Improving lipase production by nutrient source modification using Rhizopus homothallicus cultured in solid state fermentation

Rhizopus homothallicus (IRD13a) was cultivated for lipase production in solid state fermentation (SSF) using sugarcane bagasse as a support and impregnated with a liquid medium. The production of an extracellular lipase from Rh. homothallicus was improved by modification of media nutrients. The nutrients that mainly influenced growth and lipase production were urea, olive oil and oligo-elements. Kinetics of growth and lipase production were carried out using the improved medium. A correlation was found between the lipase production profile and the profiles Of CO2 production, O-2 consumption and pH changes. A maximum of 826 U/g DM was reached in only 12 h of incubation. This production represented a 60-fold increase of lipolytic activity compared to that obtained using a well known medium for lipase production. These results are promising because this strain produces high lipase concentrations in an inexpensive and simple medium, which facilitates its recovery and purification. Lipase extraction from the fermented solid was also studied. Efficient recovery of the enzyme was achieved using Triton X-100 at 0.5% (w/v). (c) 2006 Published by Elsevier Ltd