Developing a bacteriophage cocktail for biocontrol of potato bacterial wilt

Abstract

Bacterial wilt is a devastating disease of potato and can cause an 80% production loss. To control wilt using bacteriophage therapy, we isolated and characterized twelve lytic bacteriophages from different water sources in Kenya and China. Based on the lytic curves of the phages with the pathogen Ralstonia solanacearum, one optimal bacteriophage cocktail, P1, containing six phage isolations was formulated and used for studying wilt prevention and treatment efficiency in potato plants growing in pots. The preliminary tests showed that the phage cocktail was very effective in preventing potato bacterial wilt by injection of the phages into the plants or decontamination of sterilized soil spiked with R. solanacearum. Eighty percent of potato plants could be protected from the bacterial wilt (caused by R. solanacearum reference strain GIM1.74 and field isolates), and the P1 cocktail could kill 98% of live bacteria spiked in the sterilized soil at one week after spraying. However, the treatment efficiencies of P1 depended on the timing of application of the phages, the susceptibility of the plants to the bacterial wilt, as well as the virulence of the bacteria infected, suggesting that it is important to apply the phage therapy as soon as possible once there are early signs of the bacterial wilt. These results provide the basis for the development of bacteriophagebased biocontrol of potato bacterial wilt as an alternative to the use of antibiotics.

Application of Adaptive Evolution to Improve the Stability of Bacteriophages during Storage

“…The phages P-PSG-11 and Wc4 used in this study have previously been shown to be potential biocontrol agents of the potato phytobacteria R. solanacearum [31] and P. carotovorum subsp. carotovorum [32], respectively.…”

“…carotovorum (Pcc) and Pectobacterium atrosepticum (Pba) cause blackleg in the growing plant and soft rot in the potato tuber during storage and transportation [30]. Phages have been considered in the biocontrol of these phytopathogens [31,32]. A major challenge in phage-mediated biocontrol of phytopathogens is phage inactivation by UV light, desiccation, and excess heat.…”

Biocontrol of phytobacteria with bacteriophage cocktails

“…Another method of preparing a phage cocktail would be selecting phages from an assemblage of phages based on phage lytic or lysis curves . A phage lytic curve is a measure of the bactericidal activity of lytic phages.…”

“…In field‐grown plants, phage cocktail application caused a decline in disease severity of ∼ 17%. Several other studies have demonstrated the feasibility of applying phage cocktails as biocontrol agents of phytopathogens . At the same time, they also showed that it is extremely important to have a good phage cocktail and the control efficacy of phage cocktails could be affected greatly by various factors.…”

A Hundred Years of Bacteriophages: Can Phages Replace Antibiotics in Agriculture and Aquaculture?

“…It is worth mentioning that treatment with phage Wc5r proved effective against phage-resistant strains of P. carotovorum [77]; while phage ΦAS1 is an efficient therapy for potato common scab, produced by S. scabies, when used to treat seed tubers [70]. The study by Wei and colleagues, using a phage cocktail to combat the potato bacterial wilt caused by R. solanacearum, resulted in 80% of the plants protected against the bacterial pathogen [74].…”