Bacteriophages are effective biocontrol strategy as well as ecofriendly remedy for the emerging antibiotic and chemical resistance in bacterial phytopathogens such as bacterial wilt-causing Ralstonia solanacearum. One of the major challenges in the use of bacteriophage therapy for agricultural phytopathogens is maintaining their viability even during variations in pH, temperature, ultraviolet irradiation, and desiccation during field application for sustainable agriculture. In this study, the isolation and characterization of phage ɸsp1 for its efficacy against wilt-causing R. solanacearum performed on Solanum lycopersicum (tomato) seedlings and Solanum tuberosum (potato) tuber assay are reported. Bacteriophage was found to be viable and stable at a wide pH range (3.0–9.0) and at temperatures up to 55 °C. Phage ɸsp1 required ~15 min for adsorption and completed its life cycle in 25–30 min by host cell lysis with a burst size of ~250–300. Phage ɸsp1 eradicated 94.73% preformed R. solanacearum biofilm and inhibited biofilm formation by 73.68% as determined by the static crystal violet microtiter biofilm assay. Transmission electron microscope revealed the phage ɸsp1 to be approximately 208±15 nm in size, comprising of icosahedral head (100 ±15 nm) and tail, as belonging to Myoviridae family. Plant bioassays showed 81.39 and 87.75% reduction in pathogen count using phages ɸsp1 in potato tuber and tomato seedlings, respectively. Reversal in disease symptoms was 100% in phage-treated tuber and tomato plant (pot assay) compared to only pathogen-treated controls. Isolated bacteriophage ɸsp1 was found to be highly host specific, effective in biofilm prevention, and capable of inhibiting bacterial wilt at low multiplicity of infection (1.0 MOI) in tomato as well as potato tuber bioassays. Phages ɸsp1 were environmentally stable as they survive at variable pH and temperature. Bacteriophage ɸsp1 shows a promise for development into a biocontrol formulation for the prevention of R. solanacearum bacterial wilt disease.

中文翻译：

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噬菌体ɸsp1对茄科作物中引起细菌枯萎的青枯雷尔氏菌的生防潜力

噬菌体是有效的生物防治策略，也是对细菌性植物病原体（例如引起青枯病的青枯雷尔氏菌）的新出现的抗生素和化学抗性的环保补救措施。将噬菌体疗法用于农业植物病原体的主要挑战之一是，即使在可持续农业的田间应用中，即使在pH值，温度，紫外线辐射和干燥过程中也要保持其生存能力。在这项研究中，报告了噬菌体ɸsp1的分离和鉴定，该噬菌体ɸsp1具有抗番茄枯萎病的功效，该噬菌体在番茄（Solaum lycopersicum（tomato））马铃薯和马铃薯（potato tubeubeum（potato））块茎试验中进行了鉴定。发现噬菌体在很宽的pH范围（3.0–9.0）和高达55°C的温度下均是可行且稳定的。噬菌体ɸsp1需要约15分钟的吸附时间，并通过宿主细胞裂解在25–30分钟内完成其生命周期，爆发大小约为250–300。噬菌体ɸsp1根除了94.73％的预先形成的茄形青枯菌生物膜，并通过静态结晶紫微滴度生物膜测定法确定，抑制了73.68％的生物膜形成。透射电子显微镜显示噬菌体ɸsp1的大小约为208±15 nm，由二十面体头部（100±15 nm）和尾部组成，属于肌病毒科。植物生物测定法显示，使用噬菌体ɸsp1在马铃薯块茎和番茄幼苗中的病原体数量分别减少81.39和87.75％。与仅用病原体处理的对照相比，在噬菌体处理的块茎和番茄植株（盆栽试验）中，疾病症状的逆转率为100％。发现分离的噬菌体ɸsp1具有高度宿主特异性，在防止生物被膜方面有效，并且能够在番茄以及马铃薯块茎生物测定中以​​低感染复数（1.0 MOI）抑制细菌枯萎。噬菌体ɸsp1在环境中稳定，因为它们可以在不同的pH和温度下生存。噬菌体ɸsp1有望发展成为预防茄枯萎病细菌枯萎病的生物防治制剂。