Study On Optimization Of Solid-State Fermentation And Application Of Enterococcus Faecium

As a feed additive, antibiotics not only can prevent and cure of disease, but also can help the growth of animals. Chronic use of antibiotics raises questions about resistance, which is widely regarded by people. Many countries have already prohibited or restricted the use of antibiotics by law. To find a safty and nontoxic replacer is imperative. As a new-type feed additive, probiotic preparations are no toxic, residue-free and environment-friendly, which can help the growth of animals, prevent and cure of intestinal disease, improve feeding environment and facilitate the sustainable development of environmental protection industry and ecological farming industry. As a normal flora in animal intestines, the content of Enshine Enterococcus remaines constant in the intestinal microflora. Enterococcus remaines can keep animals under normal physiologic condition and help them grow because of the mutualitic association with other probiotics.The solid-state fermentation techniques of Enterococcus faecium were optimized in this paper. Then the process was scaled up. This paper also studied the properties of application such as heat resistance and storage property of Enterococcus faecium agent.The results in detail were as follows:1. The optimal fermentation technological conditions of solid-state fermentation for the stain Enterococcus faecium in cans bottles were obtained through the single element experiment. Enterococcus faecium was cultured for 36h at 37℃using 1mL seed (seed age 12h) and 20g wheat bran. The optimum fermentation medium was 20g wheat bran supplemented with 0.8g dipotassium hydrogen phosphate and 0.2g wheat protein with an initial moisture content of 50%. Then the viable count of Enterococcus faecium agent was 5.6×109CFU/g dry substrate.2. According to the optimal conditions as above, the fermentation process was scaled up to pilot batch sizes using three different sizes of fermenting tanks. The viable count of the Enterococcus faecium agent was 7.2×109CFU/g, in 2L fermenting tank with 250g ferment medium. Then the viable count of the Enterococcus faecium agent was 6.45×10 CFU/g, in 34L fermenting tank with 5.5kg ferment medium. Finally Enterococcus faecium was cultured 170L fermenting tank with 25kg ferment medium. The viable count of the Enterococcus faecium agent was 6.8×109CFU/g, increased by 21.4% that compared to laboratory scale in cans bottles. 3. We studied the properties of application such as heat resistance and storage property of Enterococcus faecium agent, then found that the survival rate of Enterococcus faecium was 76.76% and 84,87%, after Enterococcus faecium agent with an initial moisture content of 18% had been controlled at 90℃for 2min and 100℃for lmin respectively. By keeping the moisture content of Enterococcus faecium agent at 6%-8%, the survival rate of Enterococcus faecium remained between 68.44% and 75.08% after storage for 8 weeks at 28℃.