Polysaccharide production of Neisseria meningitidis(Serogroup C)in batch and fed-batch cultivations

摘要

Serogroup C polysaccharide from Neisseria.meningitidis constitutes the antigen for the vaccine against the disease caused by this bacterium.Aiming at enhancing the final polysaccharide concentration as well as the overall yield factor(polysaccharide/biomass),20 cultivations were carried out in Frantz medium in a 13 L bioreactor at 35 deg C,0.5 atm,400 rpm and air flowrate of 2 L/min.A series of nine batch experiments was carried out under three different conditions(with control of dissolved oxygen at 10%,with control of pH at 6.5 and without dissolved oxygen and pH controls).Another set of runs consisted of 11 fed-batch cultivations without dissolved oxygen control,varying glucose concentration from less than 1.0-3.0 g/L,four of which performed controlling the pH at 6.5,and four under partial fed-batch conditions.The highest polysaccharide concentration(0.26 g/L)and the overall yield(0.16 g/g),were obtained in batch and partial fed-batch experiments when glucose concentration was maintained below 1.0 g/L.An empirical relation is proposed to relate the specific production rate of polysaccharide to glucose concentration during the stationary growth phase of the fed-batch runs.The obtained polysaccharide satisfies the molecular weight criterion,being a suitable antigen for vaccine production.