*4.1. Soil Sampling and Isolation*

For isolation of *Actinomycetes*, 200 g subsamples were collected from the rhizosphere zone of four different plant species: rosemary (3 samples), acacia (3 samples), strawberry (2 samples), and olive (2 samples) from Potenza (Basilicata region, southern Italy). Each soil sample was air-dried on the benches for one week and sieved through a 250 μm pore sieve (Glenammer, Scotland, UK). The samples were further held in a hot-air oven at 121 ◦C for 1 h to prevent the growth of other microorganisms. The isolation was carried out following the membrane filter technique using DifcoTM *Actinomycetes* Isolation Agar (Sparks, MD, USA) [45] with some minor modifications. The cultivated plates were incubated for 4 days at 28 ◦C until the *Actinomycetes* become visible. The prepared nutrient media was supplemented with 100 μg/mL cycloheximide to suppress eventual growth of fungi. All obtained isolates were cultured in triplicates and further purified for obtaining the pure cultures, which were conserved on slant agar nutrient glycerol (ANG) tubes at 4 ◦C for further biological assays. The obtained isolates were initially examined based on their microscopic morphological features with a light microscope. For exact identification, the obtained isolates were further analyzed by the molecular method.
