FIG. 1.

Expression of cspD in C. crescentus NA1000. (A) β-Galactosidase activity assay with wild-type strain NA1000 harboring plasmid pEL4. The cells were grown in different media: G, M2G (containing 0.2% glucose); X, M2X (glucose was replaced by 0.3% xylose); P, M2P (glucose was replaced by 0.2% peptone); GP, M2GP (containing both glucose and peptone). Cultures were incubated at 30°C, and the expression of cspD was determined at mid-exponential phase (white bars), after 24 h (light gray bars), and after 48 h (dark gray bars). (B) Growth curves of C. crescentus NA1000 harboring pEL4 in different media. (C) Expression of cspD in NA1000(pEL4) was determined by β-galactosidase activity assays at mid-exponential phase in M2 medium containing 0.2% glucose (white bars) and at several time points after washing and inoculation in M2 medium containing 0.02% glucose (gray bars). (D) β-Galactosidase activity was determined at mid-exponential phase in M2 medium containing NH₄Cl (white bars) and at several time points after washing and inoculation in M2 medium without NH₄Cl (gray bars). Error bars indicate standard deviations.