The Research Of Ethanol Production From Sargasso Fermentation

As one of biomass energy sources, ethanol has been considered to be an excellent alternative renewable fuel with characteristics in the safety, efficiency and non-pollution of combustion. Researches and developments of fuel ethanol has become a worldwide topical issue. However, along with the increase of population and the reduction of arable land, the supply of food and land become the bottleneck in the development of fuel ethanol. By comparison with terrestrial plants, algae grows faster, its yield is higher and it avoids the use of land. Algae such as brown seaweed contains rich carbohydrates which can be used to produce fuel alcohol directly or indirectly through bioconversion fermented with bacteria, yeast and other microorganisms.In this paper, Sargasso from the sea area of Weizhou Island, Beihai, Guangxi, is used as raw materials to analyze chemical composition, then mannitol which is considered to be the main component in Sargasso was used as research objects to investigate condition optimization of ethanol fermentation with Zymobacter palmae strain. Last, sulfuric acid was used to degrade the Sargasso into extract which used for ethanol fermentation by industrial yeast. The experimental results showed that the main compositions of Sargasso was combined with5.626%crude fat,11.585%crude protein,29.138%ash and53.606%carbohydrates with29.4%of reducing sugar in the carbohydrates. The part of carbohydrates was used to carry out ethanol fermentation; The optimal medium which mannitol was inverted to ethanol at high efficiency by Zymobacter palmae in250ml flask was mannitol20.Og/L, yeast extract0.5g/L, MgSO4·7H2O0.1g/L, KH2PO42.0g/L, K2HPO47.0g/L,(NH4)2SO41.0g/L, PH=6.0; And the best fermentation conditions to produce ethanol was the rotation speed of150rpm, temperature of28℃and fermentation liquor of150ml with a yield of0.429g ethanol/g mannitol. Ethanol conversion rate achieved the theoretical value of84%; Under conditions of fixed nitrogen and other nutrients, industrial yeast, R1-11, was use to produce ethanol in Sargasso extract, and the yield of ethanol was0.385%(V/V), but the ethanol yield of another industrial yeast, R1-12, was only0.275%(V/V).The ability of ethanol fermentation with Sargasso extract by R1-11was obviously higher than R1-12. The production of ethanol fermentation by R1-11was0.594%(V/V) in the medium with nitrogen addition, and the production of ethanol fermentation by R1-11was0.385%(V/V) in the medium without nitrogen addition. Therefore, the ratio of carbon and nitrogen has an important impaction on the Sargasso extract to improve the production of ethanol content.