Streptomyces strains as biocontrol agents against fungal soilborne pathogens

Abstract: The Streptomyces genus represents a good source of microorganisms, bioactive
compounds, antibiotics, and extracellular enzymes active against phytopathogens (BCAs) and for promotion of plant growth (PGPAs). A specific strain of Streptomyces albidoflavus, CARA17, used as BCAs by colony and by culture filtrate (containing putative bioactive crude extracts), provided good abilities to contrast soilborne fungi, such as Athelia rolfsii, Fusarium oxysporum, Plectosphaerella ramiseptata, Sclerotinia sclerotiorum and Verticillium dahliae, both in in vitro and in vivo conditions. CARA17 strain, in dual culture, was significantly able to inhibit all fungi used with different degrees except A. rolfsii. Greenhouse experiments further demonstrated that CARA17 strain significantly reduced disease severity and promoted better plant growth in lettuce seedlings artificially inoculated with the above mentioned fungal pathogens.