Journal of Photochemistry and Photobiology (Dec 2022)
Photodynamic treatment affects the secreted antioxidant and glycoside hydrolases activities produced by Humicola grisea var. thermoidea and Penicillium echinulatum in agro-industrial substrates
Abstract
The exposure of fungi to photoactivatable dyes can modify the expression of enzymes of interest in several areas such as industrial enzyme production, bioremediation of urban residues and nanocomposites stabilization. Alternatives that favor the use of plant biomass, or improve its exploitation should be prioritized, considering the scarcity of fossil resources and their polluting nature. Here, we investigated the effect of photodynamic treatment (PDT) mediated by an aluminum-phthalocyanine chloride nanoemulsion (AlPc-NE) in two hydrolases-producing filamentous fungi, Humicola grisea and Penicillium echinulatum, and its implication in the hydrolysis of agro-industrial substrates as steam exploded sugarcane-bagasse (SCB) and wheat bran (WB). The fungi hyphae were exposed to different concentrations of AlPc-NE and photosensitizer internalization was measured by spectrophotometry and fluorescence microscopy. Once the photosensitizer retention patterns were established, PDT mediated by 300 and 600 nM AlPc-NE was performed and the cultures viability was analyzed. After PDT, H. grisea and P. echinulatum were grown in SCB, WB or glucose and subsequently analyzed after 96 h. The amount of soluble secreted proteins, total antioxidant activity in the supernatant, CMCase, xylanase and FPase enzymes activity were evaluated. After irradiation, there was no change in the cultures growth or viability. Changes in the total amount of secreted protein, total antioxidant activity, CMCase and xylanase activities were observed after PDT in a photosensitizer concentration-dependent manner, and accordingly to the evaluated substrate and fungus species. Xylanase activity was the most impacted while FPase remained virtually unchanged in both fungi species. We concluded that PDT can be employed to modulate the production of certain fungal hydrolases of industrial interest.
