Chitosan and Gold Nanoparticles Supplementation for Augmentation of Indole-3-Acetic Acid Production by Rhizospheric Pseudomonas aeruginosa and Plant Growth Enhancement

The present study has been focused to evaluate the effect of chitosan nanoparticles (CNPs) and gold nanoparticles (AuNPs) on the phytohormone production by rhizospheric Pseudomonas aeruginosa. The gold nanoparticles were synthesized biologically and characterized by UV–Visible spectrophotometry, transmission electron microscopy, and X-ray diffraction analysis. The indole-3-acetic acid (IAA) production by P. aeruginosa supplemented with CNPs and AuNPs was quantified by using Salkowski’s method and confirmed by high-performance liquid chromatography (HPLC) analysis. This revealed the effect of 5 mg/mL CNPs and 100 µg/mL AuNPs to enhance the IAA production by P. aeruginosa. By Salkowski’s method, 07.16 ± 0.28 and 09.56 ± 0.28 µg/mL of IAA could be detected in the samples prepared from P. aeruginosa supplemented with 5 mg/mL CNPs and 100 µg/mL AuNPs, respectively. HPLC analysis also confirmed the production of IAA by P. aeruginosa. The CNPs and AuNPs-supplemented P. aeruginosa was also found to have enhancement effect on the shoot length (25.25 ± 0.85 cm and 26.57 ± 0.73 cm) and fresh weight (0.94 ± 0.09 g and 0.96 ± 0.09 g) of Vigna unguiculata plants, which highlight the significance of the study and the agricultural promises of nanomaterials-supplemented rhizobacteria.