, bacteria survivors were determined by the plate-count technique. Control treatments of L. monocytogenes (without lactic cultures added) showed only lag phase at 5 °C, and reached the stationary growth phase at 15 °C - 48 h. With lactic cultures added, L. monocytogenes showed a longer lag phase, a slower growth rate and did not reach the stationary-phase during the 4 days of incubation. S. Enteritidis remained stable at 5 °C, without significant difference between control and treatments in coculture with lactic bacteria. In contrast, at 15 °C S. Enteritidis showed slower growth rate in coculture with lactic acid bacteria. E. coli showed no significant differences between treatments in control and co-culture with lactic acid bacteria. In conclusion, the native lactic cultures could function as an additional barrier to limit the growth of pathogens in food at low temperatures, without affecting the growth of indicators.

Keywords : Bioprotection; Lactic acid bacteria; Listeria monocytogenes; Salmonella Enteritidis; Escherichia coli.

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