Solid-state bioprocessing of sugarcane bagasse with Auricularia fuscosuccinea for phenolic compounds extraction

Abstract

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 b-glucosidases, increasing free phenolics. Auricularia is a food-grade genus capable of producing b-glucosidases. The aim of this work was (I) to determine naturally occurring species of Auricularia 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 A. fuscosuccinea. We determined b-glucosidase activity by fluorescence plate assay of the five isolated strains and adjusted an optimal temperature for mycelial growth at 30 C. A. fuscosuccinea LBM 243 was chosen for solid-state bioprocessing of sugarcane bagasse. b-glucosidase activity (12.2 ± 0.62 U l1 ) and protein content (51.58 ± 6.26 mg l1 ) 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.