Evaluation of mass transfer enhancement in lipase production by Yarrowia lipolytica in a multiphase system
Integration of life sciences & engineering
Bio-transformation in the Laboratory and in Large Scale Production (T5-3)
Keywords: Mass Transfer, Oxygen, Yarrowia lipolytica, Lipase
An alternative way to overpass the problem of oxygen limitation in aqueous aerobic fermentation is to add a second water-immiscible phase in which oxygen has a greater solubility, such as haemoglobin, hydrocarbons and perfluorocarbons (PFC).The present work shows that perfluorodecalin has a great effect in lipase production from Yarrowia lipolytica, with a 23 times increase in lipase productivity with the addition of 20% (v/v) PFC in 1-L flaks agitated at 250 rpm (Amaral et al., 2006). A variation in the PFC volume fraction permitted to observe that the benefit of PFC is maximized at 0.2, being approximately the same PFC volume fraction that promotes a maximum oxygen transfer rate (OTR) in other different systems (Cho and Wang, 1967; Elibol and Mavituna, 1999). Although there were reasons to believe that the factor which caused this increase in lipase productivity was the raise of OTR, there wasn’t enough proof of that. Therefore, the influence of oxygen transfer coefficient (kla) on lipase production from Yarrowia lipolytica in the presence of perfluorodecalin was investigated using a 2-L bioreactor. A polarographic oxygen electrode was employed to measure dissolved oxygen concentration in the liquid medium. The volumetric oxygen uptake rate and mass transfer coefficient were determined using the dynamic gassing-out method (Bandyopahyay and Humphrey, 1967). The equipment aeration efficiency was determined, in terms of kLa, varying air flow rate from 0.5 to 2.0 VVM, agitation speed from 160 to 350 rpm, impeller type and PFC concentration (0 to 30 % v/v). Some of the best conditions, in terms of kla, were chosen to evaluate the effects of oxygen and PFC concentrations in Yarrowia lipolytica’s growth and its lipase production. The intrinsic factor determining cell growth and lipase production was oxygen transfer rate (OTR) rather than DO concentration. Improvements in OTR, either by aeration, agitation or PFC concentration, resulted in an increase in lipase yield.
Amaral, P.F.F., Rocha-Leão, M.H.M., Marrucho, I.M., Coutinho, J.A.P, Coelho M.A.Z., Improving Lipase Production using a Perfluorocarbon as Oxygen Carrier, J Chem Technol Biotechnol, 81:1368–1374 (2006).
Bandyopahyay, B. and Humphrey, A. C., Dynamic measurements of the volumetric oxygen transfer coefficient in fermentation systems. Biotechnol Bioengn, 9:533-544 (1967).
Cho MH and Wang SS, Enhancement of oxygen transfer in hybridoma cell culture by using a perfluorocarbon as an oxygen carrier. Biotechnol Lett 10(12):855-860 (1988).
Elibol M and Mavituna F, A remedy to oxygen limitation problem in antibiotic production: addition of perfluorocarbon. Biochem Eng J 3:1-7 (1999).
Presented Thursday 20, 15:20 to 15:40, in session Bio-transformation in the Laboratory and in Large Scale Production (T5-3).
