Use of Trichoderma, Aspergillus, and Rhizopus Fungi for the Biological Production of Hydrolytic Enzymes and Uronic Acids from Sargassum Biomass

Abstract

The objective of this study was the evaluation of fungal solid-state fermentation (SSF) for the production of alginate lyase and extraction of uronic acids from Sargassum sp. For this purpose, the fungi Trichoderma asperellum, Aspergillus oryzae, and Rhizopus oryzae were applied (alone or combined) to Sargassum sp. biomass through SSF (10E+7 spores gbiomass−1, 30 °C, and 7 days of treatment). In general, individual SSF with all three fungi degraded the biomass, achieving a marked synergy in the production of cellulase, laminarinase, and alginate lyase activities (especially for the last one). Trichodermawas themost efficient species in producing laminarinase, whereas Rhizophus was the best option for producing alginate lyase. However, when dual combinations were tested, the maximal values of alginate lyase activities were reached (13.4 ± 0.2 IU gbiomass−1 for Aspergillus oryzae and Rhizopus oryzae). Remarkably, uronic acids were the mainmonomeric units from algal biomass solubilization, achieving a maximum yield of 14.4 mguronic gbiomass−1, with the A + R condition being a feasible, eco-friendly alternative to chemical extraction of this monomer. Additionally, the application of all the fungal pretreatments drastically decreased the total phenolic content (TPC) in the biomass from 369 mg L−1 to values around 44–84 mg L−1, minimizing the inhibition for possible subsequent biological processes in which the residual solid can be used.