A new approach for the generation and high-throughput detection of hydrogen-overproducing bacteria

The great interest for hydrogen (H₂) as energy vector underlies research programs aimed to improving its sustainable biological production. During the process of biological nitrogen fixation (N₂ - 2NH₃) the enzyme nitrogenase generates a minimum of one molecule of H₂ per turnover. This work, funded by the European Research Council, reveals high potential for nitrogenase improvement as biocatalyst for H₂ production.

This work shows the development of a biotechnological tool for the detection of H₂-overproducing bacteria. This tool consists of a library of (10⁵-10⁶) random nitrogenase variants and a biological H₂ sensor, which is based on the sensing hydrogenase of Rhodobacter capsulatus and produces fluorescent signals that are proportional to the amount of H₂ produced by each variant. High-throughput selection by coupling this tool to FACS cytometry was achieved. The selection of a nitrogenase variant resulting in 1000% improvement in bacterial H₂ production is shown as proof of concept.