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Published on: July 22, 2011
Identify and characterize a carbapenem-resistant Salmonella enteritidis phage depolymerase Dpo52
Wei Li1, Mengyao Yuan1, Jiaxin Che1
1Department of Laboratory Medicine, Center for Infectious Diseases and Pathogen Biology, The First Hospital of Jilin University, Changchun, 130021, China.
Abstract:
Salmonella enteritidis, a gram-negative bacterium, is a common cause of human foodborne diseases. Multidrug-resistant strains are increasing year by year, especially the carbapenem resistant isolates. One of the reasons for antibiotic resistance is the formation of bacterial biofilm. But reports on phage depolymerases against carbapenem resistant S. enteritidis are scanty, which underlines the importance of the study. In this study, we characterized a phage that can infect carbapenem resistant S. enteritidis, vB_Sen_S3P. A phage was isolated from sewage water in Changchun, China, its genome was analyzed, and its depolymerases were expressed and purified. The host specificity and activity of the depolymerases were determined. The isolated carbapenem resistant S. enteritidis phage, vB_Sen_S3P, infects 22 out of 30 tested clinical isolates of S. enteritidis, including carbapenem-resistant S. enteritidis S25 and S27. The highest phage titer was observed at a multiplicity of infection of 10- 5 and a burst size of approximately 16,931 PFU/infection. Transmission electron microscope micrographs indicated that vB_Sen_S3P had an icosahedral head and a short non-shrinkable tail. Based on a comparative analysis, the complete genome of vB_Sen_S3P was 43,620 bp with a GC content of 49.76%. PSI-BLAST analysis indicated that ORF52 of vB_Sen_S3P (Dpo52) shares low identity (≤ 41.4%) with other reported Klebsiella phage depolymerases. Dpo52 was expressed and purified as a soluble protein using E. coli BL21. Dpo52 was stable at pH 4-11 and in a temperature range of 4 to 60℃.Through the cytotoxicity test, Dpo52 was observed non-cytotoxic to macrophages. Dpo52 inhibited the biofilm formation of S. enteritidis S25 and S32 via its enzymatic activity of extracellular polysaccharide degradation. To our knowledge, this is the first study of a S. enteritidis phage depolymerase. Dpo52 inhibited the biofilm formation of carbapenem-resistant S. enteritidis via its enzymatic activity of extracellular polysaccharide degradation.
Insights
This study identifies a novel phage, vB_Sen_S3P, effective against multidrug-resistant Salmonella enteritidis. Its depolymerase, Dpo52, successfully inhibited biofilm formation in carbapenem-resistant strains.
Area of Science:
- Microbiology
- Bacteriology
- Genomics
Background:
- Salmonella enteritidis causes foodborne illness, with rising multidrug-resistant strains, particularly carbapenem-resistant isolates.
- Bacterial biofilm formation is a key factor contributing to antibiotic resistance.
- Limited research exists on phage depolymerases targeting carbapenem-resistant S. enteritidis.
Purpose of the Study:
- To characterize a novel phage, vB_Sen_S3P, and its depolymerase (Dpo52) for potential therapeutic applications against carbapenem-resistant Salmonella enteritidis.
- To evaluate the efficacy of Dpo52 in inhibiting biofilm formation in multidrug-resistant S. enteritidis strains.
Main Methods:
- Isolation and genomic analysis of the phage vB_Sen_S3P from sewage.
- Expression and purification of the phage depolymerase Dpo52.
- Assessment of Dpo52's host specificity, activity, stability, and non-cytotoxicity.
- Evaluation of Dpo52's impact on S. enteritidis biofilm formation.
Main Results:
- Phage vB_Sen_S3P infected 22 out of 30 clinical S. enteritidis isolates, including carbapenem-resistant strains.
- The depolymerase Dpo52 was successfully expressed, purified, and found to be stable across a wide pH and temperature range.
- Dpo52 demonstrated non-cytotoxicity to macrophages and effectively inhibited biofilm formation in S. enteritidis via extracellular polysaccharide degradation.
Conclusions:
- This is the first report of a Salmonella enteritidis phage depolymerase, Dpo52.
- Dpo52 shows significant potential as a therapeutic agent to combat biofilm formation in carbapenem-resistant Salmonella enteritidis infections.
