Growth of a proline hyperproducing strain of E. coli expressing a mutated version of the listerial proB gene relative to a wild-type E. coli in M9 minimal medium of elevated osmolarity. Growth (as determined by turbidity using a Spectra max 340 spectrophotometer, Molecular Devices), was measured both in the presence (closed symbols) and absence (open symbols) of 4% NaCl. (□, ▪) CSH26C control strain, (Δ, ▴) CSH26pro. Each point represents the mean value of three independent experiments.
