Lytic Activity of Endolysins PlyP56 and PlyG

Abstract

This study examines the lytic activity of the phage-encoded endolysins PlyP56 and PlyG against the bacterium Bacillus cereus. These endolysins, which are proteins that contain a cell wall-binding domain and an enzymatic lytic domain, target the peptidoglycan wall of bacteria, ultimately leading to cell lysis. To characterize these proteins, they were first cloned into an expression vector with a 6x-histidine tag. We then induced protein expression and purified each protein on a Ni-NTA resin. SDS-PAGE was used to verify the successful purification of both endolysins. A Western blot was performed to further verify purification, demonstrating clear bands corresponding to both endolysins. After purification, a plate reader was used to measure B. cereus cell lysis over time, after treatment with either PlyP56 or PlyG. The results demonstrated that PlyP56 and PlyG both had lytic activity against B. cereus. This research is important because B. cereus is closely related to Bacillus anthracis, which causes the deadly disease anthrax. Endolysins could be used as a potential alternative to traditional antibiotics in treating bacterial infections, which is especially important due to the increase in antibiotic resistance. Other studies have validated the clinical applications of endolysins and demonstrated that engineered endolysins are more effective than the wild-type endolysins that were used in this study. Future studies should be done to further validate the lytic activity of the endolysins through methods such as direct plate counting. Additionally, future studies could be done to determine the additive effects of PlyP56 and PlyG against B. Cereus.