Isolamento e potencial probiótico de bactérias do ácido lático e leveduras isoladas de azeitonas de mesa brasileiras

Abstract

Table olives are a fermented product obtained from the fruits of the olive tree (Olea europaea L.), which may contain microorganisms with functional properties. This work evaluated the microbial diversity and physicochemical characteristics of fresh fruits and during the fermentation of Brazilian table olives and selected potentially probiotic microorganisms. Yeasts, mesophilic bacteria and lactic acid bacteria (BAL) were isolated from olives of Grappolo 541 and Ascolano cultivars, protected by the Minas Gerais Agricultural Research Corporation (EPAMIG) and kept in collection at the Maria da Fé Experimental Farm - Minas Gerais- Brazil. The isolates were identified by polyphasic techniques: mass spectrometric analysis, ribosomal protein profile analysis (Maldi-Tof MS) and DNA sequencing. Chemical analyzes were determined by high performance liquid chromatography (HPLC). Twenty species of mesophilic bacteria, seven species of BAL and fourteen species of yeast were identified. Some species, such as Lactobacillus brevis, L. paracasei, Pantoea Agglomerans, Staphylococcus warneri, Candida parapsilosis, C. orthopsilosis, Cryptococcus flavescen, Bacillus simplex and B. thuringiensis, prevailed over others. Glucose and mannitol sugars were the main sugars present in table olives. Acetic, citric and lactic acids were the acids detected at higher concentrations. Of the isolated microorganisms, 14 BAL and 18 yeasts were tested for probiotic potential. Six BAL and six yeasts showed potential properties for use as probiotics: the bacteria Lactobacillus pentosus CCMA 1768; L. paracasei CCMA 1771; L. paracasei CCMA 1774; L. paracasei CCMA 1770; L. brevis CCMA 1766, L. brevis CCMA 1762, and the yeasts Saccharomyces cerevisiae CCMA1746, Pichia guilliermondii CCMA1753, Candida orthopsilosis CCMA1748, C. tropicalis CCMA1751, Meyerozyma caribbica CCMA1758 e Debaryomyces hansenii CCMA1761. These yeasts demonstrated capacity to support conditions like those found in the gastrointestinal tract (low pH, bile salts and temperature of 37 ° C), and exhibited antimicrobial activity against pathogens. Regarding the surface properties, the isolates showed autoaggregation capacity, coaggregation with E. coli and S. Enteritidis pathogen, adhesion to Caco-2 and HT-29 cells. The polyphasic methodology was efficiently performed to identify the microorganisms in this work and the chemical analysis helped to characterize the olives and the fermentation process. These findings are relevant, characterizing previously unexplored Brazilian olives. Knowledge of the native microbiota present in the fruits of these olives and the species involved in fermentation and its evolution along the process can be useful to improve the quality of sensory properties and preservation of this product. In addition, microbiota characterization may result in the isolation of possible biotechnologically important microorganisms. Preliminary in vitro tests indicate the safety and functionality of lactic acid bacteria and yeasts isolated from Brazilian fermented table olives as potential probiotic candidates.