Monoclonal antibodies are conquering the biopharmaceutical market because they can be used to treat a variety of diseases. Therefore, it is very important to establish robust and optimized processes for their production. In this article, the first step of chromatography (Protein A chromatography) in monoclonal antibody purification was optimized with a focus on the critical elution step. Therefore, different buffers (citrate, glycine, acetate) were tested for chromatographic performance and product quality. Membrane chromatography was evaluated because it promises high throughputs and short cycle times. The membrane adsorber Sartobind^® Protein A 2 mL was used to accelerate the purification procedure and was further used to perform a continuous chromatographic run with a four-membrane adsorber-periodic counter-current chromatography (4MA-PCCC) system. It was found that citrate buffer at pH 3.5 and 0.15 M NaCl enabled the highest recovery of >95% and lowest total aggregate content of 0.26%. In the continuous process, the capacity utilization of the membrane adsorber was increased by 20%.

Continuous chromatography can surmount the disadvantages of batch chromatography like low productivities and extensive usage of consumables. In this work, a 4-column continuous chromatographic system based on the principle of periodic counter-current chromatography (PCCC) was developed and tested with a model protein mixture of BSA and lysozyme. The PCCC system was specially designed for membrane adsorbers as an alternative to conventional columns to facilitate the use of disposable process units and to further increase the productivity due to higher convective mass transport in the membrane adsorber. Membrane adsorber Sartobind^® Q was used to continuously purify BSA from the protein mixture. The usage of PCCC led to an increased capacity utilization (here 20%) and higher space–time-yields, and thus to a remarkable productivity increase and cost savings.

The patchoulol synthase (PTS) from Pogostemon cablin is a versatile sesquiterpene synthase and produces more than 20 valuable sesquiterpenes by conversion of the natural substrate farnesyl pyrophosphate (FPP). PTS has the potential to be used as a biocatalyst for the production of valuable sesquiterpenes such as (−)‐patchoulol. The objective of the present study is to develop an efficient biotransformation and to characterize the biocatalytic mechanism of the PTS in detail. For this purpose, soluble PTS was prepared using an optimized cultivation protocol and continuous downstream process with a purity of 98%. The PTS biotransformation was then optimized regarding buffer composition, pH‐value, and temperature for biotransformation as well as functional and kinetic properties to improve productivity. For the bioconversion of FPP, the highest enzyme activity was reached with the 2‐( N ‐morphlino)ethanesulfonic acid (MES) buffer containing 10% (v/v) glycerol and 10 mM MgCl ₂ at pH 6.4 and 34°C. The PTS showed an unusual substrate inhibition for sesquiterpene synthases indicating an intermediate sesquiterpene formed in the active center. Deuteration experiments were used to gain further insights into the biocatalytic mechanism described in literature. Thus it could be shown that a second substrate binding site must be responsible for substrate inhibition and that further protonation and deprotonation steps are involved in the reaction mechanism.