Delineating Kocuria turfanensis 2M4 as a credible PGPR: a novel IAA-producing bacteria isolated from saline desert

Abstract

Indole-3-acetic acid (IAA)-producing bacteria Kocuria turfanensis strain 2M4 was isolated from the rhizospheric soil of halotolerant plant Suaeda fruticosa from a unique saline desert of Little Rann of Kutch, Gujarat, India. Rhizobacteria was bright orange pigmented, gram-positive, coccoid, non-endospore forming, and aerobic in nature. 16S rRNA gene sequence analysis showed that 2M4 isolate matched best with type strain of K. turfanensis HO-9042^T. Isolate optimally produced 38 µg ml⁻¹ IAA when growth medium was supplemented with 600 µg ml⁻¹ of L-tryptophan. Thin layer chromatography and Fourier transform infrared spectroscopy analysis were performed to corroborate IAA production. To characterize rhizobacterial isolate as a plant growth-promoting bacteria, it was tested for phosphate solubilization where it solubilized maximum 12 µg ml⁻¹ phosphate in presence of fructose, produced 53% siderophore units under iron-free minimal MM9 medium and produced 1.8 µmol ml⁻¹ ammonia in peptone water broth. Plant growth promotion by test isolate was studied on groundnut (Arachis hypogaea L.) under non-saline and saline soil. There was increase by 18% in total plant length and 30% in fresh biomass observed under non-saline control soil. Under saline soil, test isolate showed 17% increase in total length of the plant and 13% increase in fresh biomass.

Keywords:

• Kocuria turfanensis
• indole-3-acetic acid (IAA)
• Fourier transform infrared spectroscopy (FTIR)
• thin layer chromatography (TLC)
• Little Rann of Kutch

Acknowledgments

Authors are thankful to Department of Science and Technology (DST), New Delhi, India for the fellowship and financial aid. Authors are also thankful to Dr. K. C. Patel R&D Centre, Charotar University of Science and Technology (CHARUSAT) for providing necessary facilities.