Xylitol production from non-detoxified and non-sterile lignocellulosic hydrolysate using low-cost industrial media components

Abstract

Immobilized Candida tropicalis cells in freeze dried calcium alginate beads were used for production of xylitol from lignocellulosic waste like corn cob hydrolysate without any detoxification and sterilization of media. Media components for xylitol fermentation were screened by statistical methods. Urea, KHPO and initial pH were identified as significant variables by Plackett-Burman (PB) design. Significant medium components were optimized by response surface methodology (RSM). Predicted xylitol yield by RSM model and experimental yield was 0.87 and 0.79 g/g, respectively. Optimized conditions (urea 1.5 g/L, KHPO 1.9 g/L, xylose 55 g/L, pH 6.7) enhanced xylitol yield by 32% and xylose consumption by twofold over those of basal media. In addition, the immobilized cells were reused five times at shake flask level with optimized medium without affecting the xylitol productivity and yield. Xylitol production was successfully scaled up to 7.5 L stirred tank reactor using optimized media. Thus, the optimized condition with non-detoxified pentose hydrolysate from corn cob lignocellulosic waste with minimal nutrients without any sterilization opens up the scope for commercialization of the process.

Enhanced xylitol production using non-detoxified xylose rich pre-hydrolysate from sugarcane bagasse by newly isolated Pichia fermentans

“…They found that medium components such as KH 2 PO 4 , yeast extract, (NH 4 ) 2 SO 4 and MgSO 4 ·7H 2 O had a significant effect on xylitol production. Likewise, Yewale et al performed Plackett–Burman (PB) design followed by CCD and reported components such as KH 2 PO 4 , yeast extract and xylose are the critical factors for xylitol production [ 36 ]. These studies indicate the importance of statistical method to identify the vital components affecting growth and product formation.…”

Enhanced xylitol production using non-detoxified xylose rich pre-hydrolysate from sugarcane bagasse by newly isolated Pichia fermentans

“…The yeast accumulated 3 2.0 g/L with conversion yield of 0.71 g/g from SCB while xylitol titer and yield achieved with rice straw were 12.5 g/L and 0.51 g/g, respectively. Similarly, de Freitas Branco et al [36]…”

“…3A & 3B). The xylose consumption was smooth as with pure xylose and a large fraction of initial xylose concentration of 20.0 g/L was consumed within 48 h. Both the strains exhibited high cell growth (OD 600 :[35][36][37][38] concomitant with xylose assimilation. The xylitol titer and yield obtained with mutant strain were 11.8 g/L and 0.59 g/g while wild type strain was able to accumulate 9.3 g/L xylitol with conversion yield of 0.46 g/g.…”

Assessing the Potential of Newly Isolated Pichia Fermentans for Xylitol Production Using Non-Detoxified Xylose Rich Pre-Hydrolysate Derived from Sugarcane Bagasse

“…5 A, D & E) and KH 2 PO 4 ( Fig. 5 B, [27] performed Plackett-Burman (PB) design followed by CCD and reported components such as KH 2 PO 4 , yeast extract and xylose are the key factors for xylitol production. These studies indicate the importance of statistical method to identify the important components affecting growth and product formation.…”