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

Abstract

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 0.5mM 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 10g/L, yeast extract concentration of 40g/L, 0.3% Tween 80 and NaCl concentration of 5g/L, respectively. Further, the batch fermentation is carried out in both 5L and 20L fermentors to study the scale-up process factors to be adopted. At a 20L 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.