For a long time the plant protective activity of PGPR has been
correlated with the potential to secrete a wide array of antibiotic
compounds upon growth as planktonic cells in isolated cultures
under laboratory conditions (Velivelli et al., 2014). A recent
comparative study performed with six strains belonging to the
B. subtilis/amyloliquefaciens species complex corroborated our
earlier finding that antifungal activity is linked with the ability
to produce cyclic LP. Remarkably, production of iturin and
fengycin in B. amyloliquefaciens was enhanced in presence of
certain phytopathogens (Cawoy et al., 2015). This is in line with
a recent finding that non-ribosomal synthesis of antifungal and
antibacterial compounds including bacillibactin is stimulated in
presence of plant pathogens under laboratory conditions