ELECTROPORATION AT ELEVATED-TEMPERATURES SUBSTANTIALLY IMPROVES TRANSFORMATION EFFICIENCY OF SLOW-GROWING MYCOBACTERIA

The effects of electroporation temperature, biochemical pretreatment o f cells and stage of culture on electroporation efficiency for slow-gr owing mycobacteria were investigated. The efficiency of transformation into Mycobacterium tuberculosis, Mycobacterium bovis and Mycobacteriu m intracellulare increased markedly with temperature. In contrast, the efficiency of transformation into Mycobacterium smegmatis, a fast-gro wing species, was higher at 0 degrees C and decreased with temperature . While stage of culture had little effect, a further increase in effi ciency of 2-4-fold was obtained following glycine or ethionamide pretr eatment. Electroporation at 37 degrees C has been chosen as a standard condition for slow-growing species as it usually resulted in a transf ormation efficiency several orders of magnitude higher than that obtai ned at 0 degrees C.