Isolamento de leveduras de cavernas e avaliação do seu potencial biotecnológico para fermentar hidrolisados lignocelulósicos

Abstract

This work aimed to isolate, identify, and perform a biotechnological evaluation of yeasts isolated from 15 caves located in the state of Minas Gerais. For this purpose, soil samples from different areas of the caves were used, and for isolation, a plating was carried out using Malte Extract medium. Yeast identification was performed through MALDI-TOF. The yeast biotechnological potential was evaluated through their xylitol, ethanol, protein, and biomass production by performing xylose and coffee lignocellulosic hydrolysates fermentation tests. Ethanol and protein production was evaluated by HPLC and the Kjeldahl method, respectively. Biomass production was calculated using a calibration curve. A total of 236 yeasts were isolated and identified by MALDI-TOF, among the isolates there were species that were not reported in the literature found in caves. During the biotechnological evaluation no strain produced xylitol and a few strains produced ethanol. Regarding protein production, a strain identified as C. orthopsilosis presented the highest protein percentage with 35.8%. The results obtained showed that caves are not completely isolated environments from the external environment. The structure of the cave, its interaction with the external environment, and changes in the surrounding environment influences the entry of organic matter at the cave. Furthermore, this is the first work in which the yeasts biotechnological potential from caves is evaluated. The results demonstrated key parameters for ethanol, protein and biomass production of yeasts in lignocellulosic hydrolysates for future works.