Future fuels will come in orange flavour

But researchers have to teach yeast to make it

Thursday 5 June 2014

Tim Brennan. Credit: AIBN

Tim Brennan. Credit: AIBN

Queensland researchers are persuading baker’s yeast to produce orange-flavoured renewable jet fuel from sugar.

Mr Timothy Brennan and his colleagues at the University of Queensland’s Australian Institute for Bioengineering and Nanotechnology have helped genetically-engineered yeast to evolve to make an oil called limonene, which is found naturally in lemons and oranges, and also happens to be an efficient jet fuel.

They’ve worked out how to get the yeast to make more oil without killing itself in the process.

It’s an important step in scaling up biofuel production so that it can become a serious alternative to traditional fossil fuels.

“When you open an orange, what you’re smelling is limonene – it’s a hydrocarbon that has excellent jet-fuel properties and recently outperformed traditional jet fuel in a model aircraft,” says Tim, the Queensland winner of Famelab Australia.

“We can take genes from oranges or lemons and assemble them in yeast to turn them into tiny limonene factories, which eat sugar and spit out orange-flavoured jet fuels,” he says.

While there are plenty of researchers already producing small amounts of yeast-derived biofuels around the world, one common limitation is the fact that production volumes are limited by the toxicity of the fuel. Tim and his colleagues have made two important steps forward.

The major stumbling block is that too much limonene is toxic to yeast cells, and this limits how much fuel the yeast cells can produce before it kills them.

“When you buy household cleaning products that smell like lemons or oranges, those flavour compounds aren’t just there to smell nice – they actually help kill bugs, and they kill yeast too,” Tim explains.

But Tim and his colleagues have worked out how to help the yeast survive the toxic conditions to produce greater volumes of the fuel.

They’ve redesigned the bioreactor so the fuel is removed immediately after being produced by the yeast. This has allowed the same yeast to tolerate up to 700 times more fuel than it would in a traditional bioreactor.

And they’re also altering the genes of the yeast to help it withstand higher levels of limonene.

“By changing only a single gene, I can improve the cells’ resistance to the fuel, so it can stand to produce more of it. But finding that gene wasn’t easy – I had to use biology’s oldest tool, adaptive evolution, to help me get there,” says Tim.

“I couldn’t wait for the yeast cells to evolve naturally on their own, so I sped up evolution in the lab. Each day I’d challenge them with a little more limonene than they had the day before. This constant environmental pressure ensured that only the fittest cells survived each day. Two months later I isolated a yeast strain that was much more resistant than the one I started with.”

Tim has just completed his PhD with The University of Queensland’s Australian Institute for Bioengineering and Nanotechnology (AIBN).

He’s part of a team working with Boeing and Virgin to come up with an alternative to petroleum-based fuels.

FameLab is a global science communication competition for early career scientists. Tim was the winner of the Queensland state competition, and was runner-up at the national final in May.

Media contacts:

Tim Brennan, AIBN UQ, t.brennan3@uq.edu.au, 0432 798 855
Niall Byrne, Science in Public, niall@scienceinpublic.com.au, 0417 131 977
Laura Boland, Science in Public, laura@scienceinpublic.com.au, 0408 166 426, (03) 9398 1416
Ruth Neale, AIBN media enquiries, r.neale1@uq.edu.au, (07) 3346 3965


Tim Brennan

Mr Timothy Brennan is a biochemical engineer and has recently completed his PhD with the AIBN at the University of Queensland. His PhD project is focussed on engineering tolerant yeast strains for the production of jet fuels, as part of the Queensland Sustainable Aviation Fuel Initiative (QSAFI).

Originally from California, Tim completed a Bachelor of Science (B.S.) in Chemical Engineering at the University of California, Berkeley, and following this, worked at the U.S. Department of Energy’s Joint BioEnergy Institute to develop novel technologies towards the efficient breakdown of biomass for biofuel production.

Tim also had research stints at Genentech and MIT where he helped build genetic tools to study malaria.

About AIBN

The University of Queensland’s Australian Institute for Bioengineering and Nanotechnology (AIBN) is an integrated multi-disciplinary research institute bringing together the skills of researchers working at the intersection of biology, chemistry, engineering and computer modelling.

The institute has more than 450 researchers housed in a $AU75 million state-of-the-art building complimented by an extensive suite of facilities.

This critical mass of researchers is working to develop new products and processes to impact human health, the environment, and the development of sustainable renewable energy.

AIBN goes beyond basic research to promote and develop the growth of innovative industries, which will benefit the Queensland and Australian economies.



Tim is part of Lars Nielsen group at AIBN. This work was funded by the Queensland government (National and International Research Alliances Program).

To find out more about QSAFI and its partners, please visit www.aibn.uq.edu.au/qsafi


logo - in associationIn 2014, the British Council and Fresh Science have joined forces to bring FameLab to Australia.

FameLab Australia will offer specialist science media training and, ultimately, the chance for early-career researchers to pitch their research at the FameLab International Grand Final in the UK at The Times Cheltenham Science Festival from 3 to 5 June 2014.

FameLab is an international communication competition for scientists, including engineers and mathematicians. Designed to inspire and motivate young researchers to actively engage with the public and with potential stakeholders, FameLab is all about finding the best new voices of science and engineering across the world.

Founded in 2005 by The Times Cheltenham Science Festival, FameLab, working in partnership with the British Council, has already seen more than 5000 young scientists and engineers participate in over 23 different countries – from Hong Kong to South Africa, USA to Egypt.

Now, FameLab comes to Australia in a landmark collaboration with the British Council and Fresh Science – Australia’s very own science-communicating competition.

For more information about FameLab Australia, head to www.famelab.org.au

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