The invention provides a method for preparing
ethanol by adding Mn (II) salt for promoting simultaneous saccharification and
fermentation of
straw. The method comprises the steps of: after
grinding and sieving
straw stalks, selecting glycol as a liquefier, carrying out
liquefaction pretreatment under the
catalysis action of concentrated
sulfuric acid, and carrying out washing and suction
filtration to obtain a
fermentation substrate; selecting pachysolen tannophilus and
saccharomyces cerevisiae as
fermentation microorganisms, respectively taking the two types of
yeast after slant culture and activating in a YEPD (
Yeast Extract Peptone Dextrose)
liquid culture medium, loading a culture medium mixed liquor by using a hemocytometer, determining the
yeast concentration through microscopic counting, and diluting to suitable concentration; respectively adding the fermentation substrate, a MnSO4 solution,
cellulase and the diluted
yeast mixed liquor into a fermentation tank, and after adjusting to a suitable
solid-liquid
mass ratio by using
sterile water, carrying out simultaneous saccharification and fermentation under the condition of constant temperature; finally determining the
ethanol concentration in fermentation liquor by using a spectrophotometric method, and calculating to obtain the final yield of the
ethanol. According to the method, the related raw materials are wide in sources, and the method is convenient to operate, and can be used for reducing the dosage of the
cellulase so as to lower the process cost and starting biochemical reaction at low temperatures, thus providing a new
train of thought for a production process in the field.