Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search


Otago researchers help clear up enduring mystery

Otago researchers discover how soils control atmospheric hydrogen

University of Otago researchers are helping to clear up an enduring mystery regarding the composition of the Earth’s atmosphere. They have discovered the microbial soil processes that help ensure that the explosive gas hydrogen remains at trace levels.

In recent decades it was found that around four-fifths of all hydrogen released into the air is rapidly removed through soil activity, but exactly what is recycling it, and how, has remained unclear.

Now, Otago scientists have shown that the soil bacterium Mycobacterium smegmatis uses two special enzymes that can efficiently scavenge hydrogen as fuel at very low concentrations. They also found the bacterium ramps up these enzymes’ activity when starved of its usual carbon-based energy sources.

The Department of Microbiology & Immunology researchers’ findings appear in the prestigious journal Proceedings of the National Academy of Sciences (PNAS). Their discovery has implications for improved understanding of global climate processes and for developing new catalysts for hydrogen fuel cells.

Study lead author and Otago PhD candidate Chris Greening says the findings emerge from a project led by Professor Greg Cook investigating why the mycobacteria family, which includes members causing TB and leprosy, have genes encoding hydrogenase enzymes. Hydrogenases are well-known for their roles in anaerobic bacteria, but this is the first comprehensive study of these enzymes in an organism that requires oxygen to combust their fuel sources.

“Hydrogen scavenging is just one example of the ingenuity of microorganisms. Bacterial metabolism is much more flexible than that of humans. While we rely on carbon sources such as sugars and amino acids, many bacteria can use gases (e.g. hydrogen, carbon monoxide) and even metals (e.g. iron, uranium) as fuel sources for growth and survival,” says Mr Greening.

It now appears that M. smegmatis and several other species of soil actinobacteria are demonstrating a metabolic flexibility that would provide a powerful advantage over other aerobic microbes in soil ecosystems, he says.

“High-affinity hydrogenases allow these bacteria to harness hydrogen to survive on when their standard carbon-based fuel sources are absent. While hydrogen is at low concentrations in the air, it is essentially a constant and unlimited resource. This means that bacteria scavenging this highly dependable fuel source would be especially competitive against other organisms in their volatile environments.”

On a global scale, this activity leads to soil actinobacteria serving as the main sink for atmospheric hydrogen. This in turn influences the concentrations of other gases in the atmosphere, including potent greenhouse gases such as methane and nitrous oxide, he says.

Mr Greening says that hydrogenases have additionally attracted interest from researchers working to make dependable, inexpensive hydrogen fuel cells a reality. “Developing a catalyst that mimics the high-affinity, oxygen-tolerant action of the hydrogenases in M. smegmatis would provide an enormous boost for this technology,” he says.

Originally from the UK, Mr Greening joined Professor Cook’s laboratory in November 2010 after completing a Bachelor’s and Master’s degree in Biochemistry at the University of Oxford. He will shortly complete his doctoral studies at Otago to take up a position researching drug targets for TB at CSIRO, Australia’s national science agency.

“I decided to come here to do my PhD under Professor Cook after attending a research presentation he gave at Oxford.” Having been awarded a first class degree at Oxford, Mr Greening pretty much had the choice of any world-leading institution to continue his studies. However, he says “Greg’s multifaceted science captured my imagination so strongly that I set my sights on Otago.”

The team’s project was supported by a Marsden Fund Grant awarded to Professor Cook and study co-author Dr Michael Berney. The other co-authors include Kiel Hards, who studied the hydrogenases during his BSc Honours year, and Professor Dr Ralf Conrad, director of the Max-Planck Institute for Terrestrial Microbiology in Marburg, Germany.

© Scoop Media

Business Headlines | Sci-Tech Headlines


Hourly Wage Gap Grows: Gender Pay Gap Still Fixed At Fourteen Percent

“The totally unchanged pay gap is a slap in the face for women, families and the economy,” says Coalition spokesperson, Angela McLeod. Even worse, Māori and Pacific women face an outrageous pay gap of 28% and 33% when compared with the pay packets of Pākehā men. More>>


Housing: English On Housing Affordability And The Economy

"Long lead times in the planning process tend to drive prices higher in the upswing of the housing cycle. And those lead times increase the risk that eight years later, when additional supply arrives, the demand shock that spurred the additional supply has reversed. The resulting excess supply could produce a price crash..." More>>


Sweet Health: Sugary Drinks Banned From Hospitals And Health Boards

All hospitals and DHBs are expected to kick sugary drinks out of their premises. University of Auckland researcher, Dr Gerhard Sundborn who also heads public health advocacy group “FIZZ”, says he welcomes the initiative. More>>


NASA: Evidence Of Liquid Water On Today's Mars

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. More>>


Bird Brains: Robins Can Just Be Generally Clever

Research from Victoria University of Wellington has revealed that birds may possess a ‘general intelligence’ similar to humans, with some individuals able to excel in multiple cognitive tests. More>>


Psa-V: Positive Result On Whangarei Kiwifruit Orchard

Kiwifruit Vine Health (KVH) has received a Psa-V positive test result on Hort16A and male vines on a kiwifruit orchard in Whangarei. This is the first confirmed case of Psa-V on an orchard in the Whangarei region. More>>

Regional Accents: Are Microbes The Key To Geographical Differences In Wine?

A new study of six of New Zealand’s major wine-growing regions has found that differences in flavour and aroma of wine from different areas may depend more on microbes than was previously thought. More>>


Science: AgResearch To Cut Science Staff In Areas Of 'Reduced Demand'

“We are therefore consulting with our staff from today on a proposal to reduce science staff in areas of shrinking demand. Combined with recruitment planned in areas of growing demand, this would mean a net reduction of 15 scientists and 41 technicians at AgResearch in the 2015/16 year." More>>


Get More From Scoop

Search Scoop  
Powered by Vodafone
NZ independent news