Meat Native Lactic Acid Bacteria Capable to Inhibit <i>Salmonella</i> sp. and <i>Escherichia coli</i>

Abstract

Salmonella and E. coli are the most important genera in meat (Devlieghere et al., 2004) . Salmonella is related with 93.8 million of worldwide human infection cases, and 155,000 annually deaths (Majowicz et al., 2010) . In the Salmonella infections outbreaks, beef is the most commonly implicated food (Jackson, 2014) . In the same way, E. coli is the most frequent bacteria isolated from meat and its used as indicator of fecal contamination, their pathogenic serotypes (enterohemorrhagic, enteropathogenic, diarrheagenic and verotoxigenic) are responsible for multiple outbreaks of food-borne diseases throughout the world (Hiko et al., 2008) , only in USA is attributed about 40,000 annually deaths, and ground beef is commonly food vector (Russo and Johnson 2003) .The natural microbiota (NM) of meat is a complex ecosystem involving several types of microorganisms, including some LAB populations with inhibitory capacity.Over time, the use of LAB to preserve meat has been proposed, however, most of the suggest bacteria are from fermented products or ATCC strains. Therefore, the objective of this work was to isolate meat native LAB strains from ground beef with antagonistic capacity against two reference bacteria (Salmonella and E. coli) and estimate the inhibition effect of LAB cultures and their CFS, using in vitro techniques. Fifty samples of raw ground beef were aseptically obtained according to Official Mexican Standard No. 109, from butchers and meat retailers in Texcoco de Mora, Mexico, and which were transported and storage (-20 °C) in the laboratory of Livestock Microbiology, Chapingo Autonomous University. Aliquots (25 g) of each sample were placed on sterile bottles and homogenized with peptone solution (225 mL, Bioxon) in a blender for 1 min. Serial dilutions were made with sodium chloride solution 0.85% w/v (saline) and pouring (200 µL) in de Man, Rogosa and Sharpe (MRS, Dibico) agar and incubated 48 h at 37 °C. LAB characteristic colonies were taken and isolated by streaking in MRS agar. All bacteria strains were stored in appropriate media with glycerol (30%) at -20 °C.