EVALUATION OF THE INTERACTION OF LYOPHILIZED STRAINS Lactobacillus spp. ISOLATED FROM PIG AGAINST Escherichia coli O157:H7

RUIZ MJ; PADOLA NL; GARCÍA M; INDART, M; ETCHEVERRÍA AI

San Miguel de Tucumán

Simposio; V Simposio Internacional de Bacterias Lácticas - Instituto CERELA V INTERNATIONAL SYMPOSIUM ON LACTIC ACID BACTERIA BENEFITTING FROM LACTIC ACID BACTERIA PROGRESS IN HEALTH AND FOOD; 2016

CERELA

EVALUATION OF THE INTERACTION OF LYOPHILIZED STRAINS Lactobacillus spp. ISOLATED FROM PIG AGAINST Escherichia coli O157:H7.MJ Ruiz, M Indart, M García, NL Padola, AI EtcheverríaFacultad de Cs Veterinarias, CIVETAN, CONICET, Universidad Nacional del Centro de la Pcia. de Bs As. Campus universitario Arroyo Seco s/n. B7000, Tandil, Bs. As. Argentina. E_mail: jruiz@vet.unicen.edu.ar The genus Lactobacillus daily generates a growing interest between microbiologists and technologists to discover new biotechnological applications and probiotic properties. Typically, the strains used for the development of probiotics or food preservation, are isolated from humans. However, studies have shown that animal strains also have beneficial effect on the human organism and inhibitory activity against pathogenic microorganisms. This antagonistic capacity has generated interest in the food industry for the potential biopreservation of their products. The antibacterial activity has been attributed to a heterogeneous group of peptide type substances, organic acids, hydrogen peroxide, free radicals, diacetyl, acetaldehyde, D isomers of amino acids, antibiotics and bacteriocins. By a method as lyophilization, it is possible to concentrate the protein with inhibitory activity produced by these strains, which facilitates the handling both in the laboratory and in the food industry. The aim of this study was to evaluate the ability of interaction between two strains of Lactobacillus spp. lyophilized porcine against Escherichia coli O157:H7. In developing this study eight strains were used Lactobacilllus spp. molecularly identified by PCR and inhibitory activity against Escherichia coli O157:H7 EDL933. The Lactobacillus spp. were cultured on ridges at a perpendicular angle of the plates of MRS, making all possible combinations among the eight strains. The plates were incubated at 37°C in microaerophilic for 24 h, were inactivated with chloroform vapors for 20 min and were aerated for another 10 min. Moreover, a suspension of EDL933 with an optical density of 3x108 CFU/ml was spread with a swab in several directions in the space between the two grooves of Lactobacillus spp. The plates were incubated aerobically at 37°C. It was observed that the interaction between strains 2, 3, 4, 5, 6, 7 and 8 showed synergism, meaning that the pathogen growth zone of inhibition -which spread the two strains or inhibitory metabolites-, is greater than the inhibition of bacterial growth strains where they act independently. Strain 1 showed antagonism with other strains, since the formation of a wedge of bacterial growth in the diffusion zone was observed. Therefore no indifference was observed between them because halos of inhibition in combination were not the same as halos independently. It can be concluded that there is a positive relationship, synergistic, between most of the strains tested. This suggests that the application of these strains of Lactobacillus spp. in the food industry as potential biopreservadores agents, present an interesting alternative to improve the microbiological quality of food.