José Rodrigo Ferreira Maciel¹, Jonatas V. de Souza ¹, Rodolfo Dantas Lima Junior¹, Taicia Pacheco Fill¹

Polymers are essential materials in contemporary society due to their versatility, broad range of applications, and functional utility, being extensively incorporated into everyday items. Since their emergence in the early 20th century, plastics have become integral to various domains, including packaging, industrial manufacturing, and technology. However, the increase in plastic consumption has brought significant environmental concerns, mainly because a substantial amount of improperly discarded plastic persists in the environment due to its resistance to degradation. To mitigate the environmental burden caused by plastic pollution, several strategies have been pursued, among which the creation of biodegradable polymers and the use of microorganisms to enhance degradation are particularly promising. This research investigated the biodegradation capability of a polymeric composite composed of recycled polyethylene and a plant-based matrix derived from cocoa shell waste by the filamentous fungus Trichoderma sp.

Additionally, an untargeted metabolomics approach using LC-MS/MS was employed to evaluate the biodegradation products and to identify metabolites produced by the fungus arising from the degradation process. Molecular networking tools from the GNPS platform were applied to support metabolite dereplication. The use of online databases like GNPS and in silico software such as Sirius, allowed to annotate two diketopiperazines, two organic acids, as well as terpenoids and isocoumarins, compounds known for their potential industrial applications due to their various biological activities. Statistical analyses revealed that these ions significantly increased during the biodegradation process. PCA (Principal Component Analysis) showed clear metabolic changes in the fungal treatment compared to polymer and fungal controls, indicating distinct group separation. Scanning electron microscopy (SEM) further confirmed the interaction between the fungus and the polymer, with visible signs of material degradation. Mechanical testing through tensile strength (TS) measurements demonstrated the impact of fungal activity on the polymer’s physical properties. The fungus exhibited strong adhesion to the polymer surface and was capable of penetrating its structure.

Overall, the study highlights the potential of incorporating cocoa shell residues into polymer matrices as a sustainable alternative to conventional plastics. Beyond improving mechanical strength, this approach facilitates fungal colonization and biodegradation, enabling the formation of valuable secondary metabolites. Investigating the degradation of such cocoa-based polymer composites with Trichoderma sp. offers valuable insights into the biological mechanisms underlying fungal biodegradation of synthetic materials.

Agradecimentos: Acknowledgments to the funding agencies CNPq, CAPES, and FAPESP. I also thank the Institute of Chemistry at UNICAMP for providing the space and resources necessary for the development of my research.