Killing efficiency and full genome sequencing of bacteriophage BAG1 targeting endodontic clinical strain of Enterococcus faecalis

Objectives: Bacterial biofilms can increase the survival of bacteria through providing resistance to conventional disinfectants as well as antibiotics, thus biofilm considered a serious risk to human health with hug loss. Consequently, novel approaches to deal with bacterial biofilms are required. Viruses that may eradicate bacteria are known as bacteriophages, they are also known as “bacteria eaters.” Due to their activity on bacteria, bacteriophages are distinct from other organisms and do not pose a threat to human. Consequently, they are regarded as secure substitutes for antibiotics in the management of bacterial infections. Aim of the Study: In this study, we report the full genome sequencing of bacteriophage, namely BAG1 that targeting an endodontic clinical strain of Enterococcus faecalis (K3). Furthermore, we evaluate it killing efficiency to eliminate E. faecalis in both planktonic media and dentine slabs. Materials and Methods: We used the previously isolated endodontic E. faecalis clinical strain, namely K3 and enterococcus bacteriophage BAG1 in this study by spotting on the double layer agar technique. DNA extracted proceeded with NORGEN phage DNA isolation kit. Phage full genome sequencing was performed using Illumina nova Seq 600, 150 bp PE. In addition, the killing capacity of BAG1 phage against E. faecalis K3 was measured by infecting 5 × 106 E. faecalis with BAG1 phage at multiplicity of infection of 0.1. Furthermore, the biofilm fraction and the number of E. faecalis colony-forming unit in planktonic media were measured after infecting 24 dentine slabs with K3 bacteria and BAG1 phage. SYTO® 9 green LIVE/DEAD® BacLight Bacterial Viability Kits were used to visualize K3 biofilm on dentine slabs using fluorescent microscope. Results: Full Genome Organization of BAG1 phage was circular composed of 68 open reading frame with GC percentage of 34.56%. An efficient killer reflecting by completely eliminating K3 strain within 180 min in killing test. In addition, the result revealed that BAG1 highly significant to eliminate K3 bacteria in both planktonic broth and biofilm fraction obtained from dentine slabs infection with the endodontic K3 clinical strain. Conclusion: Our results support that anti E. faecalis bacteriophage BAG1 significantly eliminate biofilm of E. faecalis K3 on dentine slabs with a lytic properties due to the absence of lysogenic genes which make it a suitable substitute to adjunctive anti E. faecalis therapy.