Utilization of Pachysolen tannophilus and Pichia kudriavzevii for the production of xylitol on undetoxified corn cob hydrolysates
¹University of Ilorin, Faculty of Life Sciences, Department of Microbiology, Nigeria
²Smallfood Inc., Dartmouth, Nova Scotia, Canada
³University of Sharjah, Research Institute of Sciences and Engineering, 27272 Sharjah, Biomass & Bioenergy Research Group, Center for Sustainable Energy and Power Systems Research, United Arab Emirates
⁴Estonian University of Life Sciences, Institute of Forestry and Engineering, Chair of Biosystems Engineering, Kreutzwaldi 56, EE51006 Tartu, Estonia
Xylitol is a natural polyol with broad applications in the food and pharmaceutical industries. However, its large-scale production through chemical means is still an expensive and not environmentally friendly process. Therefore, great attention has been paid to low-cost and renewable substrates like corn cobs (CC), which can be utilized to improve the economic outlook of xylitol production. In this study, CC were used as a feedstock for xylitol production, with the help of yeasts and filamentous fungi. The results obtained in this study showed that the amount of xylitol produced from CC hydrolysate was similar to the amount of xylitol obtained on xylose substrate. Overall, yeastproduced higher amounts of xylitol than filamentous fungi. Pachysolen tannophilus had the highest xylitol production at pH 5.0, 72 h fermentation time, substrate concentration 15%, and inoculum size 1.5×108 cfu mL-1, while Pichia kudriavzevii performed better at pH 5.0, with a 72 h fermentation time, substrate concentration of 20%, and inoculum size of 2.5×108 cfu mL-1. When comparing the combined optimal parameters with and without supplementation, supplementation with 1.5% methanol, has increased the xylitol production of P. tannophilus and P. kudriavzevii by 31% and 18.6%, respectively. These findings demonstrate the robustness of these yeast strains for sustainable and cost-effective xylitol production from CC waste.