ENHANCEMENT OF LIPASE PRODUCTION DURING REPEATED BATCH CULTURE USING IMMOBILIZED CANDIDA-RUGOSA

Batch and repeated batch (fed-batch type) experiments were carried out for lipase production using immobilised Candida rugosa cells in packe d-bed bioreactors (PER). Among the immobilising agents tested, namely agar, calcium alginate and polyacrylamide, calcium alginate was found to be the most suitable gelling agent with a cell loading of 10 mg cel ls (wet wt) per g of gelling agent. When the substrate was recycled, t he lipase yield increased, indicating better utilization of the substr ate. Addition of fatty acids at 0.75 g/litre improved the enzyme yield and caprylic acid proved to be the best in this regard (14.9 U of lip ase at 36 h). Supplementing the medium with gum arabic in combination with caprylic acid further improved the lipase yield. Maximum enzyme ( 17.94 U/ml) was produced when the fermentation was carried out in a PE R in repeated-batch mode using a feed medium containing gum arabic and caprylic acid, keeping the flow rate of the feed at 0.4 ml/min and al lowing each cycle to persist for 12 h. (C) 1997 Elsevier Science Ltd.