Production and purification of endolysins from Salmonella bacteriophages

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2023-7-19
Yetişkin, Segâh
Salmonella is one of the major bacteria causing foodborne diseases in the world. Salmonella is Gram-negative, non-spore forming and rod shape bacteria, and those with enteric fever and non-typhoidal salmonellosis cause gastroenteritis problems. Antibiotic resistance is a problem that threatens the whole world in recent years, and bacteriophages come first as a novel method. Bacteriophages are the viruses that infect bacterial cells. Bacteriophages are used against antibiotic resistance, but their use is limited because they are not reproducible. Using their burst mechanisms, endolysins can be used instead of bacteriophages. Endolysins, bacteriophage lytic enzymes, are enzymes produced during growth of bacteriophage in the cell. Endolysins cause cell death by disturbing cell wall and cell membrane of the bacteria and to release new forming viruses. Endolysins may be suitable for food applications because they are more sustainable and more stable to changes in pH and temperature. In this study, bacteriophage (MET P1- 137), isolated from our previous study, was used which can infect multi-drug resistant Salmonella Kentucky (MET S1-007). By analyzing genome of the phage (MET P1- 137), regions producing endolysins were selected. By using a plasmid vector, the encoding gene of endolysin was transferred to E. coli BL21 strain. After microbial growth, purification of endolysin was conducted and lytic activity of the endolysin on Salmonella Kentucky was investigated. As a result, it was observed that presence of purified endolysin reduced Salmonella Kentucky cells by 1 log CFU / mL. Future research will examine external parameters such ideal pH and temperature to increase concentration of endolysin, interactions with metal ions, and the permeability effects of organic acids on the outer membrane. Food applications will also be tested.
Citation Formats
S. Yetişkin, “Production and purification of endolysins from Salmonella bacteriophages,” M.S. - Master of Science, Middle East Technical University, 2023.