Antagonistic and plant growth promoting potentials of bacteria isolated from different organic manures

In search of efficient PGPR strains with multiple activities, a total of 68 bacterial isolates obtained from five organic manures viz., panchgavya, vermicompost, vermiwash, matka khad and farmyard manure were characterized biochemically and screened in vitro for their antagonistic properties against fungal phytopathogens namely Sclerotium rolfsii, Fusarium solani f.sp. pisi, F. oxysporum f.sp. pisi, Sclerotinia sclerotiorum, Rhizoctonia solani, Colletotrichum capsici and Phytophthora nicotianae var nicotianae as well as their growth promoting traits such as phosphate solubilization, indole acetic acid (IAA) and siderophore production. Out of sixty eight, twelve isolates possessed strong antagonistic activities. All the species of Bacillus were highly effective against fungal pathogens with more than 95% mycelial inhibition followed by Serratia (96% inhibition) and Actinomycetes (94% inhibition). Maximum phosphate was solubilized by isolates of Serratia (AP18) (366.07μg/ml). Among all, Pseudomonas isolates were able to produce highest levels of IAA (52.59 μg/ml). Bacillus isolates (AV5, AP13 and AP21), Serratia (AP18) and Actinomycetes (AC20) presented high activity of siderophore. Thus, these promising bacterial isolates obtained from the present study may be commercially formulated as effective biocontrol agents for the management of fungal pathogens of plants.