Bioethanol Potential of Brown Macroalgae (Sargassum spp.)

Macroalgae has a number of potential advantages as a source of bioethanol principally due to its fermentable carbohydrates, such as laminarin, mannitol and cellulose. However, limited studies have been published detailing algae-derived bioethanol. This study aimed to maximize the use of macroalgae as a substrate by providing summarized ideal results starting from algal feedstock selection, feedstock pre-treatment, saccharification up to fermentation. Tested parameters for these actual production processes which include reaction temperature, medium pH and concentration have shown that Sargassum is the best brown seaweed genus to be utilized for ethanol synthesis. Ethanol was produced from various carbohydrates extracted from Sargassum using sole substrate and mixed substrate fermentations. For sole substrate fermentation, best alcohol concentration obtained was 0.37% (v/v) using 10 g L-1 crude extracted Sargassum mannitol solution, incubated for about 48 h. For mixed substrate conversion, best ethanol concentration was 0.017% (v/v), achieved by fermenting a solution with a composition ratio of 2:1 mg mL(-1) glucose from cellulose to mannitol, under reaction temperature of 30 degrees C and medium pH 4.5. By ensuring the availability of alternative and renewable energy from indigenous feedstocks such as macroalgae, the country would not only become less dependent on imported fuels but also become more sustainable without causing any danger to the environment or threat to food security.