This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by El Hassan, G. A.
Right arrow Articles by Focht, D. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by El Hassan, G. A.
Right arrow Articles by Focht, D. D.
Agricola
Right arrow Articles by El Hassan, G. A.
Right arrow Articles by Focht, D. D.

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1985 March; 49(3): 517-521
Copyright © 1985, American Society for Microbiology. All Rights Reserved.

Kinetics of Denitrifying Growth by Fast-Growing Cowpea Rhizobia

G. A. El Hassan, R. M. Zablotowicz{dagger} and D. D. Focht*

Department of Soil and Environmental Sciences, University of California, Riverside, Riverside, California 92521

ABSTRACT

Two fast-growing strains of cowpea rhizobia (A26 and A28) were found to grow anaerobically at the expense of NO3–, NO2–, and N2O as terminal electron acceptors. The two major differences between aerobic and denitrifying growth were lower yield coefficients (Y) and higher saturation constants (Ks) with nitrogenous oxides as electron acceptors. When grown aerobically, A26 and A28 adhered to Monod kinetics, respectively, as follows: Ks, 3.4 and 3.8 µM; Y, 16.0 and 14.0 g · cells eq–1; µmax, 0.41 and 0.33 h–1. Yield coefficients for denitrifying growth ranged from 40 to 70% of those for aerobic growth. Only A26 adhered to Monod kinetics with respect to growth on all three nitrogenous oxides. The apparent Ks values were 41, 270, and 460 µM for nitrous oxide, nitrate, and nitrite, respectively; the Ks for A28 grown on nitrate was 250 µM. The results are kinetically and thermodynamically consistent in explaining why O2 is the preferred electron acceptor. Although no definitive conclusions could be drawn regarding preferential utilization of nitrogenous oxides, nitrite was inhibitory to both strains and effected slower growth. However, growth rates were identical (µmax, 0.41 h–1) when A26 was grown with either O2 or NO3– as an electron acceptor and were only slightly reduced when A28 was grown with NO3– (0.25 h–1) as opposed to O2 (0.33 h–1).

FOOTNOTES

* Corresponding author.

{dagger} Present address: Allied Chemical Co., Solvay, NY 13209.

Appl Environ Microbiol. 1985 March; 49(3): 517-521
Copyright © 1985, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»