Application of refined cordyceps polysaccharides to preparation of medicament for resisting gram-negative plant pathogenic bacteria

The invention relates to the technical field of biology, in particular to a method for preparing refined polysaccharides with bacteriostatic activity through cordyceps culture, and application of therefined polysaccharides. The cordyceps culture is taken as a raw material to extract crude polysaccharides, proteins in the crude polysaccharides are removed through the means of combining a macroporous resin adsorption method and a Sevag method, and thus the refined polysaccharides are obtained. Then step-by-step ethanol precipitation is adopted to obtain 95% ethanol precipitation refined cordyceps polysaccharides CP95 which have the bacteriostatic activity on three types of gram-negative plant pathogenic bacteria. The preparation method has the characteristics of easy operation, stable performance and low cost, and the important economic significance for better developing and utilizing the cordyceps culture and lowering the clearing cost of a cordyceps waste culture medium is achieved. 本发明涉及生物技术领域，具体地，涉及一种利用虫草培养