Monday, August 13, 2012
Columbia Hall, Terrace Level (Washington Hilton)
Scale-up criterion of constant oxygen mass transfer coefficient(kLa) was applied for a successful production of itaconic acid(IA) in a 50L pilot-scale fermentor by the fungal cells of Aspergillus terreus. Various operating conditions were investigated to collect as many kLa data as possible by adjusting stirring speed and aeration rate in 5L and 50L fermentor systems. In the fermentations performed with the 5L fermentor, the highest IA production was observed under the operational conditions of 200rpm and 1.5vvm. Accordingly, in the 50L fermentor system we intended to find out the parallel agitation and aeration rates showing the almost equivalent value of kLa to that(0.02 sec-1) obtained from the 5L system. The conditions of 180rpm and 0.5vvm turned out optimal for supplying almost the same volumetric amount of dissolved oxygen(DO) into the 50L fermentaion broth as that observed in the 5L system, without causing shear damages to the producing cells due to excessive agitation. As a result, almost identical fermentation physiology could be obtained in the 5L and 50L cultures performed under those respective conditions. Especially, the almost same value of specific growth rate(μ) of the two cultures was impressive, in view of the fact that μ normally has a great influence on specific production rate(qp) in secondary metabolites production.