Scientist Improve Biohydrogen Production in Enterobacter aerogenes

Enterobacter aerogenes is an anaerobe and is a widely studied strain due to its ability to use a variety of substrates, to produce hydrogen. However, the rate of hydrogen production has not been optimized. Zhejiang Sci-Tech University researcher Yan Wu evaluated strategies to improve hydrogen production in E. aerogenes, such as disruption of nuoCDE, and overexpression of NadE. This study also aims to clarify the effect of nuoCDE and NadE on hydrogen production.

NADH dehydrogenase activity was impaired by knocking out nuoCD or nuoCDE in E. aerogenes IAM1183 using the CRISPR-Cas9. The hydrogen yields from IAM1183-CD(∆nuoC/∆nuoD) and IAM1183-CDE (∆nuoC/∆nuoD/∆nuoE) increased significantly. The hydrogen produced via the NADH pathway also increased significantly in IAM1183-CDE, suggesting that nuoCDE plays an important role in regulating NADH concentration in E. aerogenes.

Meanwhile, overexpression of NadE (N) resulted in increased hydrogen yields of IAM1183/N, IAM1183-CD/N, and IAM1183-CDE/N, compared with the control IAM1183. The team then focused on IAM1183-CDE/N, which had the best hydrogen-producing traits, as a potential candidate for industry applications. Hydrogen production from IAM1183-CDE/N reached up to 1.95 times greater than that measured for the control IAM1183.

Knockout of nuoCD or nuoCDE and the overexpression of nadE in E. aerogenes resulted in a redistribution of metabolic flux and improved its hydrogen yield. This study also shows the success of CRISPR-Cas9 technology in editing genes in E. aerogenes.