Using Transposon Mutagenesis to Discover Novel Polymicrobial Therapeutic Targets

Microbes compete for the same limited nutrients, space, and resources; therefore, they show competitive relationships. Our laboratory has previously shown that Alcaligenes inhibits the growth of Staphylococcus, a Gram-positive bacterium, and Candida, a fungi, which are both substantial causes of human infections. We are interested in determining the genetic factors in Alcaligenes that are responsible for killing these competitors. Transposon mutagenesis was used to interrupt gene segments by introducing a foreign piece of DNA into the Alcaligenes genome. By creating these mutants of Alcaligenes, we were able to screen these against Staphylococcus to find those that can no longer inhibit. The absence of zones of inhibition indicated that we successfully interrupted the genetic element in Alcaligenes that kills Staphylococcus. The genome of the mutants were isolated and the area disrupted was sequenced. In one mutant, we discovered that the gene being interrupted was a MFS transporter. This is an important transporter in bacteria for virulence, metabolism, and quorum sensing. Results from this study may help us find new targets for Staphylococcus aureus infections