Optimization and Comparison of Different Methods and Factors for Efficient Transformation of Brucella abortus RB51strain

BACKGROUND: The development of protective vaccines for Brucella spp. has been hampered by the difficulty in transformation of Brucella cells with foreign DNA for genetic manipulation. It seems that the formation of Brucella spheroplasts would increase the efficiency of transformation. The aim of this study was to devise an efficient method for the transformation of Brucella spp. MATERIALS AND METHODS: At first, spheroplast of Brucella was prepared by glycine and ampicillin induction and transformed using optimized protocols of CaCl(2), electroporation, and lipofection methods. Then, the efficacy of transformation was compared between the three-mentioned methods. RESULTS: Ampicillin-induced spheroplasts from early-log phase culture of brucella when incubated in a medium-containing 0.2 M sucrose during cell recovery had higher transformation efficiency in three different methods. Comparison of the transformation efficiency of Brucella abortus RB51 using the CaCl(2), lipofection, and electroporation methods revealed that the transformation efficiency with the lipofection method was significantly higher than with other two methods (P < 0.05). CONCLUSIONS: Lipofection method by lipofectamine 2000 on ampicillin-induced spheroplasts can be a suitable approach for Brucella transformation.