Strategy of Two-Stage Agitation Rate for Citric Acid Production

Abstract:

The effects of agitation seed on the growth of Aspergrillus niger CCTCC M2013172, citric acid production,dissolved oxygen and residual sugar were studied in a 3 L batch fermenter in this study. The results revealed that 500 r/min was the relative optimal condition and under this condition the yield of citric acid is 12.9 g/L,the conversion rate is 86% and the biomass is 42.6 g/ L.Base on the result,a two-stage agitation ratecontrolling strategy was proposed,in which agitation rate was controlled at 600 r/min in the first 16 h and then switched to 500 r/min after wards. By this controlling strategy,the yield of citric acid reached 14 g/L,the conversion rate reach to 94.6%. And then the two-stage agitation rate controlling strategy was combined with fed-batch fermentation technology,and the yield of citric acid reached 17.2 g/L,the conversion rate reached 95.5%.