<p class=\"MsoNormalCxSpFirst\" style=\"margin-bottom: .0001pt; mso-add-space: auto; text-align: justify; text-justify: inter-ideograph; line-height: 150%;\"><strong><span style=\"font-size: 12.0pt; line-height: 150%; font-family: \'Times New Roman\',\'serif\'; mso-fareast-font-family: \'Times New Roman\'; color: #222222;\">Abstract</span></strong><span style=\"font-size: 12.0pt; line-height: 150%; font-family: \'Times New Roman\',\'serif\'; mso-fareast-font-family: \'Times New Roman\'; color: #222222;\">: Auxotrophic&nbsp;mutants of&nbsp;&nbsp;<em>Trichoderma harzianum&nbsp;</em>were obtained<em>&nbsp;</em>by exposing spores to UV light of 254 nm wavelength. Separation of auxotrophs was done by using minimal medium and filtration of germinated prototrophs. Using replica plate technique colonies from complete medium were transferred to minimal medium and auxotrophs were identified as colonies showing growth on complete medium and failed to grow on minimal medium. Characterization of auxotrophs was done with respect to checking enzyme activities, identification of auxotrophy for particular amino acid, purines and pyrimidines and checking the effect of mutants on germination and growth of plant pathogens&nbsp;<em>Rhizoctonia solanii, Sclerotium rolfsii, Fusarium oxysporum.</em>&nbsp;Aux-2 and Aux-3 mutants were auxotrophic for Methionine and Histidine respectively.&nbsp;&nbsp;Aux-2 deficient in amylase production, showing enhanced production of cellulase and yellow coloured diffusible metabolite than parental strain. Aux-2 can inhibit germination inhibition of&nbsp;<em>Rhizoctonia solanii, Sclerotium rolfsii&nbsp;</em>and<em>&nbsp;Fusarium oxysporum</em>&nbsp;86%, 70% and 75% respectively. Thus auxotrophic mutant can be better bio-control agent than parental strain.</span></p>
<p class=\"MsoNormal\" style=\"margin-bottom: 0.0001pt;\"><strong><span style=\"font-size: 12.0pt; font-family: \'Times New Roman\',\'serif\'; mso-fareast-font-family: \'Times New Roman\'; color: #222222;\">Key words:&nbsp;</span></strong><span style=\"font-size: 12.0pt; font-family: \'Times New Roman\',\'serif\'; mso-fareast-font-family: \'Times New Roman\'; color: #222222;\">Bio-control agent, Germination inhibition, antifungal activity, hyperparasite</span></p>
 
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