Prodigiosin formation by Serratia marcescens in a chemostat

In a study of the control of metabolite formation, prodigiosin production by Serratia marcescens was used as a model. Specific production rates of prodigiosin formation were determined using batch culture technique. Sucrose as carbon source and NH₄NO₃ as nitrogen source resulted in a specific production rate of 0.476 mg prodigiosin (g cell dry weight)^?1 h^?1. Prodigiosin formation and productivity was inversely correlated to growth rate when the bacterium was grown under carbon limitation on a defined medium in a chemostat culture. The maximum specific growth rate (μ_max) was 0.54 h^?1 and prodigiosin was formed in amounts over 1 mg l^?1 up to a growth rate (μ) of 0.3 h^?1 at steady state conditions. At a dilution rate of 0.1 h^?1 growth at steady state with carbon and phosphate limitation supported prodigiosin formation giving a similar specific yield 1.17 mg prodigiosin (g cell dry weight)^?1 and 0.94 mg g^?1, respectively], however, cells grown with nitrogen limitation (NH₄)₂SO₄] did not form prodigiosin. Productivity in batch culture was 1.33 mg l^?1 h^?1 as compared to 0.57 mg l^?1 h^?1 in the chemostat.