Optimization Of Fermentation Conditions For Exopolysaccharide Production By Bacillus Licheniformis SN02004-01 And Study On Hypoglycemic Activity

Bacillus licheniformis is a kind of intestinal probiotics,which is rich in secondary metabolites such as extracellular polysaccharides and proteases.Research in recent years has shown that microbial polysaccharides have good biological activity,but there has been little attention and reports on the synthesis of extracellular polysaccharides by Bacillus licheniformis.This experiment is based on the use of Bacillus licheniformis SN02004-01 as the fermentation strain to ferment the ultrafine Cordyceps militaris powder in the early stage of the laboratory and the preliminary exploration of its fermentation broth has hypoglycemic function on diabetic mouse models.Crude polysaccharides were extracted from the fermentation broth,and fermentation conditions were optimized,and the best single factor conditions were obtained:the concentration of Cordyceps militaris ultrafine powder was 2.5%,the inoculum was 3%,and the glucose addition was 0.4%.Through response surface model design and experiments,the optimal comprehensive fermentation conditions were determined as follows:Cordyceps militaris ultrafine powder concentration 2.96%,inoculation amount3.06%,and glucose addition amount 0.38%.The shake flask culture experiment and the fermentation tank culture experiment showed that the polysaccharide content in the fermentation broth was 5.4 mg/ml respectively.Crude polysaccharide ion exchange and molecular sieve chromatography were used to obtain a homogeneous polysaccharide component with a molecular weight of 1.9×10~7 Da,mainly composed of Gal,Man and Glu,with a molar ratio of approximately 1:3.24:4.56.Animal experiments show that the extracellular polysaccharide has a relieving effect on the abnormalities of body weight,glucose tolerance and blood sugar level of diabetic mice.At the same time,it can regulate the MDA,NO and insulin in the blood and kidney of diabetic mice,thereby regulating metabolic abnormalities caused by elevated blood sugar to a certain extent,and controlling the symptoms of diabetes.In order to prove that this type of polysaccharide has The role of blood sugar control and prevention of complications provides a theoretical basis.