Influence of oxygen transfer on lipase production by Rhizopus arrhizus

The effect of oxygen on lipase production by Rhizopus arrhizus was studied under two operating modes, controlled dissolved oxygen concentration (DO) a nd controlled aeration rate. Lipase production depended more extensively on oxygen than cell growth. The intrinsic factor determining cell growth and lipase production was oxygen transfer rate (OTR) rather than DO concentrati on. Improvements in OTR, either by aeration or agitation or perfluorocarbon (PFC) inclusion resulted in an increase in lipase production. The formatio n of lipase could be described by a mixed-growth associated model. The over all productivity for the lipase which depended more strongly on agitation t han aeration could be related to the volumetric oxygen transfer coefficient , k(L)a. Addition of 10% (v/v) PFC to the fermentation medium also resulted in higher lipase production. (C) 2000 Elsevier Science Ltd. All rights res erved.