Using Polymicrobial Interactions to Identify Possible Novel Targets in Staphylococcus, Bacillus, and Candida

Microbes all compete for the same limited nutrients, space, and resources; therefore, they show competitive relationships. There is a component of Alcaligenes faecalis that inhibits the growth of Staphylococcus aureus, a gram-positive bacterium that causes many clinical diseases. We are interested in finding what genetic factors in Alcaligenes faecalis are responsible for killing Staphylococcus aureus. Transposon mutagenesis was used to interrupt certain gene segments by introducing a foreign piece of DNA into the Alcaligenes faecalis genome. By creating mutants of Alcaligenes faecalis, we were able to test these against Staphylococcus aureus to find those that can no longer inhibit. The absence of zones of inhibition indicated that we successfully interrupted the genetic element in Alcaligenes faecalis that kills Staphylococcus aureus. The genome of the mutants that presented no zones of inhibition were isolated to perform RACE PCR. After completing RACE PCR, the mutants were visualized using gel electrophoresis, and they were sequenced. In the sequence, we discovered that the gene that was being interrupted was 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