Evaluation of Rice Bran as a Supplement for Production of Bioethanol by Saccharomyces cerevisiae

ABSTRACT There is an increase in researches to create alternative fuels through the use of biomass and agroindustrial lignocellulosic residues. The present study proposes the use of rice bran as source of energy with the potential to enhance bioethanol production. Using different concentrations of cells (1-5 g.L–1) and rice bran (2.5-7.5 g.L –1) with Saccharomyces cerevisiae, a factorial design 22 was carried out. The nutrient source provided by rice bran affects the substrate conversion in product (Yp/s) response in a quadratic form, but its linear form showed no significant effect (α = 0.05). When it comes to means, the best results were obtained for 12 h and for fermentation medium 2 (23.320 g.L–1 of ethanol), which contained the highest rice bran concentration and the lowest initial cell concentration. Medium 3, consisting of 2.5 g.L–1 and 5 g.L –1 of rice bran and cells, respectively, showed the lowest K s (4.434 g.L–1).

摘要：当前利用生物质及农业工业木质纤维素残渣制备替代燃料的研究呈增长趋势。本研究提出以米糠作为能源原料，具备提升生物乙醇生产潜力的应用路径。本研究以酿酒酵母（Saccharomyces cerevisiae）为实验菌株，设置菌体浓度范围1~5 g·L⁻¹、米糠浓度范围2.5~7.5 g·L⁻¹，开展了2²析因实验设计。米糠提供的营养源对产物对底物得率（Yp/s）的响应呈二次函数关系，但其线性效应未达到显著水平（α=0.05）。就均值结果而言，发酵时长12小时且采用发酵培养基2（乙醇浓度达23.320 g·L⁻¹）的实验组获得最优结果，该培养基含有最高浓度的米糠与最低的初始菌体浓度。培养基3的组成为米糠与菌体浓度分别为2.5 g·L⁻¹与5 g·L⁻¹，其饱和常数（Ks）最低，为4.434 g·L⁻¹。