Exploiting the potential of additive technologies for advanced micro-cultivation solutions for microalgae and plant cells

Due to their potential to produce a great variety of valuable products bioprocesses using plant cells and microalgae are of growing industrial interest. The cultivation of eukaryotic production systems is challenged by slow growth rates, uncontrolled formation of cell aggregates, adherence to surfaces, shear sensitivity due to their huge cell size and by maintaining the productivity. Because of the high complexity of the biological systems there is only limited knowledge about the physiological and kinetic dependencies on the cultivation conditions. Therefore, advanced micro-cultivation systems are necessary enabling a detailed investigation on the micro- (cellular-scale, e.g. viability, morphologyEL) and macro-scale (process-scale, e.g. product formation kinetics, substrate consumptionEL). Additive technologies have the potential to meet these complex biological requirements. This work describes the design of two micro-cultivation environments for suspended and immobilized microalgae and plant cells by additive technologies. First, a milliliter-scale (V = 15 mL) Flat-Panel-Airlift photobioreactor equipped with optical sensors for the real-time measurement of dry weight concentration, chlorophyll fluorescence, pH, dO2 and dCO2 is presented. As a second example, we present a method called Green Bioprinting which was derived from tissue engineering bioprinting approaches and describes the fabrication of three-dimensional hydrogel-based immobilization structures for microalgae, plant cells and even structural organized co-cultures of different cell types. It was shown that the hydrogel-environment provided excellent growth and viability conditions using Chlamydomonas reinhardtii and Ocimum basilicum. The Green Bioprinting technology enables the study of cell-cell interactions (e.g. symbiotic living organisms) or the design of three-dimensional immobilization structures to perform cascaded bioprocesses.