Enhanced ethanol production from sugarcane juice by galactose adaptation of a newly isolated thermotolerant strain of Pichiakudriavzevii

The thermotolerant yeast strain isolated from sugarcane juice through enrichment technique was identified as a strain of Pichiakudriavzevii (Issatchenkiaorientalis) through molecular characterization. The P. kudriavzevii cells adapted to galactose medium produced about 30% more ethanol from sugarcane juice than the non-adapted cells. The recycled cells could be used for four successive cycles without a significant drop in ethanol production. Fermentation in a laboratory fermenter with galactose adapted P. kudriavzevii cells at 40 °C resulted in an ethanol concentration and productivity of 71.9 g L−1 and 4.0 g L−1 h−1, respectively from sugarcane juice composed of about 14% (w/v) sucrose, 2% (w/v) glucose and 1% (w/v) fructose. In addition to ethanol, 3.30 g L−1 arabitol and 4.19 g L−1 glycerol were also produced, whereas sorbitol and xylitol were not formed during fermentation. Use of galactose adapted P. kudriavzevii cells for ethanol production from sugarcane juice holds potential for scale-up studies.

Research highlights
► Adaptation of Pichia kudriavzevii to galactose improves ethanol production from sugarcane juice.
► Galactose adapted Pichia kudriavzevii efficiently fermented sugarcane juice to ethanol at 40 °C.
► Ethanol productivity of 4g/l/h from sugarcane juice could be achieved.
► Yeast cells could be efficiently recycled for four successive cycles.