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Front. Microbiol. | doi: 10.3389/fmicb.2019.01207

Halomonas Rhizobacteria of Avicennia marina of Indian Sundarbans Promote Rice Growth under Saline and Heavy Metal Stresses through Exopolysaccharide Production

  • 1Department of Biotechnology, Techno India Group (India), India
  • 2Department of Marine Science, University of Calcutta, India
  • 3Department of Microbiology, Bose Institute, India

The Halomonas species isolated from the rhizosphere of the true mangrove Avicennia marina of Indian Sundarbans showed enhanced rice growth promotion under combined stress of salt and arsenic in pot assay. Interestingly, under abiotic stress conditions, Halomonas sp. Exo1 was observed as an efficient producer of exopolysaccharide. The study revealed that salt triggered exopolysaccharide production, which in turn, increased osmotic tolerance of the strain. Again, like salt, presence of arsenic also caused increased exopolysaccharide production that in turn sequestered arsenic showing a positive feedback mechanism. To understand the role of exopolysaccharide in salt and arsenic biosorption, purified exopolysaccharide mediated salt and arsenic sequestration were studied both under in vivo and in vitro conditions and the substrate binding properties were characterized through FT-IR and SEM-EDX analyses. Further, enhanced plant growth was revealed in the presence of the strain and pure exopolysaccharide individually in pot assay, confirming direct role of exopolysaccharide in plant growth promotion.

Keywords: abiotic stress, arsenic bioremediation, Exopolysaccharide, Halomonas, rhizobacteria, rice growth promotion, salt sequestration, true mangrove Avicennia marina

Received: 21 Oct 2018; Accepted: 13 May 2019.

Edited by:

Heike Bücking, South Dakota State University, United States

Reviewed by:

Doan Trung Luu, Centre National de la Recherche Scientifique (CNRS), France
Puneet S. Chauhan, National Botanical Research Institute (CSIR), India
Maqshoof Ahmad, University College of Agriculture & Environmental Sciences, Islamia University of Bahawalpur, Pakistan  

Copyright: © 2019 Mukherjee, Mitra and Roy. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Madhumita Roy, Bose Institute, Department of Microbiology, Kolkata, India, roymadhumita@rediffmail.com