Study On The Swine Streptococcus Septicus Vaccine Fermentation And Its Freeze-drying Process

In this study, production technology of swine Streptococcus septicus vaccinestrain (ST171) was optimized, including fermentation condition and freeze-dryingtechnology.The optimization of medium and culture conditions for St171fermentation werestudied. Four kinds of medium were used for fermentation of swine Streptococcussepticus vaccine strain (ST171), and the results indicating that Martin media wasbenefit for culture of this strain. The effects of initial glucose concentration,supplement concentration of serum, and culture time of ST171fermentation were alsoinestigated.And then, the appropriate rates of agitation and aeration were selected, and somemeasures were applied to decrease the accumulation of lactate in cultivation of ST171.Under optimization conditions, the viable count of ST171increased to6.0×10~9CFU/ml that increased by30%compared with that of initial culture condition, whichsupplied theoretical basis and experiment evidence for large scale production of swineStreptococcus septicus vaccine strain (ST171).Lactate is a primary inhibitory metabolite in ST171cultivation, and the measuresto decrease excretion of lacetate was studied. Many kinds of feeding strategy weredeveloped in ST171fermentation, and the results showed that constant feedingmethod could prolong the stabilize period of ST171.Freeze-drying was a key process for production of ST171vaccine, and it wasoptimized in this study. A appropriate freezen curved-line was obtained, and thelyophilized rate increased from50%to80%. To and above100head a/bottle obtainedby2.5ml fermentation broth per bottle, and the ageing resistance of that was alsoinvestigated. The effect of cryoprotectant on viable count in the freeze-dried vaccinewas also studied in this study.