Cyclopropane fatty acids improve Escherichia coli survival in acidified minimal media by reducing membrane permeability to H+ and enhanced ability to extrude H+.
The physiological role of cyclopropane fatty acids (CFAs) in acid stress resistance was studied by in situ microelectrode H+ flux measurements of Escherichia coli Frag1 and its isogenic CFA-deficient mutant JBM 1. After exposure to pH 4 for 16h, net H+ influx in JBM 1 was twice that of the parent strain. H+ flux stabilisation at pH 6 after acid stress took more time in the cfa- mutant. The data suggest increased proton permeability and decreased ability to extrude H+ in the absence of CFA, and they support the hypothesis that CFAs protect E. coli in acidic environments by decreasing membrane permeability to H+.
Food Safety Centre, Tasmanian Institute of Agricultural Research, School of Agricultural Science, University of Tasmania, Private Bag 54, Hobart, Tas 7001, Australia.
Lana
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Shabala
Tom
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Ross
D000143:Acids / Q000378:metabolism*; D002463:Cell Membrane Permeability; D003470:Culture Media / Q000737:chemistry*; D003521:Cyclopropanes / Q000378:metabolism*; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability; D011522:Protons
D000143:Acids; D003470:Culture Media; D003521:Cyclopropanes; D005227:Fatty Acids; D011522:Protons; C028775:cyclopropane fatty acids