Abstract

Microalgal carbohydrates can serve as feedstock for bioethanol production. Environmental and/or nutritional factors influence the carbohydrate content of microalgae and optimization of culture condition has a key role in the economic production of bioethanol. This research has evaluated the optimization of the carbohydrate content of a marine microalga isolate from the Persian Gulf. The Plackett-Burman design was used to screen the most effective parameters responsible for carbohydrate production. Then, the levels of two effective factors, total phosphate (KH₂PO₄+K₂HPO₄) and initial pH, were optimized by two types of Response Surface Method designs (Central Composite and historical data designs). Maximum carbohydrate production was obtained at a low concentration of phosphate (0.031 g/L) and initial pH of 5.95. Under optimal condition, the concentration of carbohydrate was increased by 1.9 folds, from 0.12 g/L (0.2 g/g of dry biomass) to 0.230 g/L (0.365 g/g of dry biomass). The carbohydrate content of microalga hydrolysate was also evaluated by the HPLC method, and the results showed that glucose made about 3.19% (w/w) of total carbohydrates. This study represents the isolation and determination of a promising native and non-invasive microalga for bioethanol production, and subsequently enhancement of its carbohydrate content for the same goal.

摘要

微藻碳水化合物可以作为生物乙醇生产的原料。环境和/或营养因素影响微藻的碳水化合物含量，培养条件的优化在生物乙醇的经济生产中具有关键作用。这项研究评估了波斯湾海洋微藻分离物碳水化合物含量的优化。Plackett-Burman 设计用于筛选负责碳水化合物生产的最有效参数。然后，两个有效因素的水平，总磷酸盐（KH ₂ PO ₄ +K ₂ HPO ₄) 和初始 pH 值，通过两种类型的响应面方法设计（中心复合设计和历史数据设计）进行了优化。在低浓度的磷酸盐 (0.031 g/L) 和 5.95 的初始 pH 值下获得了最大的碳水化合物产量。在最佳条件下，碳水化合物的浓度增加了 1.9 倍，从 0.12 g/L（0.2 g/g 干生物质）增加到 0.230 g/L（0.365 g/g 干生物质）。微藻水解物的碳水化合物含量也通过高效液相色谱法进行了评估，结果表明葡萄糖约占总碳水化合物的 3.19% (w/w)。这项研究代表了一种用于生物乙醇生产的有前途的天然和非侵入性微藻的分离和测定，并随后为同一目标提高了其碳水化合物含量。