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Improvement of fitness and viable cell qPCR monitoring in a biological control strain of Lactobacillus plantarum

Anna Bonaterra: University of Girona

<div><em>Lactobacillus plantarum</em> PM411 is a biological control agent with broad activity against several quarantine plant pathogenic bacteria. A physiological adaptation strategy was used to increase tolerance of the strain to water stress, consisting of hyperosmotic and acidic conditions during growth. The combined-stress adaptation treatment in PM411 provides a protection not only against water stress, but also a better survival under harsh conditions in the aerial plant surfaces. This beneficial effect is related to a more consistency in bacterial disease suppression and it is expected that the combined methodology could be applied to improve other biocontrol agents and their formulation. To monitor strain PM411, a viability qPCR assay for its detection and quantification in plant materials has been developed. The method uses a nucleic acid-binding dye in combination with the specific qPCR for selectively detecting and enumerating viable bacteria. This method confirmed some limitations of fitness on the plant surface under unfavourable low relative humidity (RH) conditions.</div>