The Effect of Interspecies Signaling on Stenotrophomonas maltophilia Growth Zachary Dickinson May 2016Cystic fibrosis (CF) is a genetic disorder that effects over 70,000 people worldwide, and is particularly prevalent in those of Caucasian descent. CF increases susceptibility to chronic infections of the lungs and GI tract, often leading to decreased quality of life and early death to afflicted individuals. No cure is available, and so treatment is limited to treating the frequent infections that afflict CF patients. Several species of bacteria are commonly implicated in these infections, including Stenotrophomonas maltophilia. Infections of this species is of particular interest as it has been shown to be highly antibiotic resistant. This is a concern when it is part of coinfections with other, more virulent species, such as Pseudomonas aeruginosa. It has been shown that these two species are much more difficult to treat when they are present together than either one is alone.There is thought to be a molecular signaling mechanism through which these two species are able to communicate and increase each other's resilience, although the exact identity of that mechanism is unknown. This study began by identifying (based on bioinformatics) six likely candidates for quorum sensing receptor proteins. Through insertional interruption, five of these genes were made nonfunctional and these constructs were tested to identify a growth phenotype of S. maltophilia in the presence and absence of P. aeruginosa. Results of this study may suggest that none of the selected gene products play a role in communication between these two species, but additional assays may identify a connection.iv