Microbial hydrogen: Multi-omics explains

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  • Published: Nov 15, 2015
  • Author: David Bradley
  • Channels: Chemometrics & Informatics
thumbnail image: Microbial hydrogen: Multi-omics explains

Profile cyanobacteria

Genome-scale transcript and protein profiling suggest a new hypothesis on the metabolic relationship between oxygenic photosynthesis and nitrogenase-mediated hydrogen production in the ubiquitous oceanic cyanobacterium (blue-green alga), Cyanothece 51142 pointing the way to a previously unknown source of hydrogen that could be renewable and sustainable. Graphic adapted from Scientific Reports/Nature Publishing Group, Bernstein et al

Genome-scale transcript and protein profiling suggest a new hypothesis on the metabolic relationship between oxygenic photosynthesis and nitrogenase-mediated hydrogen production in the ubiquitous oceanic cyanobacterium (blue-green alga), Cyanothece 51142 pointing the way to a previously unknown source of hydrogen that could be renewable and sustainable.

The hydrogen economy has been talked about a great deal over the last few years, the generation of hydrogen sustainably from water using solar or other renewable energy sources, often being the key step to its advent. However, there might be a biological answer to sourcing this simplest of fuel materials sustainably in the discovery that cyanobacteria not only carry out the well known photochemical sugar-production process of photosynthesis at the same time they use solar energy to molecular hydrogen.

Microbial hydrogen economics

"The ultimate goal here is to take energy from the sun, and water, and produce useable energy," explains microbiologist Alex Beliaev, one of two scientists at the Department of Energy's Pacific Northwest National Laboratory in Richland, Washington, USA, who led the research. "The more we know about the pathways involved in this process, the more likely we will be able to find a facile and economic way to produce renewable energy. The organisms that produce clean energy naturally provide a blueprint of sorts for how we might do this." The team offers details of their discovery in the journal Scientific Reports, explain how the cyanobacterium makes hydrogen by extracting the element from stored sugars synthesised earlier in its growth. However, the microbes can also split water using sunlight to generate hydrogen.

Cyanobacteria and other organisms made modern life on Earth possible by generating the bulk of the in our atmosphere starting some 2.3 billion years ago. These same organisms also fix nitrogen from the air, making it available to plant life. These organisms are usually equipped with nitrogenase enzymes and it was known previously that nitrogenase can also generate small amounts of molecular hydrogen as a by-product of nitrogen fixation. In the absence of nitrogen, hydrogen production rises.

Bioreactors

With this in mind, the team set up Cyanothece 51142 in a bioreactor, limited the supply of nitrogen, and illuminated the vessel 24 hours a day for several weeks. The team obtained minute-by-minute profiling of the organism from an array of equipment as it processed water using light energy to generate hydrogen. The study was a "multi-omics experiment" analysing genomics, transcriptomics and proteomics of the organism's activity, as well as reaction kinetics. The team analysed data for 5303 genes and 1360 proteins at eight separate times. The organism generates hydrogen at a much higher rate than any other known natural system.

"This organism can make lots of hydrogen, very fast; it's a viable catalyst for hydrogen production," explains Hans Bernstein. "The enzyme that makes the hydrogen needs a huge amount of energy. The real question is, what funds the energy budget for this important enzyme and then, how can we design and control it to create renewable fuels and to advance biotechnology?" In earlier work, the team had raised questions as to the energy source, but they have now shown that photosynthesis and hydrogen production by nitrogenase work in a coordinated manner.

Related Links

Sci Rep 2015, online: "Multi-omic dynamics associate oxygenic photosynthesis with nitrogenase-mediated H2 production in Cyanothece sp. ATCC 51142"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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