Pre-screening study on freeze-drying protectants for Mycoplasma bovis
In order to explore the effective protective substances for freeze-drying Mycoplasma bovis(M.bovis),this study employed a four-factor,four-level orthogonal design experiment alongside a single-factor experiment.The effects of skim milk,sucrose,mannitol,glucan,trehalose,urea,BSA,lysine,and other substances on the survival rate of M.bovis were detected by measuring the number of the live M.bovis HB150 post freeze-drying and the optimal concentrations and ratios of the different protective agents were ultimately established.The ratios of the main and auxiliary components of the freeze-drying protec-tants were determined through orthogonal design experiments,and the final ratios of the lyophilized protec-tants were as follows:15%skimmed milk,4.0%sucrose,4.0%mannitol,3.0%glucan,2.0%alginate,1.5%urea,1.0%BSA,and 0.3%lysine.When freeze-drying at-40℃and 12 Pa for 20 h,this formula-tion maintained the highest activity rate of M.bovis,reaching(55.2±2.1)%.The results indicated that the selected dynamic dry protectants exhibited a strong protective effect and could be effectively applied in the actual freeze-drying process of M.bovis.
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