Biocontrol of Root Infecting Plant Pathogenic Fungus, Sclerotium rolfsii using Mycolytic Enzymes and Chitin Metabolism Inhibitors Singly and in Combination

A combined effect of mycolytic enzyme mixture and the cell wall chitin metabolism inhibitors to control the growth of a ischolar_main infecting fungus, Sclerotium rolfsii on peanut was studied. Around 10 microbial cultures were screened for their potential to produce extracellularly cell wall synthesis inhibitors, using hyphal tip bursting test with different fungi. Most of them exhibited significant in vitro inhibition of enzymes viz., chitin synthase, endo-chitinase or N-acetylglucosaminidase activities. In a pot experiment, irrigation with crude culture filtrate of Bacillus sp. 102 (1 mg·50ml^-1) which showed hyphal tip bursting in all the test fungi inhibited 70 percent growth of S. rolfsii. Daily irrigation with the mycolytic enzyme preparation of Myrothecium verrucaria diluted to give chitinase activity (0.04 U. 50 ml^-1) inhibited 40 per cent growth of S. rolfsii. The mixture of two viz. M. verrucaria and Bacillus sp. 102 culture filtrates, controlled 80 per cent S. rolfsii infection of peanut seeds. Further fractionation of the inhibitor mixture was also carried out using (60-120 mesh) silica gel column chromatography and preparative TLC. The results with respect to the hyphal tip bursting and enzyme inhibition have been discussed.