Process strategies for enhanced sugar recovery from de-oiled rice bran for xylitol production using Pichia fermentans NCIM 3638

Amidst advancements underway in exploiting lignocellulosic biomass efficiently, there is a noticeable dearth of scientific data concerning the utilization of de-oiled rice bran (DRB), an agro-industrial residue of the rice bran oil processing industry for the production of commercially valuable chemicals. The biochemical analysis of DRB biomass revealed that its holocellulosic content was 39.09 % w/w. A combined pretreatment and saccharification strategy was employed with mono and co-culture of two fungal species namely white rot fungi and Aspergillus niger sequentially followed by mild acid treatment (1 % (v/v) H₂SO₄) to extract maximum sugar from DRB biomass. This comprehensive treatment resulted in a total sugar yield of 518.3 mg/g of DRB and the maximum delignification and saccharification achieved were 75.4 % (w/w) and 78.5 % (w/w) respectively. At 96 h of batch fermentation, Pichia fermentans NCIM 3638 with detoxified DRB hydrolysate achieved a maximum xylitol yield and concentration of 0.48 g/g of xylose and 23.56 g/L and was confirmed through HPLC analysis. The produced xylitol was crystallized with maximum yield of 73.22 %. Further, an unstructured kinetic model was employed to study the feasibility of xylitol production. This work validates that DRB biomass possesses significant promise as a highly efficient feedstock for the bioproduction of xylitol.