Screening, Optimization Of Fermentation Process And Application Of Gossypol Degradation Strain

Cottonseed cake is produced by pressing cottonseeds. and is an ideal protein feed , because it is rich in high-quality vegetable proteins. When used in China, a country lacking of coarse fodder, cottonseed cake can fulfill the need to some extend. However, there is a poisonous substance called free gossypol included in cottonseed cake, which can cause cattle’s toxicosis and even death in the long term without detoxification treatment, resulting in tremendous economic losses to the raisers. So it is important to detoxicate the cottonseed cakes for a much safer and more efficient livestock industry.So far biological fermentation is considered the safest, most effective detoxification method with a low cost. The detoxification technology of solids by fermentation using microorganism has many advantages, such as high toxic-free rate, shorter treatment period, less investment, simpler technics, pollution-free and low cost, etc. And the microorganism active metabolite produced by the microorganism during fermentation is an incommensurable merit, which can transform fibrin into valuable mycoprotein, and improve the nutrition and palatability. Therefore,detoxification technology of solids by fermentation using microorganism has much potential and broad application and development prospects.To increase the concentration of M-4 gossypol degradating strains in the fermentation liquid, we optimized fermentation condations. Single-factor test and orthogonal experiment method indicated that the best carbon source was sucrose, the best nitrogen source was peptone and the best inorganic salt was MgSO₄·7H₂O, the optimum fermentation medium and optimum fermentation conditions for increasing the production of M-4 strains is as follows: corn meal 5.0 g, earthnut flour 10.0 g, MnSO₄·H₂O 1.0 g, MgSO₄·7H₂O 0.5 g, CaCl₂·2H₂O 0.1 g, K₂HPO₄ 0.5 g,FeCl₃ 0.2 g. The optimum fermentation conditions were: original pH value was 8.0, volume was 120 mL/250 mL, inoculation amount was 2%, rotate speed was 220 r/min and formentation temperature was 30℃. After optimization, the concentration production of M-4 was improved to 2.6×10¹² cfu/g. Spore production rate was up 95%. This established the foundation for further research and application.Assessing the nutrient contents of cottonseed cakes after inoculation and fermentation, evaluates 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 the safety of strain M-4, the formentation liquid was feed to mice. We didn’t found any pathological changes in viscera and intestine, so strain M-4 was a safe strain of Bacillus subtilis subsp.subtilis.Safety tests that fed mice with zymotic fluid of M-4 bacterial strains, caused no pathological changes to the viscera and enteric canals. So it can be shown that the M-4 bacterial strain is a safe strain of Bacillus subtilis. To get further study of the detoxification effect, the cottonseed cakes were applied to mice and chickens, also causing no pathological changes to the viscera and enteric canals. Therefore, M-4 bacterial strains can greatly reduce the harm to cattle caused by free gossypol.