Enhanced atrazine removal by hydrophyte–bacterium associations and in vitro screening of the isolates for their plant growth-promoting potential

ABSTRACT

Emergent hydrophytes Acorus calamus, Typha latifolia, and Phragmites karka and epiphytic root bacteria isolated from their rhizoplanes were exposed to atrazine (5 and 10 mg l⁻¹) individually and in plant-bacterium combination for 15 days hydroponically. It was observed that A. calamus-Pseudomonas sp. strain, the ACB combination, was best in decontamination, showing 91% and 87% removal of 5 and 10 mg l⁻¹ atrazine. Plant-bacterium association led to significant increase in atrazine decontamination as compared to decontamination by either plant or bacterium alone, indicating a synergistic action of the hydrophytes and isolates which led to enhanced atrazine removal. To the best of our knowledge this is the first report on the potential of plant–bacterium combinations for atrazine decontamination. The isolates showed augmented growth in the presence of plants and were able to alleviate atrazine stress in them. These isolates exhibited plant growth-promoting traits such as auxin, siderophore, Poly(3–hydroxybutyric acid)/succinogycan, ammonia, catalase production and solubilization of inorganic phosphate in vitro. The use of plant-bacterium mutualistic symbiosis for atrazine mitigation is a relatively simple, inexpensive, and clean technique and this phytoremediation-rhizoremediation combination is suggested to be tried on field to establish their potential for clean-up of contaminated sites.

KEYWORDS:

• Acorus calamus
• Phragmites karka
• phytoremediation
• plant growth-promoting rhizobacteria (PGPR)
• rhizoremediation
• Typha latifolia

Acknowledgment

The authors are thankful to Prof. J.–D. Gu, School of Biological Sciences, The University of Hong Kong, Hong Kong SAR, People's Republic of China, for his valuable input in writing this manuscript.

Funding

The authors acknowledge National Fund for Basic, Strategic and Frontier Application Research in Agriculture and Indian Council of Agricultural Research for funding the project Bioremediation of contaminants in polluted sites: Use of weedy plants for which the present study was conducted. Ms. Anina James is thankful to University Grants Commission (UGC) for providing fellowship as JRF/SRF.

Conflict of interest

No potential conflict of interest was reported by the authors.