Many studies have explored the potential use of rhizosphereassociated
microbes for biocontrol of soil-borne diseases (Ardakani
et al. 2010; Lahlali and Hijri 2010). Bacillus spp., particularly Bacillus
subtilis and its closely related species, have been widely studied
because of their disease control properties (Ongena et al. 2007;
Huang et al. 2012). Factors contributing to their disease-control
properties include their ability to produce various antimicrobial
compounds (Stein 2005),their efficient colonization ofthe root surface
for long periods of time (Fan et al. 2011), and their long-term
viability, which makes it feasible to develop commercial products
(Lalloo et al. 2010). At present, several B. subtilis strains are commercially
available as biocontrol agents (Harman et al. 2010).
There have been many studies on the antifungal metabolites
synthesized by B. subtilis and their potential applications
in suppressing diseases. B. subtilis can produce more than two
dozen antibiotics, among which the dominant class is lipopeptide
antibiotics. Most of these lipopeptides have a molecular weight
of less than 2000 Da and are synthesized non-ribosomally via a multi-enzyme biosynthesis pathway