OmpC and OmpF are required for growth under hyperosmotic stress above pH 8 in Escherichia coli

Abstract Aims:  To investigate the requirement of outer membrane porins for osmotic adaptation at alkaline pH in Escherichia coli . Methods and Results:  Escherichia coli mutants deficient in ompC , ompF and both genes were constructed and the growth of these mutants was observed at alkaline pH. The growth rate of the mutant deficient in both ompC and ompF was slower than that of the wild type and mutants deficient in one of these genes under hyperosmotic stress at pHs above 8·0. The decreased rate was recovered when a cloned ompC was introduced to the mutant, but the growth recovery with a cloned ompF was partial. Such growth diminution was not observed at pHs below 8·0. Conclusion:  OmpC and OmpF were shown to participate in hyperosmotic adaptation at alkaline pH in E. coli . Significance and Impact of the Study:  This study is the first report to demonstrate that OmpC and OmpF are required for hyperosmotic adaptation at pHs above 8·0, but not below 8·0.