Fungi isolated from olive ecosystems and screening of their potential biotechnological use

This study investigated the fungi diversity of fresh olive (Olea europaea L.) fruits, olive paste (crushed olives) and olive pomace (solid waste) and screened and quantified enzymatic activities with biotechnological applications. Fungi were randomly isolated from olive cultivars from Castilla La Mancha region (Spain). Identification included comparison of their polymerase chain reaction (PCR) amplicons of the ITS1-5.8S-ITS2 ribosomal DNA region, followed by nucleotide sequence analysis. Fourteen different species with DNA sequences of different similarities were identified, belonging to seven different genera (Aspergillus, Penicillium, Rhizomucor, Mucor, Rhizopus, Lichtheimia and Galactomyces). Aspergillus fumigatus, followed by Galactomyces geotrichum, Penicillium commune and Rhizomucor variabilis var. regularior were the most frequent species. Specific enzyme screening was assayed on agar plates, using cellobiose, carboxymethylcellulose (CMC), polygalacturonic acid and CaCl2/Tween 80 as substrates for beta-glucosidase, carboxymethylcellulase (CMCase), polygalacturonase and lipase, respectively. Species exhibiting the best activities were: Aspergillus fumigatus (for beta-glucosidase, CMCase and lipase); Rhizopus oryzae (for beta-glucosidase and lipase); Rhizomucor variabilis (for beta-glucosidase, CMCase and polygalacturonase); Mucor fragilis (beta-glucosidase, CMCase and lipase); Galactomyces geotrichum (for beta-glucosidase, polygalacturonase and lipase) and Penicillium commune and Penicillium crustosum (for lipase). The species that had shown the best enzymatic activities were grown on hemicellulose, cellulose and pectin and some activities were quantified (xylanase, cellulase, beta-glucosidase and pectinase). An isolate of A. fumigatus and one of A. niger showed the best cellulase and xylanase activities, while no species presented good pectinase and beta-glucosidase activities. The selected species with potential enzymatic activities could be used for future applications of industrial interest.