Metabolic modeling of Chlamydomonas reinhardtii: energy requirements for photoautotrophic growth and maintenance

In this study, a metabolic network describing the primary metabolism of Chlamydomonas reinhardtii was constructed. By performing chemostat experiments at different growth rates, energy parameters for maintenance and biomass formation were determined. The chemostats were run at low irradiances resulting in a high biomass yield on light of 1.25 g  mol−1. The ATP requirement for biomass formation from biopolymers (Kx) was determined to be 109 mmol g−1 (18.9 mol mol−1) and the maintenance requirement (mATP) was determined to be 2.85 mmol g−1 h−1. With these energy requirements included in the metabolic network, the network accurately describes the primary metabolism of C. reinhardtii and can be used for modeling of C. reinhardtii growth and metabolism. Simulations confirmed that cultivating microalgae at low growth rates is unfavorable because of the high maintenance requirements which result in low biomass yields. At high light supply rates, biomass yields will decrease due to light saturation effects. Thus, to optimize biomass yield on light energy in photobioreactors, an optimum between low and high light supply rates should be found. These simulations show that metabolic flux analysis can be used as a tool to gain insight into the metabolism of algae and ultimately can be used for the maximization of algal biomass and product yield

The PPILOW project: Innovations improving welfare in low input and organic pig and poultry farms

International audienceThe PPILOW project aims to co-construct innovations to improve Poultry and Pig Welfare in Low-input outdoor and Organic farming systems through a multi-actor approach. PPILOW implements a participatory approach for proposing and studying welfare-improvement levers. It will provide a combination of practical solutions that can be applied at a pan-European level with specific adjustments depending on citizen’s expectations and the target market. The multi-actor approach consists in involving end-users including farmers, breeding companies, feed producers, consumer associations, retailers, advisers, processors, and scientists in National Practitioner Groups (NPG) in six participating countries. PPILOW partners facilitate the groups by connecting NPG at European level, transferring scientific information, interacting with partners engaged in animal experiments, and co-creating innovations rising from NPG-specific demands. They co-build with PPILOW partners welfare self-assessment tools (development of the PIGLOW app for pigs and refinement of the EBENE® app for poultry), and innovative breeding, feeding, and rearing strategies and techniques to improve the welfare of animals. They co-design protocols, test innovations on farm, and disseminate the results. In turn, they receive insights on methods and scientific results, and inputs from other NPG reinforcing the value of the expected outcomes. Approaches focus on avoiding physical damage and the elimination of layer male chicks, on reducing boar taint of intact male pigs, promoting positive behaviours, animal health, and robustness through field studies with pigs and poultry. Multicriteria analyses of the most effective levers of welfare improvement will be performed to evaluate their economic, social, and environmental impacts based on the ‘One Welfare’ concept; economic and business models will also be developed. To ensure the rapid uptake of the project results by end-users, the close involvement of PPILOW’s NPG throughout the EU will ensure disseminationactivities and the facilitation of change. The PPILOW project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement N°816172. www.ppilow.eu