Wild type Bacillus subtilis strains are often characterized by lower natural competence or non-competence for DNA uptake. To study such strains, it is necessary to develop genetic manipulation tools that allow us to achieve insertion of the desired DNA segments. One of the ways to produce recombinant strains is the electroporation method, which we studied in our master's thesis. We performed experiments to optimize the method by testing different ways of preparing electrocompetent cells and electroporation parameters. Initial experiments to electroporate naturally competent B. subtilis strains 168 trpC2 and PS-216 were both successful, but electroporation of naturally noncompetent strains proved to be extremely difficult as we could not achieve the optimization of the method. To proceed with the planned experiments, we introduced the method of preparing recombinant strains by phage transduction. We succeeded in producing mutants of naturally non-competent strains, which we then used to study DNA exchange between differentially related strains during swarming on semisolid B media. Strains were labelled with an antibiotic resistance gene and a fluorescent marker. We tested DNA transfer between three combinations of non-kin strains and between one isogenic combination. Increased DNA transfer occurred between one of the tested non-kin combinations. No DNA transfer occurred in the isogenic combination. The result suggests the possibility of increased horizontal gene transfer between strains due to kin discrimination and the consequent induction of competence in otherwise naturally non-competent strains.
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