Does hyperosmotic stress reduce bacterial growth rate by decreasing enzymatic velocity?*

The relationship between osmotic stress and inhibition of bacterial growth is well established, but not understood. Here, we present evidence that, unlike changes in the nutrient environment, osmotic stress does not significantly affect the ribosomal content, and instead leads to a reduction in the rate of enzymatic activity. Using a combination of in-vitro and in-vivo assays we attempt to measure the enzymatic activity of LacZ exponentially growing cells and show that a decrease in enzymatic velocity can potentially explain the observed growth rate reduction.