Isolation and Identification of Rhizosphere Soil Chitinolytic Bacteria and their Potential in Antifungal Biocontrol

Four hundred bacterial isolates were isolated from rhizosphere of some plants collected from Egypt and screened for production of chitinase enzyme. Only four isolates designated MS1, MS2, MS3 and MS4 were the most potent chitinolytic bacterial species. SDS-PAGE analysis of vegetative and sporulated cells of the four isolates revealed that the protein profile of the four isolates were different from each other in their banding pattern and were identified as Bacillus licheniformis, Stenotrophomonas maltophilia, Bacillus licheniformis and B. thuringiensis. In vitro MS1 and MS3 were the most active species, so they suppressed the growth of all tested pathogenic fungi (Rhizoctonia solani, Macrophomina phasiolina, Fusarium culmorum, Pythium sp, Alternaria alternata and Sclerotium rolfsii). Also, MS3 produced the highest level of chitinase enzyme (1.27 μ/ml) after 4 days incubation as compared with the other isolates. In green-house experiment, B. licheniformis (MS3) significantly reduced the damping off disease caused by Rhizoctonia solani, in Helianthus annus using the seed coat or soil draing treatments.