Preparation Of Nattokinase And Its Resistance To Staphylococcus Aureus By Solid State Fermentation Of Oil Meal Of Xanthoceras Sorbifolia Bunge

The oil meal of Xanthoceras sorbifolia Bunge is a by-product of the seeds cold-pressed.It is rich in active substances.With the expansion of the planting area of Xanthoceras sorbifolia Bunge,the total yield of oil meal is larger,but it is not used efficiently.The product has a low comprehensive utilization value.but it is currently only used for crude products such as feed,and the added value is extremely low.In order to fully develop and utilize oil meal of sorbifolia and increase its added value,this study prepared nattokinase from the base of fermentation medium,and carried out a series of studies on the isolation,purification and bacteriostasis of nattokinase.The research results are as follows:(1)The optimal process conditions for the preparation of nattokinase by solid state fermentation of oil meal of Xanthoceras sorbifolia Bunge the mass ratio of oil meal and bagasse is 4:1,and the available carbon and nitrogen sources and inorganic salts are xylose,ammonium sulfate and magnesium sulfate,respectively,their amounts are 1.9%?1.3%?0.3%,the initial feed water ratio was 1:2,the inoculum of Bacillus natto was 11.63%,and the fermentation was carried out at 23 ?-37? for 56 h.Under the above conditions,the activity of the nattokinase obtained by the experiment was 1114.80 U/mL,and the obtained nattokinase activity was improved by about 60.8%compared with the optimization before;(2)Process conditions for separation and purification of nattokinase by three-phase separation of solid state fermentation products:This study obtains the optimal separation conditions by single factor experiment,that is,adding ammonium sulfate to saturation degree 60%at a temperature of 25? to 37? and a system pH of 8.0.And then the t-butanol with a volume ratio of 1.5:1 was thoroughly mixed with the crude enzyme solution.Under the above conditions,the activity of the nattokinase isolated and purified reached 3574.28 U/mL,and the purification ratio was 4.8 and the recovery was 25.66%.This indicates that the oil meal of Xanthoceras sorbifolia Bunge is completely suitable for the preparation of nattokinase as a medium for Bacillus natto,and the solid fermentation product can obtain nattokinasewith high activity,purification ratio and high recovery by three-phase separation method,and the operation is simple,low cost,which opens up a new way for the efficient use of nattokinase.(3)Inhibition of nattokinase against Staphylococcus aureus by separation and purification of solid fermentation products:it is known that in the initial stage of growth of Staphylococcus aureus,it is also the first stage of biofilm formation,that is,the stage of cell adhesion.Nattokinase has the strongest inhibitory effect on Staphylococcus aureus,especially when compared with the bacteriostatic effect of nattokinase alone,the bacteriostatic effect of nattokinase combined with antibiotics(vancomycin,rifampicin)is more significant,which provides a new idea for the treatment of infection of Staphylococcus aureus infection.