The Isolation and Performance Studies of an Alginate Degrading and Ethanol Producing Strain

W. Zhang, J. Zhang and H. Cui

Abstract
Bioethanol production from brown algae is a promising way to help solve the energy problem. Alginate is a major component of brown algae, but it cannot be utilized for ethanol fermentation. In order to improve the utilization rate of algae, high alginate fermentation strains should be obtained. In this research, alginate fermentations were carried out and 6 alginate degrading strains were obtained from different samples. The ethanol yield of strain 5 was the highest, which was 0.154 g g–1 (ethanol to alginate). Identification of strain 5 revealed that it was 99 % identical to Meyerozyma guilliermondii. The transform procedure from alginate to ethanol by M. guilliermondii was studied. The crude enzymes of alginate lyase and ethanol dehydrogenase were extracted, and the enzyme activity was measured. The main polysaccharides of brown algae are alginate, laminaran and mannitol. So the fermentation experiments were carried out with different substrates, such as laminaran, mannitol, Laminaria japonica and acid hydrolysate of L. japonica. The ethanol yield rate of L. japonica was the highest, reaching 0.237 g g–1 ethanol to L. japonica. This showed that strain 5 might be a promising strain for ethanol production from algae.

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Keywords
alginate fermentation strains, ethanol production, ethanol dehydrogenase, alginate lyase