Identification And Biological Characteristics Of Bacteriophages That Lyze Proteus Vulgaris

P. vulgaris which has a wider distribution in nature is a normal human intestinal flora. Only on the occasion which it leaves the normal alien intestine and enters into other parts of human body, P. vulgaris can cause infection. In the hospital, decreased body resistance of patients who receive treatment with long-term broad-spectrum antibiotics, hormones, immunosuppressive agents and antineoplastic agents are easily affected. To some extent, advanced examination and treatment methods provide a way for P. vulgaris to invade the human body, which makes P. vulgaris an important role in hospital infections.At present, aiming at disadvantage with easily producing residues and antibiotic resistance when traditional antibiotics treat animal bacterial infection, bacteriophage therapy have shown many outstanding advantages. After a large number of animal models tests and human clinical practice, people began to focus on shortcomings and deficiencies in the treatment. From the choice of therapeutic phage, host spectrum, the role of force and the dynamics of its role, people use molecular biology techniques for the tentative transformation of phage to obtain more effective treatment, maintain the health of human and animal.In this study,double-agar methods were employed to indentify plugues that containing phages lysing P.valgris of phage DNA were carried out according to Molecular Cloning Manual, and extracted DNA were digested with restriction enzymes .MOI and growth curve of phage were detected.The study used 10 clinical isolates of P. vulgaris mirabilis as host bacterium to isolate 4 virulent bacteriophages from the resident sewage which were named phage Pr-v 01, phage Pr-v 02, phage Pr-v 03 and phage Pr-v 04.The plaque of phases is circular, transparent and clear boundary. Pr-v 04. phage has the highest titer which is 2.06×1012PFU/ml and form a lysozyme plaque of 0.8 ~ 2.3mm in diameter. Cross experiments showed that phage Pr-v 04 had strong lysis ability, high titer, wider cracking spectrum, so it was screened as the object of study. Electron microscopy showed that phage Pr-v 04 had a shape of tadpole, a head of three-dimensional symmetric polyhedron, a diameter of about 40～50nm and a short tail. Genomic DNA by EcoRⅠ, HindⅢand NedⅠdigested confirmed to double-stranded DNA, its genome size is about 26kb, and a number of EcoRⅠrestriction sites. Phage infection of the host Pr-v 04 one- step growth curve suggested that an incubation period is 15min, outbreak time is about 18min and burstsize is 170 or so. The best MOI of Phage Pr-v 04 which infected its host is 0.1. At 4℃, the plaque can be stored for 10 months or so. The injectable suspension of phage Pr-v 04 and its host bacteria can be stored at least 6 months.