Potential of bioethanol production from Nypa fruticans sap by a newly isolated yeast Lachancea fermentati

Abstract

Four isolated yeast strains from nypa sap: Saccharomyces cerevisiae, Candida tropicalis, Candida parapsilosis, and Lachancea fermentati were screened for their abilities to produce ethanol from Nypa fruticans sap. Fermentation was carried out in shake flasks at 30 °C, 200 rpm utilizing 50 g/l sugar of nypa sap. L. fermentati produced the highest ethanol level (18.7 g/l) with 75% efficiency, thus it was selected for further process optimization. Aiming to obtain high yields of ethanol, orthogonal experiments of ethanol fermentation from nypa sap using L. fermentati were carried out in 250 ml shake flasks to investigate the effects of the main parameters: temperature, pH, substrate concentration, and fermentation time. The results showed that the optimum conditions for bioethanol production were temperature of 30 °C, pH 5.4, substrate concentration of 110 g/l, and fermentation time of 20 h. The model predicted that the maximum concentration of ethanol produced under the above optimum conditions was 46.83 g/l. Verification experiments were carried out at the corresponding parameters, and the results were in close agreement with the model prediction giving 46.4 g/l ethanol production and 82% efficiency close to the theoretical yield. Nypa sap is a good potential substrate as well as a new resource for ethanol production by a local yeast isolate.