Sequential C1 fermentation - Converting CO2 into L-glutamate, 3-hydroxypropionate or mevalonate using Acetobacterium woodii and Corynebacterium glutamicum

We here apply sequential microbial bioprocesses by combining the acetate-producing features of Acetobacterium woodii from C1 substrates and the ability of Corynebacterium glutamicum to grow and to form value-added products from acetate. In a first fermentation, we demonstrate production of up to 400 mM bio-acetate with A. woodii from either CO₂ plus H₂ or from methanol under anaerobic conditions. In a subsequent cultivation, we employed C. glutamicum to convert the acetogen-derived bio-acetate into the amino acid L-glutamate (up to 13.1 mM = 1.93 g L⁻¹), or the heterologous products 3-hydroxypropionate (up to 40.8 mM = 3.68 g L⁻¹) and mevalonate (up to 11.3 mM = 1.67 g L⁻¹). The sequential fermentation platform presented here thus allows efficient biosynthesis of C3, C5, and C6 products starting from low cost and readily available C1 substrates and demonstrates the potential of the approach to convert C1 compounds into biologically produced higher-value products.