Abstract

Microalgae are promising raw materials for biorefinery systems as they are rich in nutrients (proteins, carbohydrates, lipids, vitamins, pigments). Although there are different studies on the production of ethanol from microalgae with different types of pre-treatments for the utilisation of whole biomass, researches of ethanol production from residues of protein extraction from defatted biomass of Arthrospira platensis biomass has not been found in the literature. In this context, the objective of this study was to use the residues of the protein extraction process to produce ethanol (byproduct) in a biorefinery concept. Enzymatic hydrolysis (pH 5.5; 50 °C) were carried out with different concentrations (0.5, 1.0, 1.5% (v/v)) of the enzymes α-amylase and amyloglucosidase (AMG), added simultaneously. For the fermentation stage conducted with Saccharomyces cerevisiae, four different media were tested (H – pure hydrolysate; C1 – control 1, reduced sugars in the same proportion of medium H; C2 – control 2, simulating the production of sugarcane ethanol; HS – hydrolysate supplemented with nutrients in order to obtain the same composition as C2). The medium H presented better results than the others, it produced 8.06 g/L of ethanol over 12 h, with a 100% theoretical yield of ethanol. These results indicate that the nutrients present in the hydrolysate of the residual fractions were sufficient to promote yeast growth and ethanol production. Moreover, the results from this work show the feasibility to obtain protein concentrate and ethanol from Arthrospira platensis, in an integrated process.

• HIGHTLIGHTS

• It was possible to perform an integrated process to extract proteins and produce bioethanol from S. platensis.

• Nutrients on hydrolysate from residual fractions was sufficient to promote yeast growth and bioethanol production.

• Bioethanol production from hydrolysed residual fractions was 100% efficient.

摘要

微藻富含营养（蛋白质、碳水化合物、脂类、维生素、色素），是生物精炼系统的有前途的原材料。尽管对利用不同类型的预处理以利用整个生物质的微藻生产乙醇的研究存在不同的研究，但从钝顶节旋藻脱脂生物质的蛋白质提取残留物生产乙醇的研究生物量尚未在文献中发现。在这种情况下，本研究的目的是利用蛋白质提取过程的残留物在生物精炼概念中生产乙醇（副产品）。使用不同浓度（0.5、1.0、1.5% (v/v)）的酶α-淀粉酶和淀粉葡萄糖苷酶（AMG）进行酶水解（pH 5.5；50°C），同时加入。对于用酿酒酵母进行的发酵阶段, 测试了四种不同的培养基（H——纯水解物；C1——对照 1，与培养基 H 相同比例的还原糖；C2——对照 2，模拟甘蔗乙醇的生产；HS——水解物补充营养以获得与 C2 的成分相同）。培养基 H 表现出比其他培养基更好的结果，它在 12 小时内产生 8.06 g/L 的乙醇，乙醇的理论产率为 100%。这些结果表明残留部分的水解产物中存在的营养物质足以促进酵母生长和乙醇生产。此外，这项工作的结果表明，在集成过程中从钝顶节螺旋体中获得蛋白质浓缩物和乙醇的可行性。

• 亮点

• 有可能执行一个集成过程来从S. platensis 中提取蛋白质和生产生物乙醇。

• 残留馏分水解产物中的营养物质足以促进酵母生长和生物乙醇生产。

• 从水解残余馏分生产生物乙醇的效率为 100%。