Bactérias ácido lácticas isoladas de silagem de colostro bovino: Potencial probiótico e viabilidade de imobilização celular utilizando como suporte grãos de soja

Abstract

Lactic acid bacteria, with probiotic potential, are considered of great interest for the functional food market, which are expanding due to the contribution of these foods to the health of individuals. The objective of this study was to isolate, characterize lactic acid bacteria with probiotic potential and immobilize them in soybean grains, in order to maintain their viability during storage. Isolation and characterization tests (Gram staining, presence of catalase, technological properties, carbohydrate fermentation) of the isolates were carried out from bovine colostrum silage; Evaluation of microbiological safety parameters (enzyme activity, hemolysin, DNase and gelatinase, susceptibility to antimicrobials of clinical use and plasmid profile), evaluation of probiotic potential (simulation of gastrointestinal transit tolerance, selfaggregation capacity, co-aggregation, Hydrophobicity, β-galactosidase enzyme activity and antagonist activity), evaluation of exopolysaccharide production, molecular identification, cellular immobilization using as support soybean grains and scanning electron microscopy of the biocatalyst. Of the isolates characterized as lactic acid bacteria, six were selected in preliminary tests (technological potential, resistance to different concentrations of bile and fermentation of sugars), three were microbiologically safe and one was characterized as potentially probiotic. The bacterium selected for immobilization, SCL3, belonging to the genus Lactobacillus of the casei species, exopolysaccharide producer, undergoes a fermentative process that allowed the adsorption of cells on the surface of the soybean grains. The immobilization made possible the viability of the cells at a concentration of 6.23 log CFU.g-1 and 6.71 log CFU.g-1 until the end of the 300 day of storage after drying (lyophilization) and in refrigeration, respectively. Scanning electron microscopy allowed the cells to adhere to the surface of the soybean grains.