The ability of transformation in any given bacterial is dependent on the competence of the recipient strain. The competence state requires genetic information for the biosynthesis of competence factor and special physiological conditions.
Competent
cells of B. subtilis BD224, B. subtilis 110 and B. amyloliquefaciens K-10 were used recipient cells in heterologous plasmid transformation, although the transformation frequency was lower than that of the other B. subtilis strains.
The
optimal conditions for transformation were obtained by 3 hr of incubation in growth medium, 30 min in competence medium at 30℃, and 20 min contact of DNA at pH values between 7.0 and 7.5. In competent cells, the frequency of transformation
was in
the range of 1.6×10-5 to 7.2×10-5. On the other hand, transformation by plasmid DNA was improved by the use of protoplasts in PEG solution. Thus, this work reported a procedure for polythylene glycol induced protoplast
transformation
by
heterologous plasmid DNA. Basterial protoplasts were obtained by the treatment of cells with 10mg/ml lysozyme in SMM buffer. Lysozyme-generated protoplasts allowed uptake of TerR plasmid DNA in the pressence of PEG (MW 6000, 40%). In this
case
the transformation frequency was in the range of 1.5×10-3 to 2.2×10-2.
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