Scale-Up of Dark Fermentative Biohydrogen Production by Artificial Microbial Co-Cultures

As a renewable energy carrier, dark fermentative biohydrogen (H2) represents a promising future alternative to fossil fuels. Recently, the limited H2 yield of 4 moles of H2 per mole glucose, the so-called “Thauer limit”, was surpassed by a defined artificial consortium. In this article, we demonstrate the upscaling of this drawing board design, from serum bottles to laboratory scale bioreactors. Our results illustrate that this designed microbial co-culture can be successfully implemented in batch mode, with maximum H2 yields of 6.18 and 4.45 mol mol−1 substrate. Furthermore, we report volumetric H2 productivities of 105.6 and 80.8 mmol H2 L−1 h−1. These rates are higher than for any other dark fermentative H2 production system using a synthetic microbial co-culture applied in batch mode on a defined medium. Our study is an important step forward for the application of artificial microbial consortia in future biotechnology and energy production systems.