Bioreactors with off-gas analysis by mass spectrometry

• Subject Area: Microbiology, Virology and Immunology
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569502488

Investigating growth of microorganisms and their diverse physiology requires various cultivation methods. In particular, in order to investigate microbial whole-cell catalysis toward the production of industrially relevant platform chemicals and fuels; continuous cultivation with pH-control must be carried out in bioreactors, in addition to batch approaches. In our department, we focus e.g. on the conversion of algae or plant polymers to organic acids and gases (hydrogen, H2 and carbon dioxide, CO2) by fermenting microorganisms, as well as on the conversion of gases (H2/CO2) by acetogenic microorganisms under anoxic conditions. Respective experiments are supposed be carried out in a bioreactor system with four parallel mini-reactors that can be controlled independently of each other, enabling the simultaneous investigation of replicates or of different strains and species under identical conditions. To study acetogenesis and sugar utilization by thermophilic microorganisms, including Thermoanaerobacter kivui and Thermotoga maritima, the bioreactors shall be operated at high temperatures in the range of 60–80°C in continuous and batch mode. The possibility of pH control (and regulation) is necessary to prevent growth inhibition by acid accumulation, achieving higher optical densities with increased product turnover. Another research area of our group is the laboratory evolution of thermophilic microorganisms, toward their biotechnological use, but also in fundamental research, studying their adaptation mechanisms towards growth at lower temperatures. Lower growth temperatures initially result in reduced growth rates of thermophiles. Here, continuous long-term cultivation in turbidostat mode is envisioned, allowing a controlled supply of nutrients without the biomass being washed out of the cultivation vessel. Anoxic conditions with the desired gas atmosphere (N2, H2 / CO2) are created by controlled supply of one or more gases. To quantify the gas utilization or gas production, the concentrations of the gases H2, CO2, N2, CH4, and O2 in the outflow of all bioreactors will be measured continuously and in parallel using a coupled gas mass spectrometer (MS). The acquisition of a multiple bioreactor system with downstream gas mass spectrometry thus enables research of the physiology of a large number of aerobic and anaerobic microorganisms and their cultivation under different conditions (batch, continuous: chemostat, turbidostat; pH-controlled). It will be an advanced platform technology for basic and applied microbiological research at the Institute of Biological Sciences at the University of Rostock.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Bioreaktoren mit massenspektrometrischer Gasanalytik
• Instrumentation Group: 3520 Bakterien-Zuchtgeräte, Fermenter
• Applicant Institution: Universität Rostock
• Leader: Professor Dr. Mirko Basen