Engineering bioreactor mass production of arbuscular mycorrhizal fungi for European farming

Microbial inoculants containing arbuscular mycorrhizal fungi (AMF) are powerful tools in increasing the sustainability of our food production systems. These soil fungi form a symbiotic association with almost all major agricultural crops, acquiring nutrients beyond the nutrient-depleted zone of the rhizosphere to meet plant nutrient requirements, resulting in increased biomass and yield. AMF-colonized plants also show greater tolerance to a/biotic stresses. The production of these inoculants has thus huge economic value. However, current AMF production relies largely on substrate-based cultivation systems with suitable host plants, which is space-demanding, hard to scale-up and prone to carrying unwanted contaminants. An alternative exists with the production of AMF in vitro in root organ cultures (ROC). This method also has some drawbacks. It is labor-intensive, costly, and produces comparatively fewer spores than in the greenhouse. Mass production of AMF at industrial scale is, however, done in ROC, but in countries where labor costs are well below EU salaries. This model is not viable in the EU which is characterized by high salaries and stringent regulations.The ambition of AMFactory is therefore to bridge the gap between the contaminant-free production of AMFs in ROC and their mass-production in bioreactors at low costs, making EU worldwide competitive on the market of AMF bioinoculants. This will be achieved by engineering host roots for enhanced lipid metabolism to fuel the spores (WP1), identify and optimize plant-AMF signaling compounds for optimal colonization (WP2) and enable their low-cost, large-scale biosynthesis via microbial cell factories (WP3). The combination of engineered roots and signaling molecules will be tested and validated using ROC and advanced microfluidics (WP4) and the most promising confirmed in a bioreactor (WP5) with the final objective to produce 108 spores per L in a period of 4 to 6 months, applicable for European farming.