Screening and Optimization of Zinc Removal Potential in Pseudomonas aeruginosa-HMR1 and its Plant Growth-Promoting Attributes

Abstract

The soil samples of old Zawar mine sites were sandy texture, basic, electric conductivity range from 16 to 59 dSm^-1 with a high content of heavy metals of Zn, Pb, Cd, and Fe, indicating poor soil-health. Two bacterial isolates Pseudomonas aeruginosa HMR1 and P. aeruginosa HMR16 (GenBank-accession-number KJ191700 and KU174205, respectively), differed in the Phylogenetic tree based on 16S-rDNA sequences. HMR1 isolate showed the high potential of Plant growth-promoting attributes like IAA, Phosphate-solubilization, Exopolysaccharide production, and Proline activities at high concentration of Zn augmented nutrient media after 24 h, followed by HMR1 + HMR16 and HMR16. Both isolates were survived at 100 ppm Zn (w/v) concentration, followed by Pb, Cd, and Fe. Linear R_L value from Langmuir and Freundlich isotherms revealed that the suitable condition of Zn adsorption by HMR1 was at pH8 with 40°C. The value of r² from pseudo-second-order kinetics and Transmission-Electron-Microscopic analysis confirmed Zn adsorption by HMR1.

Keywords: First and second-order kinetics; Langmuir and Freundlich isotherms kinetics; Phylogenetic analysis; Plant growth-promoting attributes; Pseudomonas aeruginosa; Transmission-Electron-Microscope; Zn-adsorption.