U.S. Department of Energy

Pacific Northwest National Laboratory

Bacteria Produces Biofuel to Protect Itself From Oxidative Stress

A chart depicting oxidative stress.

The Science                      

Hydrogen gas (H2) is a zero-emission alternative fuel that can be produced by microbes. One promising platform for H2production is the cyanobacteria Cyanothece51442. A new paper by researchers at the Pacific Northwest National Laboratory (PNNL) describes how Cyanothece 51142 initiates high levels of sustained H2synthesis to protect itself from oxidative stress brought on during photosynthesis. These results provide insight into the underlying dynamics that facilitate making Hthis way.

The Impact

H2-producing enzymes are widely regarded as highly sensitive to oxygen, yet Cyanothece51142 can perform oxygenic photosynthesis with H2as an atypical byproduct. It appears that this species uses enzyme-driven Hsynthesis to prevent oxidative stress. This is a previously unrecognized role for the H2-producing enzyme and is an exciting feature that may represent a strategy for utilizing this cyanobacterium for efficient and scalable H2production. 

Summary

Advancements in alternative fuel are essential to alleviating the energy demands of a growing world population. Hydrogen gas (H2) is one of these, a biofuel that can be produced by the cyanobacterium Cyanothece5114 (officially,Cyanothecesp. ATCC 51142). Protection from oxidative stress during the production of H2depends on a cyanobacterial dinitrogenase enzyme complex called NifHDK.

This previously unknown feature ofCyanothece51142 may represent a strategy to exploit cyanobacteria for efficient and scalable H2production. NifHDK apparently acts as an emergency electron valve to prevent the formation of harmful reactive oxygen species. It works in concert with other cell strategies for maintaining redox homeostasis, an atomic-level chemical state in which the electron loss (oxidation) and electron gain (reduction) imposed by environmental and metabolic processes are buffered in a way that prevents cell damage.

The PNNL researchers, led by scientists Natalie C. Sadler and Aaron T. Wright, used an in vivo chemoproteomic profiling approach to explore the protein thiol redox dynamics in Cyanothece51142 cells over time to capture these molecular events during environmentally stimulated H2production. Their results provide new insight into electron partitioning and regulatory mechanisms. The findings could be useful for advancing the microbial photolytic bioenergy technology behind making fuels like H2

Funding

DOE BER, Biofuels SFA and the Panomics Program.

Publications

N. Sadler et al., “Dinitrogenase driven Photobiological Hydrogen Production Combats Oxidative Stress in Cyanothecesp. ATCC 51142.” Applied and Environmental Microbiology. http://aem.asm.org/content/early/2016/10/10/AEM.02098-16.abstract

Related Links

http://www.nature.com/articles/srep16004

http://pubs.acs.org/doi/abs/10.1021/cb400769v

http://mbio.asm.org/content/3/4/e00197-12

Date: 
November 2015
| Pacific Northwest National Laboratory