Preparation of Serum-free Medium by MA₁₂ Bacterial Synergist and its Application I.Effect of MA₁₂ Bacterial Synergist on Increasing the Amount of Pasteurella multacida of Fowl Cholera in Sorum-free Medium

One kind of growth-stimulating factor, 12 which has an obvious bacterium-increasing effect had been prepared.Adding 0.05-0.15% MA12 to the culture growing Pasteurella multacida of Fowl Cholera has similar effect on increasing bacterial amount to compare with adding 3-5% animal serum in the culture.The cell capsule antigen prepared with serum-free culture has good immunity for poultry.MA12 is mainly consisted of plant growth-regulating substrate and microelements.It is easy to be gathered with low cost and convinient use,also can be sterilized by autoclave.This is the first report on using scrum-free medium to produce capsule subunit vaccine in China.