| Lactic acid fermentation for Rhizopus oryzae by immobilized cells with fibrous in a submerged membrane bioreactor was studied in this paper. The lactic acid fermentation was investigated in various culture conditions. The optimum preculture medium(g.L-1) was established, Glucose 60.0, NH4NO3 2.0, MgSO4 ·7H2O 0.25, NaH2PO4 0.3, ZnSO4·7H2O 0.05. The optimum culture condition was: 34℃, 100r.min-1, 30mL in a 250mL flask for 22h and adding CaCO3 7.0 g.L-1. The optimum production medium consisted of the following(g.L-1): Glucose 100, NH4NO3 2.0, MgSO4 ·7H2O 0.25, NaH2PO4 0.2, ZnSO4·7H2O 0.05. The effects of rotation speed and CaCO3 on immobilization were investigated. With 100r.min-1 and adding CaCO3 7.0 g.L-1, the optimum morphology of Rhizopus oryzae would be controlled into supported pellets at the diameter less than 1.0 mm. The final concentration and productivity of lactic acid were 77.83 g.L-1 and 1.29 g.L-1.h-1 when the pellets were immobilized with fibrous in the SMBR. Based on these data, fermentation from xylose was studied. Then the production condition was obtained at aeration rate of 2 vvm and agitation rate of 50 r.min-1. In order to separate lactic acid online and ease the inhibitory effects of lactic acid on cell growth and product formation, anion-exchange resin D354 was used for the separation of lactic acid from cell-free fermentation broth. Comparing with Amberlite IRA-400, D290, 201×4, PVP, the maximum adsorption of D354 for lactic acid could be reached at 0.5482 g/g dry resin at pH 3, and 0.3202 g/g dry resin at pH 5. Static and dynamic studies on the adsorption capabilities of D354 resin for lactic acid were conducted. The effects of temperature and pH on lactic acid adsorption were also investigated in the presence of glucose, xylose and inorganic salt. The mixture of ammonia and NaCl was chosen as an optimal eluant, the elution yield was 77.42%. Based on all these data, Simultaneous continuous fermentation and separation of lactic acid from oxylose was carried.
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