适于德氏乳杆菌保加利亚亚种质粒抽提的混合培养基

The mixed medium suitable for the extraction of plasmid from Lactobacillus delbrueckii subsp.bulgaricus

目的探讨适合提取德氏乳杆菌保加利亚亚种质粒的细菌培养基。方法配制含不同比例MRS的营养肉汤混合培养基,进行德氏乳杆菌保加利亚亚种的培养,通过生长曲线测定、细菌形态观察,菌体内天然质粒抽提质量等来确定适于该菌质粒抽提的最佳混合培养基。结果单纯营养肉汤培养基不适合德氏乳杆菌保加利亚亚种的增殖,在含20%、40%、60%及80%MRS的营养肉汤混合培养基中该菌的生长曲线与在MRS中的基本一致,但细菌数略低;形态学检测表明含MRS的营养肉汤培养基培养对德氏乳杆菌保加利亚亚种的形态无影响,质粒抽提结果表明,本研究所配制的几种含不同比例MRS的营养肉汤混合培养基中,含20%MRS的营养肉汤混合培养基最适合该菌质粒的抽提,提取的质粒浓度高,质量好。结论本实验制备的混合培养基中,含20%MRS的营养肉汤混合培养基能保证德氏乳杆菌保加利亚亚种的正常增殖,而且可能由于产生较少的胞外多糖,使溶菌酶更易水解该菌细胞壁肽聚糖,最适于该菌质粒的抽提。

Objective To explore the optimal mixed medium for the extraction of plasmid from Lactobacillus delbrueckii subsp, bulgaricus. Methods Nutrient broth media containing different ratios of MRS were prepared, and the optimal mixed medium for extracting plasmid from Lactobacillus delbrueckii subsp, bulgaricus was determined by means of bacterial growth curve determination, bacterial morphology, and the concentration and quality of the natural plasmid extracted from this bacteri- um. Results Nutrient broth alone was not suitable for the proliferation of Lactobacillus delbrueckii subsp, bulgaricus, but the growth curves of the bacteria cultured in nutrient broth containing 20 %, 40 %, 60 % and 80 % MRS were consistent with the bacterial growth curve in MRS, and the number of bacteria in nutrient broth containing MRS was slightly lower than that in MRS alone. Morphological analysis showed that the bacteria cultured in nutrient broth containing MRS had no effect on the mor- phous of LactobaciUus delbrueckii subsp, bulgaricus, and the results of plasmid extraction showed that among the mixed media prepared in this study, plasmid with high yield and purity could be extracted from bacteria cultured in nutrient broth containing 20 % MRS. Conclusions Lactobacillus delbrueckii subsp, bulgaricus can proliferate normally in nutrient broth containing 20 % MRS and peptidoglycan in cell wall of the bacteria cultured in this mixed medium can be easily hydrolyzed by lysozyme due to less production of extracellular polysaccharide, so this mixed medium is very suitable for the plasmid extraction from this bacte-rium.