Abstract: Object: To make protoplast and regenerate from Streptococcus thermophillus and Lactobacillus bulgaricus. The factors are consided that the protoplast are formed with the fungus age, the enzyme density, between the enzymolysis time and the enzymolysis temperature. To select the better conditions of the protoplast production with four factors three levels of the orthogonal test method. Results: The optimum conditions of the Streptococcus thermophilus are as follows: 16 hours of incubation times, concentration of lysozyme 1mg/ml, the hydrolyzing temprature 42℃, treating time 40 minutes. Under the optimum conditions, the ratio of formation protoplast are 98.75%, the ratio of regeneration are 23.8%; and the Lactobacillus bulgaricus are as follows: 16 hours, 10mg/ml, 36℃, 30min, 82.05%, 27.1%.Conclusion: The technique of this article could provide the effective data to genetic engineer and its protoplast fusion of the two bacteria.

Key words:  , Streptococcus thermophilus； Lactobacillus bulgaricus； potoplast； regeneration；