Bacteriophage viruses are a promising tool for preventing and treating bacterial infections. In this sense, phage therapy is an eco-sustainable approach that has the potential to be used as either an alternative or a complement to other strategies for the management of Xylella fastidiosa diseases. The main objective of this work was the search, isolation, selection and characterization of bacteriophages against this phytopathogenic bacterium. Due to the fastidious and slow growth of X.

more »

... a on solid culture medium, we selected strains of phylogenetically-related Xanthomonas species as surrogate hosts for phage hunting in a first approach. Plant host, water and soil samples from the X. fastidiosa outbreaks in Balearic Islands and Alicante, as well as wastewater samples from different locations in the province of Valencia, were screened for the presence of phages able to form plaques on bacterial lawns of Xanthomonas spp. strains by using the overlay method. A total of 22 bacteriophages were isolated, all of them from sewage: 14 infecting the strain IVIA 1317-1a of Xanthomonas arboricola pv. juglandis and 8 infecting the strain CECT 914 of X. axonopodis pv. phaseoli. Bacteriophages were isolated, purified, and amplified. Their lytic activity was tested against more than 25 strains of Xanthomonas spp., and the results suggest differences in the host infection range. Ongoing experiments running to evaluate the effect of the 22 isolated bacteriophages against different strains of X. fastidiosa in liquid medium indicate that at least five phages are able to reduce the growth of the strains, in some cases even to total inhibition. All bacteriophages are currently being characterized phenotypically and genomically, and will be compared with previously described phages.