Assessment of phosphate solubilization and indole acetic acid production in plant growth promoting bacteria isolated from green house soils of Gonju-Gun, South Korea

Buddhi Charana Walpola,K K I U Arunakumara

doi:10.4038/tare.v18i1.5322

Buddhi Charana Walpola, K K I U Arunakumara

Open Access

https://doi.org/10.4038/tare.v18i1.5322

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Abstract

Phosphate solubilizing and indole acetic acid (IAA) producing bacteria are considered to be beneficial microorganisms as they have a profound effect on plant growth. A total of 35 phosphate solubilizing bacterial strains were isolated and screened for the production of IAA. Two best performing Enterobacter species were selected and employed in elucidating their phosphate solubilizing potential and IAA production under different conditions. Both strains were found to increase available phosphorus content in the medium profusely (640 μg/ml in E. ludwigii and 621 μg/ml in E . hormaechei ). They recorded the maximum IAA production (240 and 332 μg/ml respectively in E. ludwigii and E . hormaechei ), in NB medium supplemented with tryptophan (0.8% and 0.6% respectively in E. ludwigii and E . hormaechei ) at 30oC. It is evident from results that both strains possess great potential to be developed as bio-fertilizers which could enhance soil fertility and plant growth through phosphate solubilization and IAA production.

Highlights

It is well known that a considerable number of bacterial species, which can be found in the plant rhizosphere, at root surfaces and in association with roots are able to improve the quality of plant growth directly and or indirectly
Isolation of phosphate solubilizing bacterial strains and screening for Indole-3 -acetic acid (IAA) production Thirty five bacterial strains (PSB 1 to Phosphate solubilizing bacterial (PSB) 35) which exhibited clear zones on the NBRIP agar plates were selected as phosphate solubilizing organisms and they were screened for IAA production
NB medium was the best medium for IAA production (142 μg/ml in E. ludwigii and 139 μg/ml in E. hormaechei) followed by NBRIP medium

Summary

Introduction

It is well known that a considerable number of bacterial species, which can be found in the plant rhizosphere, at root surfaces and in association with roots are able to improve the quality of plant growth directly and or indirectly. They are called as “plant growth promoting rhizobacteria” (PGPR). Indole-3 -acetic acid (IAA), the most abundant member of the auxins family of phytohormones has many roles in important physiological processes including root initiation, cell enlargement and division, tissue differentiation, and responses to light and gravity (Teale et al, 2006). Plant growth-promoting rhizobacteria predominantly synthesize IAA as secondary metabolites through tryptophan dependent pathway (Ahmad et al, 2005; Mandal et al, 2007)

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