Caracterização do potencial probiótico e tecnológico de cepas de lactobacillus isoladas de subprodutos do processamento de frutas

Abstract

A variety of human health benefits have been related with the use of probiotic microorganisms, which are represented mainly by lactic bacteria but primarily by species belonging to the Lactobacillus genus. Fruit processing byproducts has been known as potential sources of Lactobacillus; however, studies on the probiotic properties of Lactobacillus strains isolated from these materials are still scarce. In this context, this study examined nine Lactobacillus strains (L. plantarum 53, L. fermentum 56, L. fermentum 60, L. paracasei 106, L. fermentum 250, L. fermentum 263, L. fermentum 139, L. fermentum 141 and L. fermentum 296) isolated from fruit processing for a series of safety (e.g., antibiotic susceptibility, haemolytic activity and mucin degradation), physiological functionalities (e.g., acid and bile salts tolerance, bile salts desconjugation, cell surface hydrophobicity, autoaggregation, coaggregation with pathogens, antagonistic activity against pathogens and capability of surviving during exposure to simulated gastrointestinal conditions), and technological properties (e.g., proteolytic and lipolytic activity, tolerance to NaCl, exopolysaccharide and diacetyl production), that could enable their use as probiotics. Considering the safety aspects, the resistance to antibiotics varied among the examined strains, and none of the strains presented hemolytic and mucinolytic activity. Regarding the physiological functionality properties, none of the strains was able to deconjugate bile salts; all of them presented low to moderate cell hydrophobicity, were able to autoaggregate, coaggregate with Listeria monocytogenes and Escherichia coli and antagonize pathogenic bacteria. The exposure to pH 2 sharply decreased the survival of the examined strains after 1 or 2 h-exposure; variable decreases were noted after 3 h-exposure to pH 3. Overall, the exposure to pH 5 and to bile salts (0.15, 0.3 and 1%) did not decrease the survival of the examined strains. The examined strains presented better ability to survive the exposure to simulated gastrointestinal conditions in laboratorial media and milk than in grape juice. Considering the technological properties, all the strains were positive for proteolytic activity, EPS and diacetyl production, and most of them had good tolerance to 1 - 4% NaCl. Overall, L. fermentum 139, L. fermentum 263 and L. fermentum 296 showed the best performance for most of the evaluated properties. These results indicate that wild Lactobacillus strains isolated from fruit processing byproducts could be candidates for use as new probiotics.