Figure 1. Effect of different sugar concentrations on the production of citric acid by Aspergillus niger GCMC-7 in stirred fermentor.

Agitation intensity: 200 rpm.
Air supply: 1.0 l/l/min.
Initial pH: 6.0.
Incubation temperature: 30ºC.
Fermentation period: 168 h.
The error bars indicate the standard deviation among the three parallel replicates.