Evaluation of Plant Growth-Promoting and Salinity Ameliorating Potential of Halophilic Bacteria Isolated From Saline Soil

Chintan Kapadia; Nafisa Patel; Ankita Rana; Harihar Vaidya; Saleh Alfarraj; Mohammad Javed Ansari; Abdul Gafur; Peter Poczai; R Z Sayyed

doi:10.3389/fpls.2022.946217

Evaluation of Plant Growth-Promoting and Salinity Ameliorating Potential of Halophilic Bacteria Isolated From Saline Soil

Front Plant Sci. 2022 Jul 15:13:946217. doi: 10.3389/fpls.2022.946217. eCollection 2022.

Authors

Chintan Kapadia¹, Nafisa Patel², Ankita Rana², Harihar Vaidya¹, Saleh Alfarraj³, Mohammad Javed Ansari⁴, Abdul Gafur⁵, Peter Poczai⁶, R Z Sayyed^{7

8}

Affiliations

¹ Department of Plant Molecular Biology and Biotechnology, ASPEE College of Horticulture and Forestry, Navsari Agricultural University, Navsari, India.
² Naran Lala College of Professional and Applied Sciences, Navsari, India.
³ Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia.
⁴ Department of Botany, Hindu College (Mahatma Jyotiba Phule Rohilkhand University Bareilly), Moradabad, India.
⁵ Sinarmas Forestry Corporate Research and Development, Perawang, Indonesia.
⁶ Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland.
⁷ Department of Entomology, Asian PGPR Society for Sustainable Agriculture, Auburn University, Auburn, AL, United States.
⁸ Department of Microbiology, PSGVP Mandal's'S I Patil Arts, G B Patel Science, and STKV Sangh Commerce College, Shahada, India.

Abstract

Among the biotic and abiotic stress affecting the physical, chemical, and biological properties of soil, salinity is a major threat that leads to the desertification of cultivable land throughout the world. The existence of diverse and versatile microbial populations inhabiting the nutrient-rich soil and varied soil conditions affects the soil dynamism. A normal soil constitutes 600 million bacteria belonging to about 20,000 species, which is reduced to 1 million with 5,000-8,000 species in stress conditions. Plant growth-promoting rhizobacteria (PGPR) are in symbiotic association with the plant system, which helps in combating the abiotic stress and increases the overall productivity and yield. These microorganisms are actively associated with varied cellular communication processes through quorum sensing and secondary metabolites such as the production of Indole-3-acetic acid (IAA), exopolysaccharide (EPS) siderophore, ammonia, ACC deaminase, and solubilization of phosphate. The present study focused on the isolation, identification, and characterization of the microorganisms isolated from the seacoast of Dandi, Navsari. Twelve isolates exhibited PGP traits at a high salt concentration of 15-20%. AD9 isolate identified as Bacillus halotolerans showed a higher ammonia production (88 ± 1.73 μg/mL) and phosphate solubilization (86 ± 3.06 μg/mL) at 15% salt concentration, while AD32^* (Bacillus sp. clone ADCNO) gave 42.67 ±1.20 μg/mL IAA production at 20% salt concentration. AD2 (Streptomyces sp. clone ADCNB) and AD26 (Achromobacter sp. clone ADCNI) showed ACC deaminase activity of 0.61 ± 0.12 and 0.60 ± 0.04 nM α-ketobutyrate/mg protein/h, respectively. AD32 (Bacillus sp. clone ADCNL) gave a high siderophore activity of 65.40 ± 1.65%. These isolates produced salinity ameliorating traits, total antioxidant activities, and antioxidant enzymes viz. superoxide dismutase (SOD), Glutathione oxidase (GSH), and catalase (CAT). Inoculation of the multipotent isolate that produced PGP traits and salinity ameliorating metabolites promoted the plant growth and development in rice under salinity stress conditions. These results in 50% more root length, 25.00% more plant dry weight, and 41% more tillers compared to its control.

Keywords: ACC deaminase; IAA; PGPR; abiotic stress; antioxidant enzymes; biofilm; microbial diversity; saline soil.