Multi-Fixed-Bed Bioreactor System Applied for Bioprocess Development of Immobilized Lactic Acid Bacteria

Abstract

Abstract:The multi-fixed-bed bioreactor "Multiferm" provides a downscaled system for the development of fixed-bed processes with immobilized microorganisms or cells. It consists of twelve single fixed-bed units that can be operated independently. Different bacterial strains, carriers used for immobilization, media or flow rates can be studied in one compact experimental set-up. Experiments can be run in parallel to allow for determination of experimental errors. In these studies several continuous cultivations were carried out with Lactobacillus delbrueckii ssp. bulgaricus using different dilution rates and culture durations as proof-ofconcept for the Multiferm. Parameters relevant for process design such as reproducibility of simultaneously performed cultures, optimal dilution rate and long-term performance were determined by means of volume specific lactate and biomass productivity. First indications on a reduced growth rate of the cells due to immobilization were found.

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

“…(1)). This bioreactor system was established and precisely described previously [17,20]. Each unit was filled with borosilicate carriers (VitraPOR ® , ROBU ® Glasfilter-Geräte GmbH) with a mean diameter of 4 mm.…”

“…The first, very small scale of 10 mL working volume is the multi-fixed-bed bioreactor "Multiferm". We recently reported on the successful application of this system for the first evaluation of process parameters and kinetic modelling [17]. The next step is a 100 mL fixed-bed system, which can be operated continuously with reasonable effort to investigate the performance and long-term-stability of the culture.…”

“…For all the three systems, a "proof-of-concept" has been shown before [7,17]. The aim of the study presented here was to compare the performance of these three fixed-bed systems with Lactococcus lactis ssp.…”

Experimental Investigation and Reaction Kinetics Modeling of Biomass Formation, Substrate Consumption and Product Formation During Startup of Fixed-Bed Cultures with Immobilized Lactococcus lactis ssp. lactis

“…All samples except for retained biomass were withdrawn at the outlet (harvest flow) of each fixed-bed unit. This reactor system was established and precisely described in a previous study using a Lactobacillus strain [29].…”

“…It consists of twelve single fixed-bed units that can be operated independently [29]. As experiments can be run in parallel, it offers the possibility to determine the progress of biomass formation by analyzing some of the fixed-bed units at different time points.…”