Valorisation of sawdust-based spent mushroom substrate for sustainable xylooligosaccharides production using low-cost crude xylanases from Aspergillus flavus KUB2

Abstract

Spent mushroom substrate (SMS), a lignocellulosic waste after mushroom production is generally discarded without proper management. There is increasing interest in the sustainable transformation of lignocellulosic waste into high-value products. Within this context, the present study investigated the potential of the SMS from the cultivation of Pleurotus pulmonarius and Auricularia auricula on rubber tree wood sawdust as substrates for xylooligosaccharides (XOS) production. SMS samples from these two edible mushrooms were extracted using alkaline xylan extraction, producing maximum true recovery amounts of xylan in the range 34.61%–37.49% using 18% NaOH at 70 °C for 3 h. Production of XOS from alkaline-extracted xylan from the SMS samples of both mushroom species using economically crude xylanases from Aspergillus flavus KUB2 resulted in XOS (X2–X5) production of 241.47–249.04 mg/g, with X3 as the predominant XOS product. The produced XOS had excellent prebiotic activity and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and contained high total phenolic contents. The combined beneficial bioactivities in terms of prebiotic and antioxidant properties suggested that the XOS produced from sawdust-based SMS samples of P. pulmonarius and A. auricula could be promising ingredients for both food and pharmaceutical applications.