The reason that immobilized cells can be used several times is due to the fact that the mixing in the stirred tank fermenter provided a good mass transfer withoutcausing a clogging problem from biofilm formation on the chi-tosan surface. Moreover, no foam formation problem was foundduring fermentation which confirmed the anti-foaming propertyof chitosan. The presence of chitosan flakes in the culture mediuminterrupted the aggregation of air bubbles and lipopeptide, therebypreventing foam formation in the reactor. Other bioreactors forlipopeptide production such as rotating disc bioreactors [13] andbubbleless membrane bioreactors [11] can prevent foam forma-tion, however they showed the formation of biofilm on rotatingdisc and the adsorption of lipopeptide on the membrane, resultingin the requirement of washing step for both bioreactors.