Degradazione di bioplastiche da parte di ceppi fungini isolati da un impianto di compostaggio

The work of this thesis, carried out at Mycotheca Universitatis Taurinensis (MUT), is focused on the identification of fungal strains able to degrade a specific bioplastic bag for domestical organic waste collection. The attention was aimed on testing a varied fungal biodiversity belonging to several species in order to identify strain-specific characteristics for the bioplastic degradation. The purpose of this work was to detect the most performing fungi able to use that specific bioplastic as a source of sustenance, in order to send promising strains to other composting plats to prove their capabilities on degrading bioplastics in real contests out of laboratory. The thesis is introduced with an excursus on the plastic role in society, its influence on environment, on the role and the characteristics of bioplastics and their ways to be degraded. Seventy-two fungal strains preserved at Mycotheca Universitatis Taurinensis (MUT, the fungal collection of the University of Turin) have been isolated from a composting plant and they were identified by combining molecular and morphological traits. A primary solid screening was carried out to select fungal strains capable of growing in the presence of bioplastic as sole carbon source. The variations in the polymer structure due to bioplastic biodegradation were determined with a qualitative method, using sterilized tweezers. Most of the fungal community have been identified as belonging to the genera Aspergillus and Penicillium. Most of the fungal strains tested negative (81%), therefore, were unable to affect the bioplastic. The remaining fungal strains were identified as positive (13%) or partially positive (6%) in the bioplastic degradation test. Between the positive fungi for solid bioplastic screening there were Cladosporium, Aspergillus, Alternaria, Dydimella and Penicillium genera. It was noted that among the isolated strains the Cladosporium seemed more suitable for the degradation of bioplastic. Consulting the literature, that show that Penicillium and Aspergillus are the most commonly isolated fungi as degraders of both biodegradable and conventional polymers, it seemed that the results obtained during the study were in agreement with each other. The study of these fungi, their biodiversity and their capabilities will certainly be useful for application in other bio-based processes, but surely more information about these fungi and their enzymes is needed in order to achieve complete mineralization of bioplastics in different scenarios.