Effect of chitin adapted and ultra violet induced mutant of Trichoderma harzianum enhancing biocontrol and chitinase activity.

A wild strain Trichoderma harzianum was grown on 0.5 to 5 % colloidal chitin medium for adaptation to obtain chitinase rich mutants and the same wild strain was mutated by UV irradiation. Mutants were screened on 1 % colloidal chitin medium and selected based on their ability to produce lysis zones around the colonies. Biocontrol efficacy of the mutants and wild strain were tested against phytopathogens such as Fusarium oxsporum, Bipolaris oryzae, Rhizoctonia solani and Alternaria sp. by dual culture assay on PDA medium. The overall inhibition of phytopathogens by wild, adapted and UV mutant were 69.9 %, 75.5 % and 82.7 %, respectively. The maximum chitinase and protein content were recorded on day 6, in 1 % colloidal chitin amended medium with Czapek- Dox broth pH 6.5 at 28±2 °C. Total chitinase 1.3, 1.6, specific chitinase 1.7, 2.2 and protein 1.3, 1.8 fold were increased by adapted, UV mutant respectively on the 6 days of incubation. The UV mutant strain H11 showed more extra cellular chitinase and protein production, when compared to the adapted mutant and wild strain. SDS-PAGE analysis showed, UV mutant had 20 major protein bands with up regulation was observed than adapted mutant (15 bands) and wild strains (11 bands). T. harzianum mutant H11 showed maximum inhibition of the above pathogens and chitinase activity with protein content confirming the superior efficacy of the mutant and it could be exploit for industrial and agricultural purposes.