A fungus that can convert plant waste directly into diesel could allow us to generate biofuel without sacrificing food production.
The fungus was discovered in leaves of the ulmo tree (Eucryphia cordifolia) which grows in Patagonia. It makes the diesel as a vapour, much easier than liquid fuel to extract, purify and store.
鈥淭here鈥檚 no other known organism on the planet that does this,鈥� says of Montana State University in Bozeman, US, who discovered the fungus. 鈥淚 would guess the gas mixture itself would be adequate to run an engine.鈥�
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Strobel identified the diesel vapours in Gliocladium roseum, an endophyte 鈥� a fungus that lives in between plant cells. He established that the fungus produces the vapours to kill off other fungi.
Analysis of the vapour showed it to be rich in hydrocarbons found in diesel, such as octane. Additionally, he identified low-molecular-weight alcohols and esters that together burn much more cleanly and efficiently than ordinary diesel. The high content of pure hydrocarbons means that it burns better than bioethanol produced from sugar cane, for example, which contains oxygen atoms and so stores less energy than hydrocarbons.
Cellulose bonus
The other bonus is that the fungus can grow on cellulose, which contains huge amounts of hydrocarbon but is notoriously difficult to break down.
鈥淚t鈥檚 the most abundant organic compound produced on earth, but most of it goes to waste,鈥� says Strobel. By fermenting the fungus on cellulose, it should be possible to generate huge quantities of the diesel vapour 鈥渞eady-for-use鈥�.
More experiments are needed to demonstrate that the idea is practical. 鈥淲e鈥檒l do some scale-up and fermentation, then get enough to run a little engine,鈥� says Strobel. 鈥淚f we can do that, we are in business.鈥�
Strobel says that the fungus is doubly valuable because it contains unique genes which make enzymes to break down cellulose into diesel vapour. These could theoretically become more active when spliced into other organisms, allowing diesel to be produced more efficiently.
One other extraordinary possibility following on from the discovery is that fuel oil may not be generated solely by subjecting organic matter to pressure and heat.
鈥淚t鈥檚 always been assumed that all oil is made through these geophysical processes,鈥� says Strobel. 鈥淏ut maybe there are microbial processes that make oil too, so maybe we could make our own crude oil through a process that鈥檚 totally green.鈥�
Journal reference: Microbiology, DOI:
