Bioethanol production using carbohydrate-rich microalgae biomass as feedstock

• Published in: Bioresource technology 2013-05, Vol.135, p.191-198
• Main Authors: Ho, Shih-Hsin, Huang, Shu-Wen, Chen, Chun-Yen, Hasunuma, Tomohisa, Kondo, Akihiko, Chang, Jo-Shu
• Format: Article
• Language: English
• Subjects: Acid hydrolysis; Biofuels - microbiology; Biomass; Biotechnology - methods; Carbohydrate; Carbohydrate Metabolism - drug effects; Carbohydrates; Carbohydrates - biosynthesis; Chlorella vulgaris; Chlorella vulgaris - drug effects; Chlorella vulgaris - growth & development; Chlorella vulgaris - metabolism; Enzymatic hydrolysis; Ethanol; Ethanol - metabolism; Ethyl alcohol; Feedstock; Fermentation - drug effects; Glucose; Glucose - biosynthesis; Glucosidases - metabolism; Hydrolysates; Hydrolysis; Hydrolysis - drug effects; Lipids - analysis; Microalgae; Microalgae - drug effects; Microalgae - growth & development; Microalgae - metabolism; Nitrates - analysis; Nitrogen - pharmacology; Proteins - analysis; Sulfuric Acids - pharmacology; Time Factors; Zymomonas - drug effects; Zymomonas - metabolism
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2012.10.015

► A sugar-rich Chlorella vulgaris FSP-E strain was used as feedstock for ethanol production. ► Enzymatic and acidic hydrolyses can efficiently saccharify the microalgae biomass. ► SHF & SSF processes produced ethanol from the microalgae biomass with high yield. ► SSF process gave better ethanol production performance with a 92% theoretical yield. This study aimed to evaluate the potential of using a carbohydrate-rich microalga Chlorella vulgaris FSP-E as feedstock for bioethanol production via various hydrolysis strategies and fermentation processes. Enzymatic hydrolysis of C. vulgaris FSP-E biomass (containing 51% carbohydrate per dry weight) gave a glucose yield of 90.4% (or 0.461g (gbiomass)−1). The SHF and SSF processes converted the enzymatic microalgae hydrolysate into ethanol with a 79.9% and 92.3% theoretical yield, respectively. Dilute acidic hydrolysis with 1% sulfuric acid was also very effective in saccharifying C. vulgaris FSP-E biomass, achieving a glucose yield of nearly 93.6% from the microalgal carbohydrates at a starting biomass concentration of 50gL−1. Using the acidic hydrolysate of C. vulgaris FSP-E biomass as feedstock, the SHF process produced ethanol at a concentration of 11.7gL−1 and an 87.6% theoretical yield. These findings indicate the feasibility of using carbohydrate-producing microalgae as feedstock for fermentative bioethanol production.