Trichoderma species inhibited the growth of the target microorganism
through its ability to grow much faster than the pathogenic
fungus thus competing efficiently for space and nutrients and
forming coiled structures around the hyphae of F. solani. Starvation
has been regarded as the most common cause of death for microorganisms,
so that competition for limiting nutrients resulted in biological
control of fungal phytopathogens (Mokhtar and Aid, 2013).
Moreover, coiling is characteristic of the interaction between
mycoparasitic and phytopathogenic fungi, leading to penetration
of the cell wall of pathogen followed by the breakdown of chitin
by production of chitinase and glucanase enzymes at the site of
endophyte penetration (Zeininger et al., 1999; Antal et al., 2000).
Then, the released antibiotics permeate the affected hyphae and
inhibit resynthesis of the phytopathogenic cell wall (Tijerino
et al., 2011). The observed variation in fungicidal activity among
the two Trichoderma isolates could be the signature of different
types of chemical constituents secreted in the isolates