Methodologies to increase the transformation efficiencies and the range of bacteria that can be transformed
Electroporation allowed transformation of intact cells ofBrevibacterium flavum MJ-233. The two plasmids used for electroporation were pCRY2 (6.3 kilobases) and pCRY3 (8.2 kilobases). Both plasmids contain the chloramphenicol-resistance gene and the autonomous replication origin inB. flavum MJ-233. The efficiency of electrotransformation was optimal with cells harvested at the middle log phase of growth, and was imporved by the addition of 1.0U/ml of penicillin G to the culture medium. The optimum yield of transformants per μg DNA was 5×104 when the cell suspension was pulsed at a cell density of 1×1010/ml and at a DNA amount of 1.0μg.