Continuous Fermentation of a Prodigiosin-Producing Serratia marcescens Strain Isolated from Soil

A red-pigmented bacterial strain NS-17 was isolated from soil, and physiological and biochemical characteristics and 16S rDNA analysis established this organism as a strain of Serratia marcescens. The red pigment isolated from cells of NS-17 was identified as prodigiosin. By analyzing factors affecting the production of prodigiosin, modified medium and culture conditions were set up, and a continuous fermentation method was carried out to take advantage of the mass production of foam during fermentation. Continuous fermentation was achieved in the following conditions: 32℃, 1:1 ventilation ratio, and medium with a nutrient concentration 5-fold higher than that of the fermentation medium (with half the inorganic salt concentration) supplied as a feed medium at a flow rate of 8 mL/min. For the first time of continuous fermentation of Serratia marcescens coupling with foam flotation, a high yield of prodigiosin was obtained. After 56 h of culturing, the total harvest of cells was enhanced 2.33-fold compared to that of batch fermentation, the total amount of prodigiosin was enhanced 2.70-fold compared to that of batch fermentation, and cells and prodigiosin were concentrated in the efflux broth automatically.