Podcast Transcript

Plant Sugars Provide Petrol

We all know that the days of fossil fuels are limited, so researchers are trying to find alternative fuels.  Biofuels have risen in popularity in recent years – fermenting plant material to make ethanol is already being used to produce fuel in several countries around the world.  But ethanol is a long way, chemically speaking, from the petrol (or gasoline for our US listeners) and diesel that are currently used in car engines.

The problem is that plant sugars have lots of oxygen atoms in them, which aren’t found in fuels like gasoline.  Now scientists at the University of Wisconsin-Madison have developed a biofuel that is identical, at the molecular level, to gasoline.  

Writing in the journal Science, the researchers have found a technique for turning complex plant sugars, called lignocellulose, into molecules that can be “upgraded” to make petrol, diesel and airplane fuel.  They do this by turning the plant sugars into molecules with fewer oxygen atoms, which can then be converted into high octane gasoline.

To create the new fuels, the scientists add a solid catalyst to a solution of the plant sugars. After a reaction, an oil-like substance is produced, that can be skimmed off the top of the solution. In this oil are acids, alcohols, ketones and other molecules, which are the precursors to gasoline. They can then be used in further reactions to make gasoline.

This is a much more efficient way of using lignocellulose for biofuels than previous techniques – the oil created by the team retains around 90% of the energy content found in the original sugars. Although this technique is still at an experimental stage, it might be the key to solving the oil crisis in the future.

21st Sep 2008

Fungi are world's fastest fliers

Scientists have discovered the fastest fliers in nature and, somewhat surprisingly, they're fungi!

Ohio-based researcher Nicholas Money and his colleagues at Miami University made the discovery by using ultra-fast cameras capable of taking 250,000 frames per second.  Down the lens they were studying members of two fungal families - the ascomycetes and the zygomycetes - that do the essential but unsalubrious job of breaking down animal dung.  These fungi rely on their spores passing harmlessly through the guts of grazing animals so that they land, quite literally, in the remains of their lunch.  But animals generally avoid grazing in areas where another animal has defaecated, leaving fungi like these with a problem.  Their solution is to have evolved the mycological equivalent of a "super-soaker" squirt gun - they fire their spores from tiny fluid-filled fruiting bodies so that they land in patches of uncontaminated grass ready for the next browsing ruminant.  But although scientists realised that the fungal launchpad must be incredibly powerful, it was too fast and too small to surrender its secrets, at least until now.

Writing in this weeks PLoS ONE the team have successfully made fungal ballistic measurements of spore trajectories to reveal that these organisms are firing their microscopic projectiles, which measure just a fraction of a millimetre across, at speeds exceeding 25 metres per second and at rates corresponding to 180,000 times the acceleration due to gravity.  This is sufficient to propel the spores up to 2.5 metres away from the parent dung pile.

The team were also able to get a handle on how the organisms achieve their fungal feat.  A concentrated mixture of sugars, alcohols and other metabolites inside the fungus and its fruiting body pulls in water by osmosis, priming the gun at a pressure about four times that of the atmosphere.  At the right moment the structure ruptures and the pressure drives out the spores.  According to the researchers the images of these fungal ejaculations are so pretty that they've set them to music and plan to post them on YouTube!