A synthetic biological secondary metabolite, Lycogen™, produced and extracted from Rhodobacter sphaeroides WL-APD911 in an optimizatioal scale-up strategy

The optimization of fermentation medium is important for synthetic biological secondary metabolite productions. The effect of rotation speed, inoculum amount, and medium supplements on the cell growth and Lycogen™ secretion of photobacterium Rhodobacter sphaeroides WL-APD911 was evaluated. The results reveal that a higher rotational speed exhibit a higher cell density, and the increasing in the amount of inoculum amount show a slight augment on the growth of R. sphaeroides WL-APD911.In the case of nitrogen sources adding, Lycogen™ production was achieved with a 0.5 mM l-lysine supplementation. Moreover, the attention of Tween 80 presented a tremendous increase in the secondary metabolite. Response surface methodology (RSM) exhibited the optimization of medium supplements for Lycogen™ invention is accomplished at molasses concentration of 10 g/L, yeast extract concentration of 40 g/L, 0.3% Tween 80 and NaCl concentration of 5 g/L, respectively. Further, the batch fermentation is carried out in both 5 L and 20 L fermentors to study the scale-up process factors to be adopted. At a 20 L fermentor, Lycogen™ yields under the optimal culture condition are over 2 times than in the shake flask. The present results provide the Lycogen™ optimal culture mediums, scale-up procedures and efficient extractions from R. sphaeroides WL-APD911.