Recombinant T4 coliphage gp37 gene can expand its host range in Salmonella

Abstract:

[Objective] In this study, the host range of phage QL01 was changed by replacing the gene fragment of QL01 gp37. This lays the foundation for studying the host range mechanism of T4 phage and rapid screening of phages targeting specific pathogens. [Methods] Eight gene fragments on WG01 gp37 were substituted by QL01 using homologous recombination, and then the different chimeric phages were screened and their host range determined by using Salmonella as the host strain. Finally, the biological characteristics such as the optimal multiplicity of infection, one-step growth curve, and other biological characteristics of the chimeric phage QWG were analyzed, as well as the genetic stability. [Results] A total of five chimeric phages (QWA, QWC, QWF, QWG, QWFG) were obtained in this experiment. The results of the host range analysis test showed that chimeric phage could lyse 7, 8, 4, 10 and 9 strains of Salmonella, respectively, compared to phage QL01. That is to say, chimeric phages have all obtained a relatively broad host range of which the host bacteria of QWG widened the most. The results of biological characteristics test showed that the chimeric phage QWG has stable biological properties. We cultured the chimeric phage QWG continuously for 20 generations, sequenced the tail genes from the first and 20th generation chimeric phage and analyzed their hereditary stability. The sequencing results indicated that the gene fragment of the chimeric phage engineered part could stably inherit. [Conclusion] Genetic engineering can generate chimeric phage with broadened host range and hereditary stability, which provides a possibility for rapid screening of phage against specific pathogens.