Effective plasmid delivery to a plasmid-free Bacillus natto strain by a conjugational transfer system

In this study, a Bacillus natto strain named NEST141 was constructed. The strain carries no plasmids and is an authentic proline auxotroph-a feature that confers effective selection conditions for plasmids transferred from a donor, such as Bacillus subtilis 168, via a pLS20-based conjugational transfer system. We have provided a standard effective protocol for the delivery of plasmids larger than 50 kilobase pairs. These results indicate that the B. natto NEST141 strain can become a standard model, like B. subtilis 168, for extensive genetic engineering with diverse applications.