Isolation and characterization of Klebsiella oxytoca from the rhizosphere of Lotus corniculatus and its biostimulating features

Isolamento e caracterização de Klebsiella oxytoca da rizosfera de Lotus corniculatus e suas características bioestimulantes

Abstract

Significant food resource shortages are occurring worldwide. Plant growth-promoting rhizobacteria (PGPR) represent an ecofriendly and efficient approach for increasing soil fertility and plant productivity. The current study explored biostimulating traits of PGPR from the rhizosphere of Lotus corniculatus growing in the Al-Ahsa region. A bacterial isolate (LCK121) was obtained, characterized for phenotypic, and identified by 16S rRNA gene sequencing. In addition, its growth-stimulating effects on barley were investigated. The strain identity was confirmed via comparative analysis of the 16S rDNA sequences with Klebsiella oxytoca (99.3% similarity level). LCK121 exhibited multiple plant growth-promoting features, including indole-3-acetic acid (IAA) production (16.34 µg mL^-1), 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity (1.35±0.02 µmol α-ketobutyrate mg⁻¹ h⁻¹), phosphate solubilization, and nitrogen fixation. Furthermore, in vitro inoculation of barley with LCK121 significantly increased the root and shoot dry weights. The results highlight the potential of LCK121 for developing green fertilizers for sustainable agriculture.

Keywords:
plant biostimulation; rhizosphere Lotus corniculatus; Hordeum vulgare; Klebsiella