Abstract:
ABSTRACT--- Chitinolytic enzyme producing by Trichoderma spp. have long been recognized as an agent for controlling plant diseases caused by various phytopathogenic fungi. Chitin is the main structural component of fungi. Chitinase is an enzyme responsible to metabolize the chitin. Primary screening of chitinase producing fungi is essential to obtain an efficient and novel biocontrol agent. In this study, A total of 20 species belonging to 4 genera of fungi were isolated from different agricultural fields in Khartoum and River Nile States during November 2014 to May 2015. The mycoflora were isolated by using soil dilution technique and soil plate technique on Potato Dextrose Agar and Czapek's Dox Agar medium supplemented with chitin and streptomycin. The fungal isolates were screened for the production of chitinase enzyme depending on the index of chitinolytic activity. Morphological identification and characterization of the best chitinase producers were carried out with the help of authentic manuals of fungi. Four isolates showed high index of chitinolytic activity and three of them were belong to the genus Aspergillus. (one was Aspergillus fumigatus and two were Aspergillus awamori) and the last isolate was identified as Trichoderma harzianum. The 4 isolates were selected for biocontrol experiments against Fusarium oxysporium. Antagonism of T. harzianum and the three Aspergillus isolates were observed in vitro by using the dual culture techniques. All isolates showed high antagonism against Fusarium solani specially the isolates of Aspergillus awamori SUDA1,SUDA3 and Trichoderma harzianum SUDT which inhibit the growth 100% at day 14 and 12 respectively, while Aspergillus fumigates SUD5 reduced the growth to78.3% at day 14.
