Potencial probiótico in vitro de Lactobacillus spp. isolados de queijo Minas artesanal da Serra do Salitre-MG

Abstract

The traditional artisanal Minas cheese is characterized by the use of raw milk and endogenous starter culture in its elaboration. The typical flavor of these cheeses is obtained by transformations performed mainly by lactic acid bacteria (LAB) present in milk, endogenous starter culture and cheesemaking environment. In addition, some of these bacteria can inhibit the growth of undesirable microorganisms and are able to tolerate gastrointestinal tract stress conditions, being considerated probiotics. The objective in this study was to submit species of Lactobacillus spp. isolated from artisanal Minas cheese from Serra do Salitre (MG) to in vitro tests of antagonism against pathogenic microorganisms and LAB from the cheese, antimicrobial susceptibility and tolerance to artificial acid and bile salts in order to select potential probiotics in vitro. The proteomic identification was performed and six samples belonging to the species L. paracasei (C1 e C2), L. plantarum (L1 e L2) and L. rhamnosus (R1 e R2) were selected for the experiment. All the samples presented antagonism activity against the pathogens Escherichia coli, Staphylococcus aureus, Shiguella flexneri and Salmonella enterica serovar Typhimurium, being E. coli and S. aureus the most inhibited and the inhibitory action among Lactobacillus spp. was discreet or absent. The samples L. plantarum (L1 e L2) and L. rhamnosus (R1) were considered tolerant to gastric acid (pH 2.0) and L. paracasei (C2) and L. plantarum (L1) were considered tolerant to the presence of Oxgall (0,3%). All samples were resistant to cefoxitin and vancomycin and sensitive to amoxicillin, ampicilin, chloramphenicol and tetracycline. The results of the antagonism test indicate that the studied samples could aid in the control of pathogens in cheeses. The sample L1 presented the best probiotic potential due to tolerance to acid and bile salts and can be sunmitted to in vivo tests to ensure this potential. The resistance to antibacterial resistance detected in this research points to the need to study the ability to transfer antibiotic resistance genes that determine this phenotype.