Method for producing fatty acid ester

#The present invention relates to a method of producing a fatty acid ester.

#In recent years, with a growing consciousness of and a growing interest in environmental issues such as global warming, reduction of carbon dioxide emissions and reduction of a concentration of carbon dioxide in air by fixation of carbon dioxide have been great challenges. Therefore, attempts to break dependence on fossil fuels and to actively utilize a biomass, which is a carbon neutral source, as an energy source have been made actively.

#For example, Euglena is known as an alga producing a lipid or the like in the cells. With focusing attention on lipid productivity thereof, there has been proposed a method involving: culturing Euglena aerobically; then placing the resultant under an anaerobic condition to convert a storage polysaccharide paramylon into a wax ester; physically breaking the resultant; and then isolating the wax ester by centrifugation, solvent extraction or the like (Patent Document 1). Further, there is known a method involving: heating and pressurizing Euglena using an autoclave; allowing a high concentration of a protease to act on the Euglena; and fractionating a water-soluble component by filtration. However, fractionation of a water-insoluble component has not been examined (Patent Document 2).

#The inventors of the present invention tried to subject Euglena to physical crushing or treatment with a high concentration of protease to fractionate a water-insoluble fatty acid ester taken out of the cells of the Euglena, and found that it was difficult to improve the yield of the fatty acid ester, and, in particular, that the yield of the fatty acid ester was significantly lowered in the case of allowing a high concentration of protease to act on the Euglena.

#Therefore, the present invention relates to providing a method of producing a fatty acid ester in a high yield through a simple operation using Euglena as a material.

#The inventors of the present invention made studies to achieve the above-mentioned object, and as a result, surprisingly found that when a protease was allowed to act on Euglena in a much smaller amount than ever before, a fatty acid ester was able to be collected from the Euglena in a high yield.