Solid-state bioprocessing of sugarcane bagasse with <i>Auricularia fuscosuccinea</i> for phenolic compounds extraction

Sugarcane bagasse is a natural source of phenolic compounds. However, these compounds are bound to lignocellulose components, reducing their ability to function as good antioxidants. These linkages are hydrolyzed by enzymes like <i>β</i>-glucosidases, increasing free phenolics. <i>Auricularia</i> is a food-grade genus capable of producing <i>β</i>-glucosidases. The aim of this work was (I) to determine naturally occurring species of <i>Auricularia</i> and (II) to obtain phenolic compounds through the solid-state bioprocessing of sugarcane bagasse. We have successfully isolated five strains that were assigned to the taxon <i>A. fuscosuccinea</i>. We determined <i>β</i>-glucosidase activity by fluorescence plate assay of the five isolated strains and adjusted an optimal temperature for mycelial growth at 30 °C. <i>A. fuscosuccinea</i> LBM 243 was chosen for solid-state bioprocessing of sugarcane bagasse. <i>β</i>-glucosidase activity (12.2 ± 0.62 U l⁻¹) and protein content (51.58 ± 6.26 mg l⁻¹) were highest on day 20 of culture. The maximum value of total phenolic content (507.5 ± 9.05 mg l⁻¹) was obtained at day 20 and antioxidant capacity (34.44% ± 11.20) was highest at day 10, both in ethanolic extracts. The best performance of ethanol against methanol extraction in this work is highlighted considering ethanol to be a safe, efficient, and low-cost solvent.