Long-term starvation-survival of Erwinia amylovora in sterile irrigation water
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Cita bibliográficaBiosca, E. G., Marco-Noales, E., Ordax, M., Lopez, M.M. (2006). Long-term starvation-survival of Erwinia amylovora in sterile irrigation water. Proceedings of the Xth International Workshop on Fire Blight, (704), 107-112.
The role of irrigation water in disseminating Erwinia amylovora is not fully recognized, and the survival of the bacterium in natural water has not been carefully investigated. This risk has been underestimated, since it is generally considered that E. amylovora survives only for a short period in water and its isolation from natural water samples has not been reported. The main goal of this study has been to clarify whether E. amylovora could survive under nutrient starvation conditions usually found in aquatic environments and if it is nonculturable on solid media when recovered from sterile natural water. Infectivity of E. amylovora cells in water was evaluated by using immature pear fruits. Total and viable cell counts were monitored by the Live/Dead viability kit, and culturability by plate counts on King's B medium. E. amylovora was able to survive in water from different sources showing a long persistence in irrigation water and maintaining its infectivity for green pears. However, a progressive loss of culturability on solid media by 2 to 3 logarithmic units during storage time was observed, the rate at which cells became nonculturable dependent on the type of water used. A significant difference in the time to nonculturability between cells maintained in irrigation water and those kept in deionized water was observed, associated with the content of dissolved compounds, which differ for these two types of water. Since bacterial cells maintained their viability, it seems that the oligotrophic conditions found in natural aquatic environments could allow the survival of the fireblight pathogen. Further, the maintenance of the pathogenicity of E. amylovora supports the possible role of water as a reservoir and vehicle for transmission of this pathogen.