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Open Access Highly Accessed Research article

Staphylococcus aureus requires cardiolipin for survival under conditions of high salinity

Melody Tsai1, Ryosuke L Ohniwa1, Yusuke Kato2, Sayaka L Takeshita1, Toshiko Ohta1, Shinji Saito1, Hideo Hayashi3 and Kazuya Morikawa1*

Author Affiliations

1 Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8575, Japan

2 Division of Insect Sciences, National Institute of Agrobiological Sciences, Oowashi 1-2, Tsukuba 305-8634, Japan

3 Chugoku Gakuen University, Niwase 83, Kitaku, Okayama 701-0197, Japan

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BMC Microbiology 2011, 11:13  doi:10.1186/1471-2180-11-13

Published: 18 January 2011

Abstract

Background

The ability of staphylococci to grow in a wide range of salt concentrations is well documented. In this study, we aimed to clarify the role of cardiolipin (CL) in the adaptation of Staphylococcus aureus to high salinity.

Results

Using an improved extraction method, the analysis of phospholipid composition suggested that CL levels increased slightly toward stationary phase, but that this was not induced by high salinity. Deletion of the two CL synthase genes, SA1155 (cls1) and SA1891 (cls2), abolished CL synthesis. The cls2 gene encoded the dominant CL synthase. In a cls2 deletion mutant, Cls1 functioned under stress conditions, including high salinity. Using these mutants, CL was shown to be unnecessary for growth in either basal or high-salt conditions, but it was critical for prolonged survival in high-salt conditions and for generation of the L-form.

Conclusions

CL is not essential for S. aureus growth under conditions of high salinity, but is necessary for survival under prolonged high-salt stress and for the generation of L-form variants.