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Abstract
Acinetobacter baylyi ADP1is a naturally competent, non-pathogenic soil bacterium used for the study of natural transformation. Natural transformation is the ability to acquire extracellular DNA and use that DNA as new genetic material. Here, we tested the impact of monovalent cations on transformation efficiency by comparing transformation using LB agar, which contains Na+ ions, to transformation using LBK agar, which contains instead K+ ions. We found no difference in transformation efficiencies using these two types of solid media during transformation. Next, we intended to test the effects of divalent cations on transformation efficiency. But, rates of transformation were so high on both LB and LBK that we first needed to find conditions under which transformation efficiency was <0.1% in order to be able to detect whether the addition of cations would have a positive effect on transformation efficiency. Thus, we reduced the amount of DNA used for transformation, but doing so did not reduce the transformation efficiency. Then, we altered the conditions under which we measured transformation efficiency by adding DNase, which degrades extracellular DNA, in order to restrict the time of DNA availability. However, these manipulations did not reduce the transformation efficiency either. Control experiments verified that the wild type, non-transformed cells were sensitive to the antibiotic chloramphenicol. This control is important because the donor DNA confers resistance to chloramphenicol. Unfortunately, the desired conditions of experimental room were never obtained, and thus a effective comparison of transformation rates due to divalent cation presence was conducted. We conclude that ADP1 cells are extremely competent under all conditions tested.