ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF INDIGENOUS BIOCONTROL AGENTS

Abstract

A study was performed to isolate, identify and characterize the potential indigenous bio control agents and test them against pathogenic fungi from the rhizosphere soil of crop from different location (viz. Dhaka, Gazipur, Manikganj, Noakhali, Joypurhat and Rajshahi) and mushroom substrate (Savar). The experiment was conducted in the MS Laboratory of Department of the Plant Pathology, Faculty of Agriculture, Sher-e-Bangla Agricultural University during July 2021 to June 2022. Nineteen different indigenous bacterial strains (Rhizobium sp., Mesorhizobium sp., Azospirillum sp., Azotobacter sp., Agrobacterium sp., Streptomyces sp., Burkholderia sp., Xanthomonas sp., Acidovorax sp., Pectobacterium sp. Erwinia sp., Ralstonia sp., Salinico roseus, Pseudomonas aeruginosa, Bacillus sp., Bacillus cereus Lactobacillus sp., Thermomonospora sp. and E. coli) and fifteen indegenous fungal species (Sclerotium sp., Rhizoctonia sp., Cunninghamela sp., Chaetomium sp., Alternaria sp., Curvularia sp., Penicillium sp., Trichoderma harzianum, T. viride, T. hamatum, Aspergillus niger, A. flavus, A. terreus, Fusarium oxysporum and Fusarium sp.) were isolated by dilution plate method using 10 and 10 4 dilution in case of bacteria and fungi, respectively. Bacteria were identified and characterized by their cultural characteristics; observing 10 biochemical tests response and selective media growth. In case of fungal species morphological and microscopical observation were done. The bio-efficacy of the identified indigenous bacteria and fungi were tested and among the isolated fungi 3 fungal genera were selected as soil borne pathogenic fungi (Sclerotium, Rhizoctonia and Fusarium oxysporum) for trial in dual culture technique. Only Trichoderma harzianum, T. viride, T. hamatum, Bacillus cereus and Pseudomonas aeruginosa were found effective against the pathogenic fungi in dual culture technique. In case of fungi the inhibition of Sclerotium sp. was 86.48% by T. harzianum, 89.18% by T. viride and 48.64 % by T. hamatum; inhibition of Rhizoctonia sp. was 50% by T. harzianum, 62.5% by T. viride and 80% by T. hamatum; and the inhibition of Fusarium oxysporum was 68.42% by T. harzianum, 70.52% by T. viride and 81.5%. by T. hamatum. In case of bacteria the inhibition of Sclerotium sp. by Bacillus cereus was 72.98% and by Pseudomonas aeruginosa was 62.16%.; inhibition of Rhizoctona sp. by Bacillus cereus was 70% and by P. aeruginosa was 50%; inhibition of Fusarium oxysporum by Bacillus cereus was 66.67% and by P. aeuginosa was 60%. This study filters the potential indigenous biocontrol agents those can be used as bio-pesticide to develop crop production and reduce the chemical dependency.