Innovative method for improving fermentability of hemicellulosic hydrolysate by ozonation for sustainable xylitol production

Biomanufacturing xylitol, a sugar alcohol from surplus rice straw (RS) offers an opportunity for its green production alongside fostering a sustainable bioeconomy. However, RS pretreatment for hemicellulose extraction (majorly xylose), creates several toxic compounds as side products that impede microbial metabolism. So, the yeast mediated production of xylitol is a big challenge due to low fermentability of RS hydrolysate. The present work explored the efficacy of ozone and hydrogen peroxide, O 3 -H 2 O 2 (O-HP), in integration with activated charcoal (AC) for detoxifying and decolorizing RS hydrolysate. The effect on fermentability of RS hydrolysate was studied with the yeast, M. caribbica CP02 for xylitol production. O-HP/AC process was able to remove ∼88.86 % of the aromatics (furan and phenolic compounds) and color (ΔE = 46.2) without substantial xylose loss, which is a key drawback of conventional detoxification treatments. In 3 L batch bioreactor study, O-HP treated hydrolysate produced 43.14 ± 0.84 gL −1 xylitol titre and 0.74 gg −1 yield after 72 h of fermentation, comparable to semi-synthetic medium (44.6 ± 0.70 gL −1 , 0.77 gg −1 ). Simultaneously, a xylitol yield of 0.69 gg −1 and a productivity of 0.56 gL −1 h −1 at 72 h was observed in a 14 L bioreactor. Conclusively, the O-HP process is a promising intervention that can be used as a significant step during detoxification/decolorization for bioprocessing of xylitol. • Significant reduction in total phenols, furans, and color with O 3 -H 2 O 2 process. • No significant loss in xylose level in O-HP treated hydrolysate as compared to control. • Improved fermentability and xylitol yield of O 3 -H 2 O 2 treated hydrolysate. • CCD and ANN predicted responses for O 3 -H 2 O 2 process optimization. • Xylitol yield of 0.69 gg −1 and productivity of 0.56 gL −1 h −1 observed in 14 L bioreactor.