| Congresso Brasileiro de Microbiologia 2023 | Resumo: 88-1 | ||||
Resumo:Endolysins are phage enzymes that catalyze the cleavage of peptidoglycan. These enzymes are synthesized by bacterial cells infected by phages, viruses that infect bacteria, at the end of the lytic cycle of infection. The result of their enzymatic activity is the hydrolysis of the murein layer, osmotic lysis of the cell, and release of newly synthesized phages. Therefore, the use of phages to inactivate bacteria and the use of purified endolysins have garnered interest in pathogen control. Previous studies have demonstrated that exogenously applied endolysins reduce bacterial growth, exerting either a bacteriostatic or bactericidal effect, similar to phages. However, the use of these enzymes is limited against Gram-negative bacteria due to the presence of an outer membrane. Our research group has identified an endolysin with a transmembrane domain in the N-terminal region, known as signal-anchor-release (SAR), which suggests action against Gram-negative bacteria. Salmonella enterica is an intestinal bacterium transmitted through the ingestion of contaminated water and food, causing systemic infections. Antibiotic resistance in S. enterica is a serious health problem, particularly its multidrug resistance. In several countries, strains producing extended-spectrum β-lactamases (ESBLs) have already been found in animals intended for human consumption. Thus, the present study evaluated the in vitro antimicrobial activity of the endolysin LysKpV475 (YP_009280719.1) combined with the Salmonella phage phSE-5 (KX015771) against Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311. The assay was conducted in 96-well plates, where each well was inoculated with the bacterial suspension (final concentration of 105 CFU/mL), endolysins, and/or phages. The plates were then incubated at 37 °C, and spectrophotometric readings at OD λ=600nm were taken for 48 hours to quantify bacterial growth. The results are represented in Figure 1.
The phage assay demonstrated a decrease in bacterial growth, as seen comparing the bacterial control curve (●) and phage (MOI=100) curve (▼). Similarly, the endolysin at the inhibitory concentration (300 µg/mL) (⬣) also showed a decrease in bacterial growth. A greater inactivation was observed when the phage and endolysin were used, as shown in the growth curve of bacteria treated with a sub-inhibitory concentration of the endolysin (200 µg/mL) and phage (MOI=100) (○), which resulted in inhibition of bacterial growth to the detection limit of the method. These results provide new perspectives for the combined application of endolysin and phages as an effective antibacterial approach against pathogenic bacteria.
FUNDING AGENCY: SÃO PAULO RESEARCH FOUNDATION - FAPESP (FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO). Palavras-chave: Endolisyns, Bacteriophages, Phage treatment, Synergy, Salmonella enterica Agência de fomento:Fapesp | |||||