Physiologic manipulation of microalgae-bacteria consortia: chances and limitations

Microalgae-bacteria consortia (MBC) have the potential to contribute to the cost-efficient harvesting of biomass while simultaneously remediating polluted water bodies in chemostatic photobioreactors. To further enhance the performance of bioreactors, it is imperative to understand how (a)biotic physiological parameters affect floc morphology, sinking properties and metagenomic species composition. This study investigates the impact of five manipulated environmental parameters such as antibiotic treatment, light intensity, pH value, salinity and temperature. The results demonstrate that MBC cultures show a robust response to diverse environments, most likely due to an increased protection within the floc formation. However, extreme antibiotic, pH value and temperature conditions affected the sinking properties and trigger distinctive alterations in the biotic community. Consequently, these conditions should be ideally avoided in running bioreactor systems. The findings offer novel insights into the dynamics of meta-communities, such as MBC cultures, in terms of their physiological cultivation conditions. Moreover, the presented methods enable efficient monitoring of MBC cultures in photobioreactors, while the obtained results offer strategies for further optimization of their biotechnological application.