Trichoderma atroviride IMI 206040 synthesizes the coconut lactone 6-pentyl-α-pyrone (6-PAP) de novo and Aspergillus niger DSM 821 produces the rose-like flavour compound 2-phenylethanol (2-PE) from the precursor l-phenylalanine. Here, microparticles of different chemical composition and nominal particle diameter in the range 5-250 µm were added to shake-flask cultures of both fungi to investigate the particles' effect on product formation. Maximum 2-PE concentration increased by a factor of 1.3 to 1430 mg/l with the addition of 2% w/v talc (40 µm diameter). Maximum 6-PAP concentration increased by a factor of 2 to 40 mg/l with the addition of 2% w/v iron (II, III) oxide. The influence of ions leaching out of the particles was investigated by cultivating the fungi in leached particle medium. For the first time, the positive effect of the microparticle-enhanced cultivation (MPEC) technique on the microbial production of volatile metabolites, here flavour compounds from submerged fungal cultures, is demonstrated. The effect is strain- and particle-specific.

Geopolymer (GP) inorganic binders have a superior acid resistance compared to conventional cement (e.g., Portland cement, PC) binders, have better microbial compatibility, and are suitable for introducing electrically conductive additives to improve electron and ion transfer properties. In this study, GP–graphite (GPG) composites and PC–graphite (PCG) composites with a graphite content of 1–10 vol % were prepared and characterized. The electrical conductivity percolation threshold of the GPG and PCG composites was around 7 and 8 vol %, respectively. GPG and PCG composites with a graphite content of 8 to 10 vol % were selected as anode electrodes for the electrochemical analysis in two-chamber polarized microbial fuel cells (MFCs). Graphite electrodes were used as the positive control reference material. Geobacter sulfurreducens was used as a biofilm-forming and electroactive model organism for MFC experiments. Compared to the conventional graphite anodes, the anode-respiring biofilms resulted in equal current production on GPG composite anodes, whereas the PCG composites showed a very poor performance. The largest mean value of the measured current densities of a GPG composite used as anodes in MFCs was 380.4 μA cm–2 with a standard deviation of 129.5 μA cm–2. Overall, the best results were obtained with electrodes having a relatively low Ohmic resistance, that is, GPG composites and graphite. The very first approach employing sustainable GPs as a low-cost electrode binder material in an MFC showed promising results with the potential to greatly reduce the production costs of MFCs, which would also increase the feasibility of MFC large-scale applications.

A composite of polypyrrole (PPy) and polystyrenesulfonate (PSS) exchanges cations and is a promising material for the technical application of water softening. The ion exchange properties of electrochemically prepared PPy(PSS) are studied by investigating the polymer using an electrochemical quartz crystal microbalance (EQCM) and by analysing the solution surrounding the polymer by atomic absorption spectroscopy (AAS). The exchange of cations by PPy(PSS) is found to be caused by three driving forces: electrochemical oxidation/reduction of PPy; chemical oxidation of PPy by dissolved oxygen; gradients of cation concentration between polymer and solution. The ion selectivity of PPy(PSS) is investigated and ion exchange isotherms for the binary systems Ca 2+ /Na + and Ca 2+ / Mg 2+ are determined.

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To achieve a successful transition to a sustainable carbon and energy management, it is essential to both reduce CO2 emissions and develop new technologies that utilize CO2 as a starting substrate. In this study, we demonstrate for the first‐time the functionalization of geopolymer binder (GP) with Sn for electrochemical CO2 reduction (eCO2RR) to formate. By substituting cement with Sn‐GP, we have merged CO2 utilisation and emission reduction. Using a simple mixing procedure, we were able to obtain a pourable mortar containing 5 vol. % Sn‐powder. After hardening, the Sn‐GP electrodes were characterized for their mechanical and CO2 electrolysis performance. In 10 h electrolyses, formate concentrations were as high as 22.7±0.9 mmol L−1 with a corresponding current efficiency of 14.0±0.5 % at a current density of 20 mA cm−2. Our study demonstrates the successful design of GP‐electrodes as a new class of hybrid materials that connect eCO2RR and construction materials.