Raden Darmawan, Tri Widjaja, Setiyo Gunawan : Continuous Ethanol Production with Immobilized Ca-Alginate Cells Technique in Packed Bed Bioreactor using Bacteria : Z. mobilis and Mutated Z.mobilis
Raden Darmawan S.T., M.T.
Prof. Dr. Ir. Tri Widjaja M.Eng.
Setiyo Gunawan S.T., Ph.D
Zymomonas mobilis possesses many advantages for ethanol production including higher substrate
conversion and high ethanol tolerance. Zymomonas mobilis mutated by hydroxylamine has ability to
achieve a faster conversion and more resistant to acidic conditions. These bacteria were used in
fermentation with immobilized cells technique. Immobilized cell technique is a cell-entrapment technique
in order to keep the cells stay in the bioreactor so that it is able to optimally produce ethanol. The cells were
immobilized using Ca-alginate as the supporting matrices. This research aims to find out the influence of
glucose concentration using both z.mobilis and mutated z.mobilis on the performance of ethanol
production in packed bed bioreactor in order to enhance the concentration, yield, and ethanol productivity,
respectively. The ethanol production used molasses as raw material by fermentation process in the packed
bed bioreactor. The experiment was started by making starter, molasses pretreatment, culture growth,
making production medium, and making immobilized Ca-Alginate cells. Immobilized cells have sphericalshape
with diameter of 2 mm and weight of 220 g. Having prepared beads, the fermentation was performed
in the packed bed bioreactor by flowing molasses using peristaltic pump under the flow rate condition of
0.154 L/hr (dilution rate of 0.75 hr-1 ). Ethanol product (broth) was analyzed by gas chromatography (GC)
method. It was shown from the result that maximum ethanol production conducted using mutated z.mobilis
gave the following concentration, yield, and productivity: 73.26 g/L, 40.96 %, 54.95 g/L.hr, respectively.
While the result of ethanol production conducted using z.mobilis gave the following concentration, yield,
and productivity: 62.17 g/L, 36.85 %, 46.63 g/L.hr, respectively.