Evaluation of Fixed-Bed Cultures with Immobilized Lactococcus Lactis ssp. Lactis on Different Scales

Abstract

Fixed-bed processes, where cells are immobilized within macroporous carriers, are a promising alternative to processes with suspended cells. A scale-up concept is presented in order to evaluate the performance as part of process design of fixed-bed processes. Therefore, Lactococcus lactis cultivation in chemostat and batch mode was compared to fixed bed cultures on three different scales, the smallest being the downscaled Multiferm with 10 mL fixed bed units, the second a 100 mL fixed-bed reactor and the third a pilot scale reactor with 1 L fixed bed volume. As expected, the volume specific lactate productivity of all cultivations was dependent on dilution rate. In suspension chemostat culture a maximum of 2.3 g·L -1 ·h -1 was reached. Due to cell retention in the fixed-beds, productivity increased up to 8.29 g·L -1 ·h -1 at a dilution rate of D = 1.16 h -1 (corresponding to 2.4·µ max ) on pilot scale. For all fixed bed cultures a common spline was obtained indicating a good scale-up performance.

Design and Operation of Fixed-Bed Bioreactors for Immobilized Bacterial Culture

“…For all three fixed-bed bioreactor systems (Multiferm 10 mL, axial flow 100 mL, radial flow 1 L), a "proof of concept" has been shown before [6,9,10]. More infos on Materials and Methods can be found there.…”

“…The next step is an axial-flow 100 mL fixed-bed system, which can be operated continuously with reasonable effort to investigate the performance and long-term stability of the culture [6]. As a first approach for scale-up, a radial-flow 1 L fixed-bed reactor is applied [6,10]. Even if this is probably not the final industrial scale, the reactor system has already been the main characteristics of a large-scale system, mainly the radius.…”

“…For further increase of the volume, just the height has to be increased [11]. For all three systems, a "proof of concept" has been shown before [10]. In Chapter 4 the performance of these three fixed-bed systems is compared for fixed-bed cultures of LABs.…”

“…Fixed-bed and suspension cultures of L. lactis were compared with respect to the volume-specific lactate productivity ( Figure 6) [10]. Continuous suspension culture in chemostat mode showed the expected course [20].…”