Summary

Plants and their sustainable production are key elements of a functioning bioeconomy. Yield and quality of plants and thus of food, feed, and raw materials for diverse plant-based processes are significantly affected by plant pathogens worldwide. To counteract losses caused by biotic stresses, novel, environmentally friendly, and safe ways to facilitate sustainable agri- and horticulture are urgently required. Microbial secondary metabolites are a rich source of bioactive molecules that can be used as such or serve as chemical platform molecules for developing plant protection products with favourable characteristics. We found that low amounts of rhamnolipids (RLs) significantly protect plants against plant-parasitic nematodes (PPNs). After achieving the proof-of-principle, we strive to contribute to the implementation of this strategy in agriculture. In RhamBO we will thus carry out first field experiments to verify the applicability of RLs to protect the important cultivar sugar beet from plant pathogens and pests.

Since the production of RLs (being surfactants) leads to heavy foaming in aerated fermenters, we will here also establish a production procedure on a technical scale (100 L). Preliminary experiments suggest that overpressure applied to the fermenter impedes foaming enough to carry out fed-batch runs. With the expertise and equipment of CG NGP² Biorefinery we will here show the feasibility of this approach for the production of at least 100 g of RLs. This includes RL that are even not available commercially.