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International Journal of Microbiology
Volume 2013 (2013), Article ID 312146, 6 pages
Research Article

Antioxidant Functions of Nitric Oxide Synthase in a Methicillin Sensitive Staphylococcus aureus

Microbiology and Immunology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, 800 West Jefferson Street, Kirksville, MO 63501, USA

Received 22 January 2013; Accepted 11 March 2013

Academic Editor: John Tagg

Copyright © 2013 Manisha Vaish and Vineet K. Singh. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Nitric oxide and its derivative peroxynitrites are generated by host defense system to control bacterial infection. However certain Gram positive bacteria including Staphylococcus aureus possess a gene encoding nitric oxide synthase (SaNOS) in their chromosome. In this study it was determined that under normal growth conditions, expression of SaNOS was highest during early exponential phase of the bacterial growth. In oxidative stress studies, deletion of SaNOS led to increased susceptibility of the mutant cells compared to wild-type S. aureus. While inhibition of SaNOS activity by the addition of L-NAME increased sensitivity of the wild-type S. aureus to oxidative stress, the addition of a nitric oxide donor, sodium nitroprusside, restored oxidative stress tolerance of the SaNOS mutant. The SaNOS mutant also showed reduced survival after phagocytosis by PMN cells with respect to wild-type S. aureus.