The invention discloses a preparation method of
biodiesel and compound
enzyme used by the method. The method comprises the following steps of: adding short-chain
alcohol, oil, water and the compound
enzyme into a reaction vessel, controlling the temperature at 30-50 DEG C, and reacting for 48-72hours to prepare the
biodiesel, wherein the
molar ratio of the short-chain
alcohol to the oil is (3-5): 1, the use level of the water is 40-100% as heavy as that of the oil, and the use level of the compound
enzyme is 4-22U / g of
soybean oil. The method is environment-friendly without adding any organic solvents, can express the compound enzyme by utilizing recombinant
bacteria, does not need to purchase the commercial enzyme, and the compound
lipase is adopted to cooperatively catalyze, so that the
substrate specificity of single
lipase can be overcome, the ester converting efficiency when the
biodiesel is prepared by an
enzyme method can be improved, and products are easy to separate. After the method for
catalysis by using the compound
lipase is used, the use level of the required enzyme is reused by more than 50% of the use level of the single lipase, and the yield of the active ingredients in the biodiesel, i.e., the
fatty acid methyl ester, is 98%, so that the production cost can be greatly reduced. The preparation method is very good in industrialized prospect.