Exploring the Biocontrol and PGPR Activity of Soil Bacteria Bacillus cereus CPK6 isolated from the Rhizosphere of Elettaria cardamomum

Abstract

The deleterious effect of chemical fertilizers on the ecological system has coerced to the adoption of sustainable agriculture methods such as implementing biofertilizers and biocontrol agents to enhance plant growth. PGPR (plant Growth-Promoting Rhizobacteria) has been recognized for its ability to directly and indirectly promote plant growth by synthesizing various phytohormones along with biostimulants, exhibiting antagonistic effects against plant pathogens. In our study, we have isolated a total of 15 CPK (Cardamom rhizosphere exposed to pesticide taken from Kanjiyar) bacterial isolates from two different rhizospheric samples of Elettaria cardamomum. The biocontrol and PGPR traits of all the isolates were examined by performing various enzyme assays for chitinase, cellulase, protease, lipase, amylase, nitrogenase and phosphatase, as well as tests for indole acetic acid (IAA), hydrogen cyanide (HCN) and ammonia production. The antipathogenic effect of the isolates against Pseudomonas syringae and Fusarium oxysporum f. sp. cubense was identified using the cross-streak plate method and dual plate assay respectively. Among the 35 isolates, six CPK isolates showed eminent biocontrol activity against both phytopathogens. CPK6 was selected as the potential isolate as it exhibited both PGPR as well as biocontrol activity, along with significant antagonistic traits against both pathogens. The potential bacterial isolate CPK6 was identified as Bacillus cereus CPK6 using 16S rRNA sequencing.