The microbial terroir of the Greek olive varieties

The microbial terroir of Greek olive varieties remains underexplored. In this study, 62 samples of olive fruits, collected across the harvest period 2019-2020, were analyzed by high-throughput sequencing. The samples represented 38 olive varieties collected from geographically well distributed regions of Greece. Analysis of the bacterial composition revealed that the geographical area was a significant factor in discriminating samples. The core microbiota included Erwinia, Pseudomonas, and members of the Enterobacteriaceae family. Furthermore, a notable variation in bacterial taxa abundances associated with the geographic location was observed. The sampling area was a key discriminant factor for the mycobiota, and the core mycobiota comprised Alternaria, Taphrina, Candida, Wickerhamomyces anomalus and Penicillium. Finally, Redundancy Analysis (RDA) revealed a notable association between environmental characteristics and microbial composition. Specifically, tree age was associated with certain bacterial and fungal taxa (Pearson's correlation p-value adj.[FDR] < 0.05).