Potencial biotecnológico de leveduras isoladas de frutas da caatinga fermentadas

Abstract

Fruits are sources of yeast with biotechnological properties on which research has focused on the characteristics they can add to fermented products. Several fruits abundantly produced in the Caatinga Biome have been explored as a source of bioactive compounds, however they have been scarcely explored as a source of yeast with biotechnological potential, or even as matrices for the development of formulations derived from yeast fermentation. The present work aimed to evaluate the biotechnological potential of yeasts isolated from naturally fermented soursop and umbu-cajá. Yeasts were isolated from naturally fermented soursop and umbu-cajá. The isolates were identified via MALDI-TOF and the yeasts Hanseniaspora opuntiae 125, Issatchenkia terricola 129 and Hanseniaspora opuntiae 148 were selected for fermentation of soursop and umbu-cajá pulps based on their identification score and history of application in food. The fermented pulps were characterized regarding physical-chemical aspects (pH, soluble solids, and titratable acidity), sugar profile, organic acids, volatile and phenolic compounds (profile and bioaccessibility). The pulps showed changes in composition when subjected to fermentation by the isolated yeasts and the strains H. opuntiae 125 and I. terricola 129 maintained viability in the soursop sample even after simulated gastrointestinal conditions (≥ 6 log CFU/g). The fermentation of fruit pulps with yeast influenced the quantity and bioaccessibility of phenolics, demonstrating the occurrence of biotransformation of these compounds. In general, fermentation with yeast increased the amount of bioaccessible phenolic compounds, but the increase varied depending on the strain and fruit evaluated. The I. terricola 129 strain was chosen for in vitro tests to modulate the intestinal microbiota of hypertensive middle-aged adults due to the produced effects on the pulp during fermentation and its low ethanol production. The relative abundance of bacterial groups was evaluated using fluorescence in situ hybridization coupled to multiparametric flow cytometry during in vitro colonic fermentation for 48 hours. During fermentation, pH values were measured, and aliquots were taken for analysis of sugars, organic acids, and phenolic compounds. Soursop pulp fermented with I. terricola 129 improved the microbiota by increasing the relative abundance of Lactobacillus spp. and Bifidobacterium spp. and reduce the relative abundance of Eubacterium rectale/Clostridium coccoides and Clostridium histolyticum, resulting in the highest prebiotic index among the products tested. At the same time, the consumption of rhamnose and gallic acid and higher levels of acetic and propionic acids and procyanidin B2 were observed. The results highlight the changes resulting from the fermentation of fruit pulps from the Caatinga with yeasts isolated from fruits and indicate potential benefits of fermented soursop pulp with I. terricola 129 on the colonic microbiota of middle-aged hypertensive adults.