Bioethanol from hydrolyzed Spirulina (Arthrospira platensis) biomass using ethanologenic bacteria

Photosynthetic microorganisms are considered excellent feedstock for biofuel production in developing biomass production technologies. A study was conducted to evaluate ethanol production with the sequential enzymatic saccharification and fermentation of Arthrospira platensis (Spirulina) biomass with the metabolically engineered Escherichia coli strain MS04. A. platensis was cultivated semicontinuously in an open raceway pond, and the carbohydrate content was determined to be as high as 40%. The enzymatic saccharification was designed to release the maximum amount of glucose. After 40 h of enzymatic saccharification, 27 g L-1 of monosaccharides was obtained. These slurries were fermented with ethanologenic bacteria, achieving 12.7 g L-1 ethanol after 9 h of fermentation, which corresponds to 92% conversion yield of the glucose content in the hydrolysate, 0.13 g of ethanol per 1 g of Spirulina biomass and a volumetric productivity of 1.4 g of ethanol L-1 h(-1). Therefore, we conclude that it is possible, in a short time, to obtain a high ethanol yield corresponding to 160 L per ton of dry biomass with a high productivity.