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Modelling higher plant growth is of strategic interest for modern agriculture as well as for the development of bioregenerative life support systems for space applications, where crop growth is expected to play an essential role. The capability of constraint-based metabolic models to cope the diel dynamics of plants growth is integrated into a multilevel modelling approach including mass and energy transfer and enzyme kinetics. Lactuca sativa is used as an exemplary crop to validate, with experimental data, the approach presented as well as to design a novel model-based predictive control strategy embedding metabolic information. The proposed modelling strategy predicts with high accuracy the dynamics of gas exchange and the distribution of fluxes in the metabolic network whereas the control architecture presented can be useful to manage higher plants chambers and open new ways of merging metabolome and control algorithms.

One of the main challenges in the development of bioprocesses based on cell transient expression is the commonly reported reduction of cell specific productivity at increasing cell densities. This is generally known as the cell density effect (CDE). Many efforts have been devoted to understanding the cell metabolic implications to this phenomenon in an attempt to design operational strategies to overcome it. A comprehensive analysis of the main studies regarding the CDE is provided in this work to better define the elements comprising its cause and impact. Then, examples of methodologies and approaches employed to achieve successful transient expression at high cell densities (HCD) are thoroughly reviewed. A critical assessment of the limitations of the reported studies in the understanding of the CDE is presented, covering the leading hypothesis of the molecular implications. The overall analysis of previous work on CDE may offer useful insights for further research into manufacturing of biologics.

Phase separation in multiphase flows in space systems is a challenging task due to the absence of buoyancy. Several phase separation approaches have been presented in the last years given the important role that systems containing multiphase flows will play in future space missions. We present a review of these techniques and a trade-off analysis for their application in life support systems and, in particular, in the MELiSSA (Micro Ecological Life Support System Alternative) photosynthesis bioreactor. The candidate approaches are evaluated, both quantitatively and qualitatively, according to the defined requirements and criteria. The outcome of the trade-off analysis shows passive static and acoustic techniques as the most recommended methods to carry out phase separation in the considered bioreactor., Peer Reviewed, Postprint (published version)

MELiSSA (Micro Ecological Life Support System Alternative) is developing bioregenerative Life Support technologies for long-term Space missions. The MELiSSA concept is conceived as a loop with several compartments, each one performing a specific function, providing all together edible material production, atmosphere regeneration and water recovery with a concomitant use of wastes, i.e., CO and organic wastes. Each one of the compartments is colonized with specific bacteria or higher plants depending on its specific function. The MELiSSA Pilot Plant is a facility designed for the terrestrial demonstration of this concept, hosting laboratory rats as a crew mock-up mimicking the respiration of humans. Currently, the MELiSSA Pilot Plant focus on the integration of three compartments: Compartment 3 (nitrifying packed-bed bioreactor based on the co-culture of immobilized Nitrosomonas europaea and Nitrobacter winogradsky), compartment 4a (an air-lift photobioreactor for the culture of the edible cyanobacteria Limnospira indica with concomitant oxygen production) and Compartment 5 (an animal isolator with rats as mock-up crew). The output from these tests shows a high robustness and reliability and the performance of oxygen producing and oxygen consuming compartments is successfully demonstrated under transitory and steady-state conditions. This contribution reports on the current state of development of the MELiSSA Pilot Plant Facility and the most recent results of the integration work.