Comparison of methods used in the recovery of Phylloplane bacteria: a case study of Pseudomonas savastanoi pv. savastanoi applied to the Phylloplane of Olea europaea sub-species

An efficient and accurate method of sampling, recovery, and enumeration of epiphytic bacterial populations are of fundamental importance for their precise estimation. In this study, effectiveness and reliability of processing methods, sampling type, sample storage, and plating techniques, for the recovery of the epiphytic bacterial populations, were evaluated. Pseudomonas savastanoi pv. savastanoi, the causal agent of olive knot disease, and two olive sub-species were used. Bulk-leaf sampling allowed for a higher number of the bacterial recovery. The use of a lab blender was the most effective and reliable method among the four commonly used processing methods. A short storage of leaf samples was possible through freezing. Bacterial survival was not influenced as long as the samples were processed within 5 days and frozen without a buffer. No difference was observed among the drop and spread platings, suggesting that one of them can be used and the choice depends on the cost and time required.