Avaliação do potencial probiótico e tecnológico de bactérias láticas isoladas de queijo minas artesanal da região da Canastra

Abstract

To be considered a probiotic, a live microorganism, when administered in adequate amounts, must confer some benefit on the individual's health. These microorganisms belong to different genera and species, both bacteria and yeast, and have been associated with several beneficial effects. Lactic acid bacteria (LAB) can be found in various food matrices, such as dairy products, meat, as well as products of plant origin (indigenous fermented beverages and cocoa). The endogenous microbiota of Minas Artesanal Cheese (QMA) confers typical organoleptic characteristics, composed mainly of lactic acid bacteria and yeasts present in the milk, in the processing environment and mainly in the “pingo. The selection of probiotic microorganisms from artisanal cheeses is of scientific and industrial interest, due to the biotechnological and functional potential to be explored. In this context, the objective of the present study was to isolate, identify and evaluate the technological and probiotic properties of BAL isolated from QMA from the region of Canastra-MG. To this end, LAB isolation and identification was performed by proteomic analysis, followed by probiotic potential tests through analyzes of antimicrobial activity against pathogenic microorganisms, susceptibility to antibiotics and survival in the simulated gastrointestinal tract. Subsequently, tests of technological potential were performed through the analysis of proteolytic and lipolytic activity of the isolates. The species Lactobacillus plantarum was identified in 40% of the isolates. Among the others, 15 were identified only at the genus level, Lactobacillus spp. (33%) and the remainder (26%) did not result in reliable identification. As for antimicrobial activity, the species L. plantarum LP116, L. plantarum LP77, L. plantarum LP24 and L. plantarum LP48, showed inhibitory activity against all pathogens evaluated (Staphylococcus aureus, Listeria. monocytogenes, enteropathogenic Escherichia coli (EPEC) and enterotoxigenic E. coli (ETEC)). The isolates that showed the best results of antimicrobial activity were selected for the gastrointestinal tract simulation assay. Only the isolate L. plantarum LP24 showed a moderate survival rate (59.26%). When evaluating susceptibility to antibiotics, all isolates evaluated were sensitive to at least one antibiotic of the protein synthesis inhibitor and cell wall classes. All isolates were sensitive to erythromycin and ampicillin, and resistant to vancomycin, norfloxacin and chloramphenicol. As for the technological potential, all tested isolates showed some proteolytic activity; where, the isolates L. plantarum LP94 and LP24, and Lactobacillus spp. L105 and L88 resulted in the greatest ability to degrade milk casein. Of the isolates evaluated for lipolytic activity, the isolates L. plantarum LP48 and LP94 and Lactobacillus spp. L41 resulted in moderate activity. Among the isolates, L. plantarum LP24 exhibited interesting probiotic and technological properties, making it the most promising candidate in the present study. The Lactobacillus genus is one of the most evaluated regarding technological characteristics in Brazilian artisanal cheeses and is widely used as a starter culture for the manufacture of a range of fermented products. This study shows how the QMA from the Canastra region can constitute a good reservoir for new strains of LAB for industry.