Isolation and Identification of Klebsiella aerogenes RS 1 for Biocontrol of Sclerotium rolfsii and Its Growth‐Promoting Potential

Abstract

Plant growth‐promoting rhizobacteria (PGPR) represent a sustainable approach to enhance agricultural productivity. In this study, strain RS1, exhibiting potent biocontrol traits, was isolated from tobacco rhizosphere soil. Phylogenetic analysis based on concatenated 16S rRNA and rpoB gene sequences, combined with average nucleotide identity (ANI) values ranging from 95.7% to 100%, identified RS1 as Klebsiella aerogenes . Whole‐genome sequencing revealed a 4.46 Mb genome containing genes associated with multiple indole‐3‐acetic acid (IAA) biosynthetic pathways, including ipdc , iaaH and a complete ddc‐mao‐aldh gene cluster associated with the TAM pathway. The genome also harboured genes associated with siderophore production ( entA , entB , entC and entE ), phosphate solubilization ( gcd and the pqq operon) and organic phosphorus mineralization ( phoA and phn ). Phenotypic assays indicated indole‐3‐acetic acid (IAA) production, siderophore production, inorganic phosphate solubilization and organic phosphorus mineralization. RS1 significantly enhanced tobacco biomass, increasing fresh weight by 64.4% and dry weight by 72.9%, and significantly increased the activities of key antioxidant enzymes, including catalase (65.0%), peroxidase (147.3%) and superoxide dismutase (31.8%). Furthermore, RS1 exhibited broad‐spectrum antagonism against eight phytopathogens, with inhibition rates ranging from 53.2% to 86.1%, and suppressed Sclerotium rolfsii lesion development on detached tobacco leaves, demonstrating its dual potential as a plant growth‐promoting and biocontrol strain. These multifunctional attributes highlight RS1 as a promising microbial inoculant for sustainable agriculture.