Screening And Fermentation Optimization Of The Strain To Digesting Free-gossypol

Cottonseed cake is produced by pressing cottonseeds. And it can be a kind of ideal protein fodder, because it is rich in high-quality vegetable proteins. When used in China, a country lack of coarse fodder, to some extent, cottonseed cake can make up the resources. However, there is a poisonous substance called free gossypol included in cottonseed cake, which can cause cattle’s toxicosis even death in a long term without detoxification treatment, resulting in tremendous economic losses to the raisers. So it is significant to detoxicate the cottonseed cakes for the sake of a much safer and more efficient livestock industry.So far the biological fermentation is considered the safest, effectual detoxification method with low cost. The detoxification technology of microorganism solid state fermentation covers many advantages, such as high toxic-free rate, shorter period, less investment, simpler technics, pollution-free and low cost, etc. And the microorganism active metabolite produced during fermentation is an incommensurable merit, which can transform fibrin into valuable mycoprotein, and improve the nutrition and palatability. Therefore, the detoxification technology of microorganism solid state fermentation is of high potential and broad prospects.To increase the concentration of F-1fermentation liquid for gossypol degradation strains, we optimized the fermentation conditions. Single-factor test and orthogonal experiment method indicated that the best carbon source was sucrose, the best nitrogen source was beef extract and the best inorganic salt was MgS04-7H2O and FeCl3, the optimum fermentation medium and optimum fermentation conditions for concentration production of F-1strains as following:sucrose0.5%, beef extract5%, FeCl30.1%, MgSO4·7H2O0.05%, NaH2PO4·H2O0.03%, K2HPO40.05%, MnSO4·H2O0.02%. The optimum fermentation conditions were:original pH value was7.2, volume was50mL/250mL, inoculation amount was4%, rotate speed was220r/min and fermentation temperature was37℃. After optimization, the concentration production of F-1was improved to2.6×109cfu/mL. Spore production rate was up95%. It established foundation for further research and application.To get further study of the detoxification effect, we conducted a study of fermentation conditions of cottonseed, By single factor and orthogonal test method, the optimum fermentation medium as following:carbon source was corn flour, proportion of materials and water was1:0.6, inoculation amount was5%, The proportion of cottonseed and corn flour was7:3,(NH4)2SO4was2%, fermentation temperature was37℃, fermentation time was ten days. In this fermentation process conditions can achieve better detoxification effect, gossypol degradation rate can reach82.41%.Assessing the nutrient contents of cottonseed cakes after inoculation and fermentation, is to obtain how bacterial strains can change the nutrient contents, what’s more, to have a better understanding of the value of using cottonseed cakes.To test security of strain F-1, the fermentation liquid was feed to mice. We didn’t found any pathological changes in viscera and intestine, so strain F-1was safety Bacillus subtilis. To get further study of the detoxification effect, the cottonseed cakes were applied to mice, also causing no pathological changes to the viscera and enteric canals. Therefore, F-1bacterial strains can greatly reduce the harm to cattle caused by free gossypol.