Biodegradação de poli(ácido lático) e polipropileno por Psilocybe castanella em processo de fermentação de resíduo de coco verde.

Abstract

The consumption of polymer products over the years has generated a large number of wastes, which accumulate in the oceans and landfills, resulting in serious environmental problems. Basidiomycetes are enzyme-producing fungi that hydrolyze polymers of lignocellulosic byproducts in fermentative processes and have aroused the academic and technological interest because they present desirable characteristics in the degradation of recalcitrant pollutants. In this context, this research evaluated the production of enzymes by Psilocybe castanella CCIBt 2781 in a semi-solid fermentation process (FSS) using agroindustrial residue, focusing on the biodegradation of poly(lactic acid) (PLA) and polypropylene (PP) from disposable cups. The fungus was cultivated in green coconut residue with the addition of soybean meal in order to maintain C/N of 32, with and without the addition of Synthetic Blue Dye of Remazol R (RBBR), used as an enzymatic mediator. Lactic activities were determined by the oxidation of ABTS and manganese peroxidase (MnP) by the oxidation of phenol red. The highest values of activity were obtained with 5 days of fermentation (272.13 UL-1 and 112.04 UL-1). The enzymes showed pH and T, of 4.8 and 60ºC. The degradation was evaluated by the properties and the morphology of the polymers by optical microscopy (MO) and scanning electron (SEM), by thermogravimetric (TG) and differential scanning calorimetry (DSC) and by spectroscopy in the infrared region with Fourier transform (FTIR) and X-ray diffraction (XRD). The morphology indicated that there was mycelial growth on the surfaces of the polymers, confirming the production of fungal biomass. After 60 days of incubation, the appearance of degradation byproducts was observed. The DSC and XRD analyzes indicated that the exposure time led to a decrease in the Tdc of the PLA and reduction of the amorphous phase and consequently the increase in crystallinity. The FTIR spectra indicated the occurrence of modifications that involve oxidation with the appearance of intense bands characteristic of degradation of these materials.