Journal of Environmental Biology

Perspective of nitrate assimilation and bioremediation in Spirulina platensis (a non-nitrogen fixing cyanobacterium): An overview

Q. Fariduddin¹* , P. Varshney¹ and? A. Ali²

¹Plant Physiology and Biochemistry Section, Department of Botany, Aligarh Muslim University, Aligarh-202 002, India

²Department of Life Sciences, University of Mumbai, Mumbai-400 098, India

*Corresponding Author E-mail: qazi_farid@yahoo.com

Key words

NiR operon

Nitrate assimilation

Nitrate reductase

S. platensis

Publication Data

Paper received : 07.10.2015

Revised received : 29.11.2016

Re-revised received : 19.05.2017

Accepted : 18.08.2017

Abstract

Cyanobacterium, Spirulina platensis, has been used for many centuries as a food product and also has important applications in industry and environmental remediation. Apart from being a very good source of essential nutrients such as provitamins, minerals, polyunsaturated fatty acids, S. platensis is also characterized by its high protein content. The nitrate assimilation genes of S. platensis is organised in a systemic operon with the structure: nirA (nitrite reductase)?permease gene(s)?narB (nitrate reductase). Genomic localisation in S. platensis is different from the operons found in other cyanobacteria due to the presence of both types of nitrate transporters (nrtP and ABC types). Both nitrate uptake and transcription of the nitrate assimilatory genes in S. platensis are regulated. However, the mechanism of regulation of nitrate assimilatory genes is different from other non-nitrogen fixing cyanobacterial species. In the last decade, it has also been exploited for its capacity to decontaminate water and environmental pollution caused by hazardous materials. Role of S. platensis in removal of toxic metal ions from the polluted effluent have taken more importance in this area because of their small size have a high surface area-to-volume ratio and therefore provide a large contact area for metal binding. The biosorption processes have been studied extensively using S. platensis microbial biomass as biosorbent for heavy metal ions removal because of adherent advantage of mass cultivation. All of these desirable physiological characteristics and applications have made S. platensis as a model organism to understand nitrogen metabolism. This review deals with recent advances in the characterization of nitrate assimilation and bioremediation potential of S. platensis.

Copyright ? 2018 Triveni Enterprises. All rights reserved. No part of the Journal can be reproduced in any form without prior permission. Responsibility regarding the authenticity of the data, and the acceptability of the conclusions enforced or derived, rest completely with the author(s).