Food Biotechnology Potential of Grape-Derived Aureobasidium pullulans: Characterization and Screening for Enzyme Production Capacity

Abstract

Aureobasidium pullulans is a polyextremotolerant yeast-like fungus increasingly recognized for its role in food ecosystems and its emerging potential in flavour development and nutrient modulation. However, systematic evaluations of autochthonous grape-associated populations integrating technological performance and safety-related traits remain limited. This study provides a broad phenotypic screening of 70 isolates from Maraština grapes (Dalmatia, Croatia), applying an integrated functional screening approach to link enzymatic potential, environmental resilience, and food safety. Most isolates displayed multiple hydrolytic enzymes, with widespread cellulase, pectinase, xylanase, esterase, and protease activities. Several isolates showed very high enzymatic indices, supporting their potential for plant-derived substrate transformation, aroma release, and food processing applications. β-glucosidase and urease activities were common, while amylase was limited. Ecological screening confirmed robust adaptability to salinity, osmotic stress, and wide pH ranges. Notably, 31% of isolates demonstrated phosphate solubilization capacity, indicating a possible contribution to mineral bioavailability and nutritional enhancement. Safety screening revealed decarboxylation of selected amino acids, while two isolates lacked detectable activity, highlighting them as candidates for further safety evaluation. Overall, this work establishes a framework for selecting A. pullulans isolates for next-generation, flavour-oriented and nutritionally enhanced food applications, supporting sustainable bioprocessing and future industrial validation.