Turning straw to gold: How Ustilago maydis converts corn stover to high quality oil

Kira Müntjes1,2, Magnus Philipp1,2, Lesley Plücker1,2, Stefan Robertz2,4, Paul Richter2,3, Markus Pauly2,4,Marcel Mann2,3, Michael Feldbrügge1,2, Kerstin Schipper1,2

1 Institute for Microbiology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany

2 Bioeconomy Science Center (BioSC), c/o Forschungszentrum Jülich, 52425 Jülich, Germany

3 Aachener Verfahrenstechnik - Biochemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany

4 Institute for Plant Cell Biology and Biotechnology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany

The development of a bioeconomy is an important contribution to the UN"s Sustainable Development Goals Agenda 2030, that has been extensively promoted in recent years. In the framework of the BioSC, the NextVegOil project focuses on the production of a microbial palm oil substitute from the agricultural waste stream corn stover. Although plant oils like palm oil are a renewable material, the cultivation requires large deforested areas. In the case of palm oil, the CO2 emissions caused through deforestation of the rain forest as well as its worldwide transport are critical. Here we use the fungal chassis Ustilago maydis to produce a microbial oil that closely resembles the composition of palm oil. Currently, genetic engineering to tailor the fatty acid profile to further adapt the oil composition and to further increase the oil yields is conducted. In addition, a fluorescent reporter for online monitoring of oil accumulation was established. As a maize plant pathogen, U. maydis naturally possesses a set of carbohydrate-active enzymes that theoretically enables it to utilize complex substrates. By deregulating intrinsic enzymes and complementing the repertoire with heterologous hydrolytic enzymes we aim to further increase the utilization of the waste stream corn stover as sole carbon source for oil production.

In general, the biovalorization of corn stover on the one hand and the immense possible applications for microbial oil due to the huge marked volume of palm oil -containing products in the food industry on the other hand, underline the enormous potential of this product.