Incorporation of the whole chromosomal DNA in protoplast lysates into competent cells of Bacillus subtilis

Competent cells of Bacillus subtilis AC870 (pul B, leuB, trpC, ald-1) were transformed to Ade(+), Trp(+), or Ade(+) Trp(+) with DNA in protoplast lysa tes of B. subtilis AC819 (hisH, tet-1, rpsL, smo-1). The cotransfer ratio o f purB to trpC was constant at 7-9% (Ade(+) Trp(+)/Trp(+)) or 3% (Ade(+) Tr p(+)/Ade(+)) at protoplast concentrations of 2.7x10(3)similar to2.7x10(6) p er ml, The whole chromosomal DNA must be certainly incorporated into compet ent cells from the following reasons; (1) purB is opposite to trpC on the c hromosome, (2) 2.7 x 10(3) protoplasts per mi is about 100 times lower than 3.2 x 10(5) competent cells per mil, and (3) the cotransfer ratio is const ant at ail the concentrations, Similar results were obtained with the cotra nsfer ratio of purA to trpC. The transformation requires several Com protei ns including ComK.