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Background Itaconic acid is a promising platform chemical for a bio-based polymer industry. Today, itaconic acid is biotechnologically produced with Aspergillus terreus at industrial scale from sugars. The production of fuels but also of chemicals from food substrates is a dilemma since future processes should rely on carbon sources which do not compete for food or feed. Therefore, the production of chemicals from alternative substrates such as acetate is desirable to develop novel value chains in the bioeconomy. Results In this study, Corynebacterium glutamicum ATCC 13032 was engineered to efficiently produce itaconic acid from the non-food substrate acetate. Therefore, we rewired the central carbon and nitrogen metabolism by inactivating the transcriptional regulator RamB, reducing the activity of isocitrate dehydrogenase, deletion of the gdh gene encoding glutamate dehydrogenase and overexpression of cis-aconitate decarboxylase (CAD) from A. terreus optimized for expression in C. glutamicum. The final strain C. glutamicum ΔramB Δgdh IDHR453C (pEKEx2-malEcadopt) produced 3.43 ± 0.59 g itaconic acid L−1 with a product yield of 81 ± 9 mmol mol−1 during small-scale cultivations in nitrogen-limited minimal medium containing acetate as sole carbon and energy source. Lowering the cultivation temperature from 30 °C to 25 °C improved CAD activity and further increased the titer and product yield to 5.01 ± 0.67 g L−1 and 116 ± 15 mmol mol−1, respectively. The latter corresponds to 35% of the theoretical maximum and so far represents the highest product yield for acetate-based itaconic acid production. Further, the optimized strain C. glutamicum ΔramB Δgdh IDHR453C (pEKEx2-malEcadopt), produced 3.38 ± 0.28 g itaconic acid L−1 at 25 °C from an acetate-containing aqueous side-stream of fast pyrolysis. Conclusion As shown in this study, acetate represents a suitable non-food carbon source for itaconic acid production with C. glutamicum. Tailoring the central carbon and nitrogen metabolism enabled the efficient production of itaconic acid from acetate and therefore this study offers useful design principles to genetically engineer C. glutamicum for other products from acetate.

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Abstract3D‐printing increased in significance for biotechnological research as new applications like lab‐on‐a‐chip systems, cell culture devices or 3D‐printed foods were uncovered. Besides mammalian cell culture, only few of those applications focus on the cultivation of microorganisms and none of these make use of the advantages of perfusion systems. One example for applying 3D‐printing for bioreactor development is the microbial utilization of alternative substrates derived from lignocellulose, where dilute carbon concentrations and harmful substances present a major challenge. Furthermore, quickly manufactured and affordable 3D‐printed bioreactors can accelerate early development phases through parallelization. In this work, a novel perfusion bioreactor system consisting of parts manufactured by fused filament fabrication (FFF) is presented and evaluated. Hydrophilic membranes are used for cell retention to allow the application of dilute substrates. Oxygen supply is provided by membrane diffusion via hydrophobic polytetrafluoroethylene membranes. An exemplary cultivation of Corynebacterium glutamicum ATCC 13032 supports the theoretical design by achieving competitive biomass concentrations of 18.4 g L−1 after 52 h. As a proof‐of‐concept for cultivation of microorganisms in perfusion mode, the described bioreactor system has application potential for bioconversion of multi‐component substrate‐streams in a lignocellulose‐based bioeconomy, for in‐situ product removal or design considerations of future applications for tissue cultures. Furthermore, this work provides a template‐based toolbox with instructions for creating reference systems in different application scenarios or tailor‐made bioreactor systems.

JavaScript (JS) is one of the most popular programming languages, and widely used for web apps, mobile apps, desktop clients, and even backend development. Due to its dynamic and flexible nature, however, JS applications often have a reputation for poor software quality. While the type-safe superset TypeScript (TS) offers features to address these prejudices, there is currently insufficient empirical evidence to broadly support the claim that TS applications exhibit better software quality than JS applications.We therefore conducted a repository mining study based on 604 GitHub projects (299 for JS, 305 for TS) with over 16M LoC. Using SonarQube and the GitHub API, we collected and analyzed four facets of software quality: a) code quality (# of code smells per LoC), b) code understandability (cognitive complexity per LoC), c) bug proneness (bug fix commit ratio), and d) bug resolution time (mean time a bug issue is open). For TS, we also collected how frequently the type-safety ignoring any type was used per project via ESLint.The analysis indicates that TS applications exhibit significantly better code quality and understandability than JS applications. Contrary to expectations, however, bug proneness and bug resolution time of our TS sample were not significantly lower than for JS: the mean bug fix commit ratio of TS projects was more than 60% larger (0.126 vs. 0.206), and TS projects needed on average more than an additional day to fix bugs (31.86 vs. 33.04 days). Furthermore, reducing the usage of the any type in TS apps appears to be beneficial: its frequency was significantly correlated with all metrics except bug proneness, even though the correlations were of small strengths (Spearman's rho between 0.17 and 0.26).Our results indicate that the perceived positive influence of Type-Script for avoiding bugs in comparison to JavaScript may be more complicated than assumed. While using TS seems to have benefits, it does not automatically lead to less and easier to fix bugs. However, more research is needed in this area, especially concerning the potential influence of project complexity and developer experience.