The current study was aimed to screen of certain rhizospheric bacterial biocontrol agents against some pathogenic fungi. The obtained data revealed that among 116 bacterial isolates, nineteen bacterial isolates showed the highest inhibition percentage against Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii. Regarding the antifungal activities, results indicated that isolates B38 and B103 recorded the higher values of chitinase activity, catecholate-type siderophores and NH3. Also data showed that isolate B103 was the highest producer for HCN followed by the isolates number B13 and B38. Concerning the production of volatile compounds, data indicated that isolates B103 and B38 showed considerable inhibition against pathogenic fungal growth. Data also showed that poly medium was the best medium for production of inhibitive substances for pathogenic fungi by the tested bacteria. Moreover, cultural filtrates of bacterial biocontrol agents with concentration of 10% showed the highest reduction percentage of mycelial weight of the tested strains after 3 days. The most potent isolates for bioagent production were chosen and these isolates were identified as Pseudomonas fluorescens (B103) and Bacillus subtilis (B38). Keywords: biocontrol agents, F. oxysporum, R. solani, S. rolfsii, chitinase, siderophores, NH3, HCN, volatile antibiotics, Pseudomonas fluorescens, Bacillus subtilis. |
