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.