TITLE:
Evaluation of Bacteriophages for the Biocontrol of Tomato wilt Disease Caused by Ralstonia solanacearum
AUTHORS:
Phyvian Wafula, Ruth Amata, Juliah Akhwale
KEYWORDS:
Ralstonia solanacearum, Bacteriophages, Bacterial Wilt, Bio-Control, Tomatoes
JOURNAL NAME:
Advances in Molecular Imaging,
Vol.14 No.1,
January
30,
2025
ABSTRACT: Aim: This study was carried out in order to evaluate the potential of bacteriophages in controlling tomato bacterial wilt disease caused by Ralstonia solanacearum. Study design: A purposive sampling technique was used to collect samples from bacterial wilt hot spot tomato growing areas in Kenya. Place and duration of study: The research work was done at Jomo Kenyatta University of Agriculture and Technology, between June 2020 and July 2021. Methodology: Thirty diseased plants and corresponding soil were collected from five counties, Nyeri, Kajiado, Nyandarua, Kiambu and Taita Taveta. Bacteria were isolated and characterized, and then used as hosts to propagate the phages. Tests done were gram stain, oxidation test, potassium hydroxide solubility test, H2S production test catalase test, NaCl test and sugar fermentation test. Molecular analysis and phenotyping were also done in order to identify the bacteria. The bacteriophages were then isolated through a double overlay method using R. solanacearum as the host. They were characterized and assayed in a greenhouse setting to determine their effectiveness in controlling bacterial wilt. Results: Six host bacteria were isolated and all belonged to biovar II. Four phages were observed based on morphology. Upon characterization the phages were stable at 30˚C, PH range between 6 - 7 and tolerance of more than an hour under UV light. In the greenhouse experiment, treatment of plants with bacteriophage prevented wilting after subsequent inoculation with the pathogen. A bacteriophage mix of SN1 and WT1 were used for efficacy tests due to their efficiency in plating and infection. Phage SN1 and WT1 exhibited high lytic activity and relatively high thermotolerance and acid tolerance, thereby showing great potential in the biocontrol of bacterial wilt infection across a variety of conditions. Conclusion: The results obtained in this research show that bacteriophages offer potential for the biocontrol of bacterial wilt.