Effects of atmospheric plasma corona discharge on agrobacterium tumefaciens survival

Yulia Lazra, Bharath Gandu, Irina Dubrovin Amar, Efrat Emanuel, Rivka Cahan

פרסום מחקרי: פרסום בכתב עתמאמרביקורת עמיתים

תקציר

Soil‐borne pathogenic microorganisms are known to cause extensive crop losses. Agrobac-terium tumefaciens, a member of the Proteobacteria, causes the neoplastic crown gall disease in plants. Plant protection is mainly based on toxic chemicals that are harmful to the environment. The use of cold atmospheric‐pressure plasma is an attractive method for microbial eradication. Its anti-microbial mechanism includes the formation of large quantities of reactive oxygen species (ROS). The advantages of eradicating bacteria using cold plasma are not needed for chemicals, short treat-ment, and environmental temperatures. This study examined the impact of plasma corona discharge exposure on A. tumefaciens viability, membrane permeability, relative cell size, and ROS for-mation. The results showed that 90 s of plasma exposure led to a reduction by four orders of mag-nitude when the initial concentration was 1 × 107 CFU/mL and in a dry environment. When the initial concentration was 1 × 106 CFU/mL, 45 s of exposure resulted in total bacterial eradication. In a liquid environment, in an initial concentration of 2.02 × 106 CFU/mL, there was no complete bacterial eradication even at the most prolonged examined exposure (90 s). The influence of plasma treatment on the membrane permeability of A. tumefaciens, and their possible recovery, were ana-lyzed using flow cytometer analysis using propidium iodide (PI). When the plasma‐treated bacteria were suspended in Luria–Bertani (LB) (rich medium), the PI‐positive count of the plasma‐treated bacteria after two hours was 12 ± 3.9%. At the 24th hour, this percentage was only 1.74 ± 0.6%, as the control (0.7 ± 0.1%). These results may indicate the repair of the plasma‐treated bacteria that were suspended in LB. At the 24th hour, the relative cell size of the treated bacteria shifted to the right, to ~3 × 104 forward side scatter (FSC), about 0.5‐fold higher than the untreated cells. Measure-ment of the ROS showed that the intracellular fluorescence of the 90‐s plasma‐treated cells led to significant fluorescence formation of 32 relative fluorescence units (RFU)/cell (9 × 104 fold, compared to the nontreated cells). This study showed that cold plasma is a useful method for A. tumefaciens eradication. The eradication mechanism involves ROS generation, membrane permeability, and changes in cell size.

שפה מקוריתאנגלית
מספר המאמר32
כתב עתMicroorganisms
כרך10
מספר גיליון1
מזהי עצם דיגיטלי (DOIs)
סטטוס פרסוםפורסם - ינו׳ 2022

ASJC Scopus subject areas

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