Isolation of bacterial and fungal members of the oak microbiota using non-supplemented and supplemented diluted and undiluted growth medium. (A) Number of bacterial isolates obtained from the oak root/rhizosphere, stem, and leaf microbiota, (B) number of fungal isolates obtained from the oak root/rhizosphere, stem, and leaf microbiota. The nutrients of the growth media TSA and MEA were diluted 10-fold while keeping a full-strength agar concentration of 2% for complete solidification. Diluted and undiluted agar media were supplemented with a final concentration of 2% of oak leaf extract. P-values were obtained by comparing the number of bacterial and fungal isolates in a nonparametric Kruskal–Wallis test.