Effects of nutrients and process variables on xylitol production by Debaryomyces hansenii var hansenii using wheat straw

摘要

The effects of nutrients and process variables on xylitol production by Debaryomyces hansenii var hansenii in wheat straw hemicellulose hydrolysate was studied. Screening and optimization were done using statistical methodology based on experimental designs. Various nutrients were designated and screened by Plackett-Burman design. Selected nutrients are optimized to maximise the xylitol production by Box-Behnken design of Response surface methodology (RSM). The optimum level (g/L): (NH4)jS04-4.34, MgS04.7H20-1.3,peptone- 5.1 and KHjPCy 3.63 and influence of various process variables on the xylitol production was evaluated. The optimum levels were quantified by central composite design using RSM. The optimal process variables levels were temperature(31.3° C), substrate concentration (3.5 g/L), pH (7.35), agitation speed (194.4 rpm) and inoculum size (3.5 mL). Underthe conditions the xylitol production attained the maximum yield of (0.75 g g~(-1)). Under appropriate level of nutrients and process variables, the experimental analysis reveals the maximum yield of xylitol for wheat straw using Debaryomyces hanseniivar hansenii.