Bioethanol production from sugarcane molasses by co-fermentation of Saccharomyces cerevisiae isolate TA2 and Wickerhamomyces anomalus isolate HCJ2F-19

Purpose Co-culturing is a widely used method to improve bioethanol production from biomass enriched in fermentable sugars.

This study aims to produce bioethanol from sugarcane molasses by simultaneous co-fermentation of S. cerevisiae isolate TA2 and W. anomalus isolate HCJ2F-19.

Methods Response surface methodology (RSM) based on the central composite design (CCD) was employed to optimize fermentation conditions, including mixing rate (110–150 rpm), temperature (25–35 °C), molasses concentration (25–35 ^obrix), and incubation time (36–72 h).

The ethanol concentration was analyzed using HPLC equipped with a UV detector.

Results The monoculture S. cerevisiae isolate TA2 produced 17.2 g.L^−1 of ethanol, 0.33 g.g^−1 of ethanol yield, and 0.36 g.L^−1.

h^−1 of productivity compared to W. anomalus isolate HCJ2F that produced 14.5 g.L^−1, 0.30 g.g^−1 and 0.28 g.L^−1.

h^−1 ethanol, ethanol yield, and productivity under laboratory conditions, respectively.

In comparison to single cultures of S. cerevisiae TA2 and W. anomalus HCJ2F, the co-fermentation using both isolates showed an increased ethanol yield of 29% and 53% compared to the single species fermentations, respectively.

The results showed that the growth of W. anomalus HCJ2F-19 and S. cerevisiae TA2 was not influenced by each other during the co-fermentation process.

The one variable at a time optimization (OVAT) analysis resulted in an ethanol concentration of 26.5 g.L^−1 with a specific yield and productivity of 0.46 g.g^−1, 0.55 g.L^−1.

h^−1, respectively, at pH 5.5, 25 ^obrix, 48 h, 150 rpm, 30 °C, 60:40 inoculum ratio, and 10% overall inoculum size.

The maximum ethanol concentration of 35.5 g.L^−1 was obtained by co-fermentation using the RSM-CCD tool at 30 ^obrix, 30 °C, 54 h, and 130 rpm.

Conclusion The results suggested that the co-fermentation of S. cerevisiae isolate TA2 and W. anomalus isolate HCJ2F improves bioethanol production from sugar cane molasses under optimum fermentation conditions.