Diversity of prodigiosin content in the stationary phase organisms of Serratia marcescens fractionated by Ficoll density gradient centrifugation

A protein associated with prodigiosin formation in Serratia marcescens

A protein associated to prodigiosin formation was found in Serratia marcescens. The protein was not found in nonpigmented strains and was correlated with the pigment level. The protein was about 100 kilodaltons (kDa) and was also found in nonpigmented bacteria of the pigmented strain grown in glucose medium, at high temperature, or under anaerobic condition. The 100 kDa protein was found not in the outer membrane and the periplasm, but in the inner membrane and/or the cytoplasm. The protein was also found singly or dominantly in pigment-protein complexes and pigment-localizing vesicles described in previous reports. These results suggest that the 100 kDa protein is associated with prodigiosin formation.

Decrease in respiration activity related to prodigiosin synthesis in Serratia marcescens

Variation in the cell respiration rate of pigmented and nonpigmented strains of Serratia marcescens was exhibited. The respiration rate of a pigmented strain decreased earlier than that of nonpigmented strains in the late exponential or early stationary phase. However when prodigiosin synthesis was not induced by exchange of carbon sources in the medium, the decrease in the respiration rate of the pigmented strain was the same as that of nonpigmented strains. Measurement of the oxygen consumption rate in the sonicated cell membrane by adding NADH solution showed that the rate in the pigmented strain was lower than that in nonpigmented strains. Furthermore, the cell membrane of prodigiosin-induced organisms was more sensitive to respiration inhibitors than that of pigment-noninduced organisms of the pigmented strain. These results showed that the respiration activity was decreased by prodigiosin synthesis in S. marcescens.