Polysialic acid (polySia), consisting of α-(2,8)-linked N-acetylneuraminic acid monomers plays a crucial role in many biological processes. This study presents a novel process for the production of endogenous polySia using Escherichia coli K1 in a disposable bag reactor with wave-induced mixing.Disposable bag reactors provide easy and fast production in terms of regulatory requirements as GMP, flexibility and can easily be adjusted to larger production capacities not only by scale up but also by parallelization. Due to the poor oxygen transfer rate compared to a stirred tank reactor (STR), pure oxygen was added during the cultivation to avoid oxygen limitation. During the exponential growth phase the growth rate was 0.61 h -1 . Investigation of stress-related product release from the cell surface showed no significant differences between the disposable bag reactor with wave-induced mixing and the STR. After batch cultivation a cell dry weight (CDW) of 6.8 g L -1 and a polySia concentration of www.els-journal.com Page 2 Engineering in Life SciencesThis article is protected by copyright. All rights reserved.

Modern bioprocess monitoring demands sensors that provide on-line information about the process state. In particular, sensors for monitoring bioprocesses carried out in single-use bioreactors are needed because disposable systems are becoming increasingly important for biotechnological applications. Requirements for the sensors used in these single-use bioreactors are different than those used in classical reusable bioreactors. For example, long lifetime or resistance to steam and cleaning procedures are less crucial factors, while a requirement of sensors for disposable bioreactors is a cost that is reasonable on a per-use basis. Here, we present an overview of current and emerging sensors for single-use bioreactors, organized by the type of interface of the sensor systems to the bioreactor. A major focus is on non-invasive, in-situ sensors that are based on electromagnetic, semiconducting, optical, or ultrasonic measurements. In addition, new technologies like radio-frequency identification sensors or free-floating sensor spheres are presented. Notably, at this time there is no standard interface between single-use bioreactors and the sensors discussed here.In the future, manufacturers should address this shortcoming to promote single-use bioprocess monitoring and control.

Yet already developed in the 1980s, the rise of 3D printing technology did not start until the beginning of this millennium as important patents expired, which opened the technology to a whole new group of potential users. One of the first who used this manufacturing tool in biotechnology was Lücking et al. in 2012, demonstrating potential uses . This study shows applications of custom‐built 3D‐printed parts for biotechnological experiments. It gives an overview about the objects' computer‐aided design (CAD) followed by its manufacturing process and basic studies on the used printing material in terms of biocompatibility and manageability. Using the stereolithographic (SLA) 3D‐printing technology, a customizable shake flask lid was developed, which was successfully used to perform a bacterial fed‐batch shake flask cultivation. The lid provides Luer connectors and tube adapters, allowing both sampling and feeding without interrupting the process. In addition, the digital blueprint the lid is based on, is designed for a modular use and can be modified to fit specific needs. All connectors can be changed and substituted in this CAD software‐based file. Hence, the lid can be used for other applications, as well. The used printing material was tested for biocompatibility and showed no toxic effects neither on mammalian, nor on bacteria cells. Furthermore an SDS‐PAGE‐comb was drawn and printed and its usability evaluated to demonstrate the usefulness of 3D printing for everyday labware. The used manufacturing technique for the comb (multi jet printing, MJP) generates highly smooth surfaces, allowing this application.

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