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Ion transport and osmotic adjustment in Escherichia coli in response to ionic and non-ionic osmotica


Shabala, Lana and Bowman, JP and Brown, JL and Ross, T and McMeekin, TA and Shabala, SN, Ion transport and osmotic adjustment in Escherichia coli in response to ionic and non-ionic osmotica, Environmental Microbiology, 11, (1) pp. 137-148. ISSN 1462-2912 (2009) [Refereed Article]

DOI: doi:10.1111/j.1462-2920.2008.01748.x


Bacteria respond to osmotic stress by a substantial increase in the intracellular osmolality, adjusting their cell turgor for altered growth conditions. Using Escherichia coli as a model organism we demonstrate here that bacterial responses to hyperosmotic stress specifically depend on the nature of osmoticum used. We show that increasing acute hyperosmotic NaCl stress above ∼1.0 Os kg-1 causes a dose-dependent K+ leak from the cell, resulting in a substantial decrease in cytosolic K+ content and a concurrent accumulation of Na+ in the cell. At the same time, isotonic sucrose or mannitol treatment (non-ionic osmotica) results in a gradual increase of the net K+ uptake. Ion flux data are consistent with growth experiments showing that bacterial growth is impaired by NaCl at the concentration resulting in a switch from net K+ uptake to efflux. Microarray experiments reveal that about 40% of upregulated genes shared no similarity in their responses to NaCl and sucrose treatment, further suggesting specificity of osmotic adjustment in E. coli to ionic and non-ionic osmotica. The observed differences are explained by the specificity of the stress-induced changes in the membrane potential of bacterial cells highlighting the importance of voltage-gated K+ transporters for bacterial adaptation to hyperosmotic stress. © 2008 The Authors.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Bacteriology
Objective Division:Health
Objective Group:Public health (excl. specific population health)
Objective Field:Food safety
UTAS Author:Shabala, Lana (Associate Professor Lana Shabala)
UTAS Author:Bowman, JP (Associate Professor John Bowman)
UTAS Author:Brown, JL (Dr Janelle Brown)
UTAS Author:Ross, T (Professor Tom Ross)
UTAS Author:McMeekin, TA (Professor Thomas McMeekin)
UTAS Author:Shabala, SN (Professor Sergey Shabala)
ID Code:53386
Year Published:2009
Web of Science® Times Cited:85
Deposited By:Agricultural Science
Deposited On:2008-12-04
Last Modified:2015-02-02

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