Abstract: Plant bacterial wilt caused by Ralstonia solanacearum is a serious vascular soil-borne disease. Occurrence and severity of the disease is positively related to the population of bacteria in the soil, therefore rapid and accurate detection of the bacteria population in the soil is the premise of the disease forecasting and effective control. In this study, the biological characteristics of a potential biocontrol Ralstonia phage P3 strain were tested, and the feasibility detecting of R. solanacearum in soil by the phage strain was also determined. The results showed that phage P3 strain had an icosahedron head and a very short tail under the transmission electron microscopy (TEM). The host range of phage P3 strain was wide, and it could infect the R. solanacearum isolated from tobacco, tomato, pepper, potato and sweet potato. Its multiplicity of infection was 0.0001, incubation period was about 60 min, lysis period was about 80 min, and burst size was about 179. Phage P3 strain was not sensitive to chloroform, and it could maintain high activity in the surroundings at less than 55℃ and pH 4-12. It was sensitive to ultraviolet ray and lost activity under UV vertical irradiation for 18 min. The titers of phage P3 strain was stable in one month under the environment of 20℃-28℃. Under the same conditions, the sensitivity of detecting the population of R. solanacearum in soil by phage was 10 times of the method by the plate culture, the population was 2.83×10⁵ CFU/g in soil by the phage test, but the population was only 1.79×10⁴ CFU/g by the plate culture. In this study, the population of R. solanacearum in tobacco rhizosphere was detected by the phage method, which could provide a technical support for the forecasting of tobacco bacterial wilt disease in the future.

Key words: Ralstonia solanacearum, lytic phage, biological characteristics, detection