Das Lehrgebiet publiziert im Journal Biotechnology and Bioengineering zum Thema: " Passively immobilized cyanobacteria Nostoc species BB 92.2 in a moving bed photobioreactor (MBPBR): design, cultivation and characterization".

The cyanobacterium Nostoc sp. BB 92.3. had shown antibacterial activity. A cultivation as biofilm, a self-forming matrix of cells and extracellular polymeric substances, increased the antibacterial effect. A new photobioreactor system was developed that allows a surface-associated cultivation of Nostoc sp. as biofilm. High-density polyethylene carriers operated as a moving bed were selected as surface for biomass immobilization. This system, well established in heterotrophic wastewater treatment, was for the first time used for phototrophic biofilms. The aim was a cultivation on a large scale without inhibiting growth while maximizing immobilization. Cultivation in a small photobioreactor (1.5 L) with different volumetric filling degrees of carriers (13.4-53.8 %) in a batch process achieved immobilization rates of 70-85 % and growth was similar to a no-carrier-control. In a larger photobioreactor (65-liter) essentially all of the biomass was immobilized on the carriers and the space-time yield of biomass (0.018 gcell dry weight L-1 day-1) was competitive compared to phototrophic biofilm cultivations from literature. The use of carriers increased the gas exchange in the reactor by a factor of 2.5-3, but doubled the mixing time. Enriched gassing with carbon dioxide resulted in a short-term increase in growth rate, but unexpectedly it also adversely changed the growth morphology.

J. Walther, N. Erdmann, M. Stoffel, K. Wastian, A. Schwarz, D. Strieth, K. Muffler, R. Ulber, Passively immobilized cyanobacteria Nostoc species BB 92.2 in a moving bed photobioreactor (MBPBR): design, cultivation and characterization (2022). Journal Biotechnology and Bioengineering, DOI: 10.1002/bit.28072