Table 4.

One copy of comX is sufficient and required for transformation

StrainRelevant genotypeCloneCompetencea(Novr transformants/μl)
Expt 1Expt 2Expt 3
CP1250WT8307701,560
CPM2ΔcomX1 comX2 + 14005401,480
22,000
3570
CPM5 comX1+ΔcomX2 8101,350
CPM8ΔcomX1 ΔcomX2 <0.01b <0.01
CPM4ΔcomX1 comX2 1<1
2<1
  • a Several independent clones of each strain were grown in CAT containing 6 mM HCl to an OD550 of 0.025 in several experiments. 5MC (Novr) DNA was added to 10 μg/ml with CSP and NaOH. Incubation was continued for 40 min. Competence was measured as the number of Novr transformants in 1 μl (105 cells) of transformed culture except for CPM8, where it was measured in 100 μl of the culture. Where transformants were observed, at least 100 colonies were counted.

  • b No transformants were observed when the designated portion of culture was challenged.