Identificação e avaliação do potencial probiótico de leveduras isoladas de frutos amazônicos para aplicação em alimentos

Abstract

Probiotics are considered microorganisms that, when ingested in sufficient and adequate amounts, can result in several benefits to the health of the host. Among the microorganisms that have this potential, yeasts have gained prominence in terms of their probiotic application, and among the genera, the yeast Saccharomyces boulardii is the best known and commercially available as a probiotic. Bacupari (Garcinia gardneriana), tucumã (Astrocaryum aculeatum) and pupunha (Bactris gasipaes Kunth), are fruits native to the Amazon region, rich in fiber, lipids and carotenoids; appreciated mainly by the population of the North of the country and have great biotechnological potential. Thus, the present research identified and evaluated the probiotic potential of yeasts isolated from native fruits of the Amazon region for later application in the food industry. 418 yeasts previously isolated from the aforementioned fruits were reactivated, of which 321 were viable, followed for morphological analysis and growth tests at 37°C, ability to survive an acidic environment (pH 1-2, pepsin 3 g/L and NaCl 5 g/L), resistance to fluconazole and amphotericin B antifungals, and antagonistic activity against the following pathogens: Salmonella enterica subsp. enterica serovar Typhimurium (ATCC 14028), Escherichia coli (CDC EDL 1284-ATCC 43893), Shigella sonnei (ATCC 11060) and Staphylococcus aureus (ATCC 25923). Bile salt tolerance tests (0.3%), self-aggregation and coaggregation capacity, virulence factors (lipase, gelatinase, DNAse and hemolytic activity) and preservation in the form of lyophilization were performed. The results obtained show that of the 321 yeasts submitted to the growth test at mammalian body temperature (37°C) 288 showed growth, of which 213 were able to grow in simulated conditions of stomach acidity. Of the 57 yeasts that were sensitive to amphotericin B, 12 showed antagonistic activity against the tested pathogens. In addition, all 12 yeasts tested in the presence of 0.3% oxgall showed viability, however, in the self-aggregation and coaggregation tests, only three yeasts were selected, which were submitted to virulence factor tests and demonstrated to be able to follow for lyophilization using three cryoprotectants. The results obtained during the lyophilization process indicate that the yeast LTC 13 presented the best results, and, among the cryoprotectants used, glucose 10% presented the best performance during the process. As for molecular identification, the three yeasts belong to the following species: Meyerozyma carpophila, Meyerozyma guilliermondii and Rhodotorula mucilaginosa.