Comparative nitrogen fixation by mesophilic (HTS) vis-à-vis thermotolerant mutants (HTR) of Azotobacter chroococcum at high temperature and their effect on cotton biomass

Arpana Mittal; Anita Yadav; Gulab Singh; Ramesh Chand Anand; Neeraj Aggarwal

Jundishapur Journal of Microbiology

Ahvaz Jundishapur University of Medical Sciences

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Comparative nitrogen fixation by mesophilic (HTS) vis-à-vis thermotolerant mutants (HTR) of Azotobacter chroococcum at high temperature and their effect on cotton biomass

Author(s):

Arpana Mittal¹,

Anita Yadav²,

Gulab Singh¹,

Ramesh Chand Anand³,

Neeraj Aggarwal^1,*

1Department of Microbiology, Kurukshetra University, Kurukshetra, Haryana, India

2Department of Biotechnology, Kurukshetra University, Kurukshetra, Haryana, India

3Department of Microbiology, CCS Haryana Agricultural University Hisar, Haryana, India

Jundishapur Journal of Microbiology:Vol. 4, issue 2; e94132

Published online:Apr 30, 2011

Article type:Research Article

Received:May 20, 2019

Accepted:Apr 30, 2011

How to Cite:Arpana MittalAnita YadavGulab SinghRamesh Chand AnandNeeraj AggarwalComparative nitrogen fixation by mesophilic (HTS) vis-à-vis thermotolerant mutants (HTR) of Azotobacter chroococcum at high temperature and their effect on cotton biomass.Jundishapur J Microbiol.4(2):e94132.

Abstract

Introduction and objective: The amount of nitrogen fixed by Azotobacter varied from 0.02-0.25 KgN/ha/d and has been reported to be variable with various physiological and environmental factors. The nitrogen fixation by mesophilic soil isolates and their analogue resistant mutants of Azotobacter chroococcum was compared with their thermotolerant mutants at three different temperatures (30oC, 37oC, 42oC).

Material and methods: Mutants spontaneously resistant to methylammonium chloride were derived originally from a soil isolate of A. chroococcum. Ammonia excretion ability of different strains of A. chroococcum was determined by the method of Chaney and Marbach (1962). Nitrogenase activity of different strains of A. chroococcum was assayed by growing the cultures in the Burk medium. Effect of Azotobacter inoculation on cotton biomass was followed.

Results: Growth and ammonia excretion were related in both mesophilic as well as thermotolerant mutants at 30oC but not at elevated temperature (42oC). A thermotolerant strain (HTR71) has excreted as much as 24.1µg ammonia/ml of culture broth in a sucrose supplemented synthetic Jensen’s medium at elevated temperature of 37oC under stationary conditions of growth while a thermotolerant mutant (HTR54) showed nitrogenase activity of 46.13 nmoles C2H4 /h/mg protein at 37oC while Mac68, a mesophilic strain from which HTR54 is derived by mutation has nitrogenase activity of 35.07 nmoles C2H4 /h/mg protein. Thermotolerant mutants showed better performance over mesophilic strains on the cotton biomass under pot house conditions.

Keywords

Azotobacter chroococcum

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