(Georgia Institute of Technology, 2020-12)
Butler, James H.
Biofilms are a specialized structural formation that some bacterial species form when growing in certain environments. One such environment is the human lung, where the bacteria Pseudomonas aeruginosa forms biofilms that infect the lungs of cystic fibrosis patients. Techniques used to destroy biofilms have been studied previously, and one promising technique involves the use of bacteriophage. Phage are small, bacteria-targeting viruses that when introduced to biofilms cause the lysis, or destruction of bacterial cells and in some cases, the subsequent destruction of the biofilm. While the impact of phages on biofilms is well known, the changes in physical properties such as extracellular polymeric substance (EPS) distribution and pH distribution in biofilms treated with phage has not been examined in detail. This study seeks to establish pH distribution in Pseudomonas aeruginosa biofilms using confocal microscopy and the pH sensitive molecular probe CSNARF4, as well as SYPRO ruby biofilm for the staining of all EPS proteins. Both phage-treated and untreated biofilm samples with the separately added stains of CSNARF4 and SYPRO ruby biofilm matrix were imaged using confocal microscopy and evaluated with a microtiter plate reader, respectively. It was discovered that biofilms treated with phage exhibited little reduction in average pH across all depths into the biofilm, while there was a pronounced increase in protein release into the EPS upon cell death. These results provide greater insight into the effect phages have when being used to treat biofilms and elucidates points of improvement in biofilm treatment.