Biobricks of Microbial Natural Product Syntheses, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena, Germany.
3 papers in the library · 127 citations · publishing 2018-2025
Expressing multiple genes from a biosynthetic pathway in eukaryotic hosts is challenging because each gene typically requires its own regulatory elements. A new vector system overcomes this by arranging genes as a single polycistron, using a picornavirus-inspired 'stop-carry on' mechanism so that all genes are controlled by one promoter. A split fluorescent reporter gene enables easy selection of transformed colonies. The method successfully produced high yields of the mushroom alkaloid psilocybin by expressing the entire biosynthetic gene cluster in the mould Aspergillus nidulans.
By deleting genes involved in L-tryptophan catabolism, psilocybin production was increased fivefold in baker's yeast and tenfold in the filamentous fungus Aspergillus nidulans. Process optimization in A. nidulans batch cultures yielded a final psilocybin titre of 267 mg/L with a space-time-yield of 3.7 mg/L/h. The engineered strain demonstrates suitability as a production chassis for psilocybin and other tryptamine-derived pharmaceuticals.
A bioprocess using a genetically modified strain of the fungus Aspergillus nidulans produced 542 mg per liter of psilocybin from glucose in 68 hours. The filamentous culture broth was sensitive to oxygen availability and power input, which affected viscosity and mass transfer. Scaling up from shake flasks to a 7-liter stirred tank reactor based on specific power input, along with enhanced oxygen supply in a pressure reactor and nitrogen limitation addressed by adding ammonium sulfate, yielded a robust batch process. This biotechnological approach could supplement chemical synthesis for supplying psilocybin for pharmaceutical use and demonstrates pressurized bioprocessing to overcome oxygen limitations for shear-sensitive filamentous organisms.