Phage cocktail containing Podoviridae and Myoviridae bacteriophages inhibits the growth of Pectobacterium spp. under in vitro and in vivo conditions

Abstract

Globally, there is a high economic burden caused by pre-and post-harvest losses in vegetables, fruits and ornamentals due to soft rot diseases. At present, the control methods for these diseases are limited, but there is some promise in developing biological control products for use in Integrated Pest Management. This study sought to formulate a phage cocktail which would be effective against soft rot Pectobacteriaceae species affecting potato (Solanum tuberosum L.), with potential methods of application in agricultural systems, including vacuum-infiltration and soil drench, also tested. Six bacteriophages were isolated and characterized using transmission electron microscopy, and tested against a range of Pectobacterium species that cause soft rot/blackleg of potato. Isolated bacteriophages of the family Podoviridae and Myoviridae were able to control isolates of the Pectobacterium species: Pectobacterium atrosepticum and Pectobacterium carotovorum subsp. carotovorum. Genomic analysis of three Podoviridae phages did not indicate host genes transcripts or proteins encoding toxin or antibiotic resistance genes. These bacteriophages were formulated as a phage cocktail and further experiments showed high activity in vitro and in vivo to suppress Pectobacterium growth, potentially indicating their efficacy in formulation as a microbial pest control agent to use in planta.

Pectobacterium brasiliense: Genomics, Host Range and Disease Management

“…There has been, however, an extensive amount of research on biocontrol of the most widespread economically important SRP, especially Dickeya solani , P. carotovorum and P. atrosepticum [ 5 , 134 , 135 , 136 , 137 , 138 , 139 , 140 ]. In fact, biocontrol of SRP using bacteriophages has progressed the most among other methods, with a stage where formulated commercial product is available, including Biolyse ® , which was demonstrated to be efficacious at preventing soft rot in packaged potatoes caused by Pectobacterium and Dickeya species [ 141 ].…”

“…Carstens et al [ 136 ] reported significant suppression of soft rot caused by P. atrosepticum using a phage cocktail containing six selected bacteriophages on potato tubers in simulated storage conditions. The phage efficacy to control Pbr in field trials has not been reported so far [ 19 ], however, recently the efficacy of single bacteriophages or phage cocktails to control P. carotovorum and P. atrosepticum was proven under field conditions [ 14 , 138 , 139 ].…”

Population Dynamics between Erwinia amylovora, Pantoea agglomerans and Bacteriophages: Exploiting Synergy and Competition to Improve Phage Cocktail Efficacy

“…Studies of in vitro phage-host interactions in liquid culture commonly use optical density to compare bacterial growth dynamics in response to different phage treatments [18][19][20][21][22][23]. Optical density measurements are quick and amenable to high-throughput comparison using 96-well incubating spectrophotometers, and hosts can even be fluorescently labeled to allow differentiation [24].…”

Use of a Specific Phage Cocktail for Soft Rot Control on Ware Potatoes: A Case Study

“…Moreover, postharvest application of Pectobacterium phages is allowed in Europe [4]. Numerous attempts have been made to systematize the application of individual phages and phage cocktails to protect potatoes from soft rot [4][5][6][7][8][9][10][11]. However, most studies were limited to in vitro conditions and model strains of the pathogens.…”