A Statistical Approach to Optimize Xylitol Production by <i>Debaryomyces nepalensis</i> NCYC 3413 <i>in Vitro</i>

Abstract

Debaryomyces nepalensis NCYC 3413, halotolerant yeast isolated from rotten apple, was capable of utilizing components of hemicellulose hydrolysate such as glucose, galactose, mannose, xylose and arabinose. The organism utilizes xylose as a sole carbon source and produces xylitol. The Plackett-Burman design was applied to determine the specific medium components affecting xylitol production and found that xylose, K 2 HPO 4 , and ZnSO 4 were critical in augmenting xylitol production. These significant parameters were further optimized using response surface methodology. The optimum concentrations of xylose, K 2 HPO 4 , and ZnSO 4 were found to be 100 g/l, 10.6 g/l and 8.9 mg/l respectively. Under these optimal conditions the xylitol production increased from 27 g/l to 36 g/l with a yield of 0.44 g/g (57% increase in total yield). In addition, formation of the by product (glycerol) was decreased under optimal conditions.

Production of ethanol and arabitol by Debaryomyces nepalensis: influence of process parameters

“…Debaryomyces nepalensis NCYC 3413 , a halotolerant strain that has been previously isolated from rotten apple, is capable of utilizing both hexoses and pentoses; and is also important in production of commercially valuable products such as arabitol, xylitol and ethanol (Gummadi and Kumar 2006a; Kumar and Gummadi 2011; Kumdam et al 2012). In this study, the metabolism of D. nepalensis using glucose as the carbon source has been studied under different physiological conditions in both shake flask and bioreactor.…”

Multi response optimization for enhanced xylitol production by Debaryomyces nepalensis in bioreactor

“…During the initial four experiments, the levels of the variables were pH: 4–6; agitation rate: 300–500 rpm; aeration rate: 0.5–1.5 vvm. The above levels were set up based on the previous shake flask experiments (Kumdam et al 2012 ). Initially, the four experiments have been conducted as shown in Table 1 .…”

“…Semi-synthetic medium containing xylose—100 g L −1 ; (NH 4 ) 2 SO 4 —3 g L −1 ; MgSO 4 —0.1 g L −1 ; K 2 HPO 4 —6 g L −1 ; Na 2 HPO 4 —3 g L −1 ; yeast extract—1 g L −1 ; CaCl 2 ·2H 2 O—147 mg L −1 ; citric acid—6.9 mg L −1 ; FeCl 3 —10 mg L −1 ; MnSO 4 ·H 2 O—3.4 mg L −1 ; ZnSO 4 ·7H 2 O—4.3 mg L −1 ; CuSO 4 ·5H 2 O—0.25 mg L −1 ; 3 N H 3 PO 4 and 3N NaOH were used to adjust pH. All the components were autoclaved separately and mixed subsequently as described earlier (Kumdam et al 2012 ).…”