Biological control, the use of specific microorganisms
that interfere with plant pathogens and pests, is
a nature-friendly, ecological approach to overcome
the problems caused by standard chemical methods
of plant protection. Commercial preparations for plant
disease biocontrol are all based on the practical application
of a few species of rhizosphere-competent
bacteria and more than 10 species of fungi (Chernin
& Chet 2001). The general mechanism of biological
control can be divided into direct and indirect effects
of the biocontrol agent (BCA) on the plant pathogen.
Direct effects include competition for nutrients
or space, production of antibiotic and lytic enzymes,
inactivation of the pathogen’s enzymes and parasitism.
Indirect effects include all those aspects that
produce morphological and biochemical changes in
the host plant, such as tolerance to stress through enhanced
root and plant development, solubilization or
sequestration of inorganic nutrients, and induced res