Biology subjects

Kerzenmacher, S.

Publications and source records attributed to Kerzenmacher, S..

3 recordsLinked to original sources

bioRxiv2024

Resource-efficiency of cyanobacterium production on Mars: Assessment and paths forward

Space agencies and private companies strive for a permanent human presence on the Moon and ultimately on Mars. Bioprocesses have been advocated as key enablers due to their ability to transform locally available resources into added-value materials. However, the resource-efficiency and scaling of space biosystems remain poorly understood, hindering quantitative estimates of their potential performance. We leveraged extensive cultivation experiments, where a cyanobacterium (Anabaena sp. PCC 7938) was subject to conditions attainable on Mars, to develop a model that can estimate bioprocess productivity and resource-efficiency as a function of water, light, temperature, regolith minerals and perchlorates, and atmospheric carbon and nitrogen. We show that a breakeven can be reached within a few years. We discuss research lines to improve both resource efficiency and the accuracy of the model, thereby reducing the need for costly tests in space and eventually leading to a biotechnology-supported, sustained human presence on Mars. TEASERBioprocess modeling shows that cyanobacterium-based biotechnologies can be a sustainable basis for resource production on Mars.

microbiology↗

bioRxiv2021

Optimization of growth and electrosynthesis of PolyHydroxyAlcanoates by the thermophilic bacterium Kyrpidia spormannii

The electrosynthesis of valuable compounds by biofilms on electrodes is being intensively studied since few years. However, so far, the actual biofilms growing on cathodes produce mainly small and relatively inexpensive compounds such as acetate or ethanol. Recently, a novel Knallgas bacterium, Kyrpidia spormannii EA-1 has been described to grow on cathodes under thermophilic and microaerophilic conditions, producing significant amounts of PolyHydroxyAlkanoates (PHAs). These PHA are promising sustainable bioplastic polymers with the potential to replace petroleum-derived plastics in a variety of applications. However, the effect of culture conditions and electrode properties on the growth of K. spormannii EA-1 biofilms and PHA production is still unclear. In this study, we report on the optimization of growth and PHA production in liquid culture and on the cathode of a Microbial Electrosynthesis System. Optimization of the preculture allows to obtain high cell density of up to 8.5 Log10 cells{middle dot}ml-1 in 48h, decreasing the time necessary by a factor of 2.5. With respect to cathodic biofilm formation, this study was focused on the optimization of three main operating parameters, which are the applied cathode potential, buffer pH, and the oxygen concentration in the feed gas. Maximum biofilm formation and PHA production was observed at an applied potential of -844mV vs. SCE, pH 6.5, O2 saturation of 2.5%. The PHA concentration in the biofilm reached a maximum of {approx}26.8 g{middle dot}cm-2 after optimization, but at 2.9% the coulombic efficiency remains relatively low. We expect that further nutrient limitation will allow the accumulation of more PHA, based on a dense biofilm growth. In conclusion, these findings take microbial electrosynthesis of PHA a step forward towards practical implementation.

bioengineering↗

bioRxiv2021

High current production of Shewanella oneidensis with electrospun carbon nanofiber anodes is directly linked to biofilm formation

1We study the current production of Shewanella oneidensis MR-1 with electro-spun carbon fiber anode materials and analyze the effect of the anode morphology on the micro-, meso-and macroscale. The materials feature fiber diameters in the range between 108 nm and 623 nm, resulting in distinct macropore sizes and surface roughness factors. A maximum current density of (255{+/-} 71) {micro}A cm-2 was obtained with 286 nm fiber diameter material. Additionally, micro-and mesoporosity were introduced by CO2 and steam activation which did not improve the current production significantly. The current production is directly linked to the biofilm dry mass under anaerobic and micro-aerobic conditions. Our findings suggest that either the surface area or the pore size related to the fiber diameter determines the attractiveness of the anodes as habitat and there-fore biofilm formation and current production. Reanalysis of previous works supports these findings.

microbiology↗