Fermentative production of xylitol from agro-industrial biomass using novel indigenous bacterial isolates

Abstract

This study focuses on the microbial production of xylitol, a low-calorie sugar alcohol widely used in food and pharmaceutical applications, using bacterial strains isolated from agricultural soils. Unlike conventional chemical methods that rely on high temperature, pressure, and costly catalysts, this work explores a more sustainable and economical alternative based on microbial fermentation of agricultural waste substrates. A total of twenty microbial isolates were obtained and screened for their ability to utilize xylose and produce xylitol, out of which four bacterial strains—Escherichia coli, Pseudomonas sp., Citrobacter sp., and Enterobacter sp.—were selected for further evaluation. Process optimization was carried out using Response surface methodology (RSM) with a central composite design to study the combined effects of pH, inoculum concentration, incubation time, D-xylose, and yeast extract. Among the tested strains, Citrobacter sp. showed the best performance, with a maximum xylitol concentration of 124.2 g/L observed at 102 hours. The model predicted optimal conditions at pH 7, 3% inoculum, and 120 hours of incubation. Overall, the findings suggest that Citrobacter sp. has good potential for converting low-cost agricultural residues into xylitol, supporting the development of more sustainable and economically viable bioprocesses.