Characterization and identification of compatible bacterial and fungal isolates as biological control agents | ||||
| Arab Journal of Biotechnology | ||||
| Volume 20, Issue 1, June 2017, Page 1-20 PDF (2.12 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/arjb.2017.428497 | ||||
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| Abstract | ||||
| Forty six bacterial isolates ;including 24 fluorescent pseudomonads and 22 actinomycetes ; along with ten fungal isolates of Trichoderma spp. were isolated from some plant rhizospheres and evaluated for their relative biocontrol potential using dual culture technique against six phytopathogenic fungi which were isolated from diseased plants and identified based on their morphological characters. Some pathogenic fungi were very resistant while others are very sensitive to inhibition by all the tested bacterial and Trichoderma isolates. The efficient isolates were tested to produce the inhibiting agents siderophore and hydrogen cyanide. Four fluorescent pseudomonads isolates (5 Ps; 7 Ps; 12 Ps; 8 Ps) and three Trichoderma isolates exhibited high antagonistic effects; high production of inhibiting agents and high compatibility was detected among the tested four bacterial or Trichoderma isolates. These Trichoderma isolates were identified using standard identification keys as Trichoderma viride; Trichoderma harzianum and Trichoderma hamatum. The mixture of individual or mixed batch cultures of bacterial strains were tested for their relative bio-efficacy against pathogenic fungi in vitro. Results revealed that the mixture batch culture was less efficient aganist the phytopathogenic fungi compared to single culture except with Rhizoctonia solani and F. moniliforme. Production of IAA; cytokinins; chitinase; siderophores and hydrogen cyanide were determined qualitatively to select the most efficient antagonists.The selected bacterial isolates were genotypically characterised using 16S ribosomal DNA (rDNA) sequencing; and random amplified polymorphic DNA (RAPD) validating as Pseudomonas alcaligenes ; Pseudomonas sp. Pseudomonas fluorescens and Pseudomonas protegens . | ||||
| Keywords | ||||
| Biocontrol; Pseudomonas; Trichoderma; Biological activity; 16S rRNA gene sequencing; Phylogenetic analysis; RAPD–PCR | ||||
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