Grape marcs as unexplored source of new yeasts for future biotechnological applications.

In recent years the potential of using microbes as biotechnological sources of industrially relevant enzymes has stimulated a renewed interest in the exploration of new unconventional habitats like trove of natural biodiversity. In this work, grape marcs was selected as extreme environment because of its limited nutrients, exposure to solar radiation, temperature fluctuations and ethanol. One hundred and eighty non-Saccharomyces yeasts and two hundred and twenty Saccharomyces cerevisiae strains were screened for the production of extracellular amylases, cellulases, lipases, pectinases, proteases and xylanases. Two non-Saccharomyces strains were found effective for the hydrolysis of cellulose and starch while eleven S. cerevisiae isolates were described as proficient pectinase producers. For the first time, thirteen S. cerevisiae strains, potentially able to use starch as the sole carbon source, were reported and their potential amylolytic phenotype was found to be related to a non extracellular alpha-amylase. This study encourages the selection of yeasts isolated from grape marcs as sources of unusual and industrially interesting enzymes for future biotechnological applications.