Opening up the ‘black box’
When Jack Pronk pulled an all-nighter one January evening back in 1998, waiting for approximately 6,500 spreadsheets to drop into his inbox, he could scarcely have imagined where it would all lead.
These were not just any spreadsheets. They contained the complete genetic sequence for all commonly known Baker’s yeasts. Instead of having to second-guess the behavior and composition of these most mysterious of single-cell fungi, he would finally know. “We were finally able to open up this ‘black box’ and look inside,” he recalls.
What Jack didn’t know was that it would set in motion a chain of events that represent one of the defining scientific achievements of our time.
Biofuels made from the unwanted and unused parts of plants - and produced through the successful fermentation of their sugars into ethanol…via the catalyst of yeast. Today, corn starch-based ethanol is being manufactured, sold and used as biofuel – in everyday cars – in the United States. Through the POET-Liberty project cellulosic ethanol will be added to this biofuel portfolio. The dream is that one day advanced biofuels will replace petroleum in cars altogether with incalculable benefits to the planet.
But like all great science, this achievement hasn’t come without its…roadblocks. “While we could ferment regular starch-based sugars into ethanol pretty easily using different yeasts, the real challenge we faced was finding a way to ferment the more complex cellulosic sugars that could deliver us the most efficient and waste-free process,” says Jack, a long-standing professor at the Delft Technical University in the Netherlands.
Specifically, Jack and his team began to focus their efforts on the so-called C5 sugars (those made of five carbon atoms); and in particular a sugar called xylose found in the woody, leafy - and thus inedible - parts of plants. “This was the ideal solution for producing a truly sustainable fuel - because the cellulosic part of the plants are inedible and thus not part of the food chain,” he explains.
The only problem was that the yeasts being used to ferment this particular sugar were simply not working efficiently enough.
The solution came from an unexpected (but not uncommon) scientific direction: The rumour mill. “We heard about some people in Nijmegen who had found a particular gene in a particular fungus…and we simply followed up on the lead. There was an element of serendipity to it all!”
Once identified, the gene was put into the yeast and eventually it removed the bottleneck. “It was a complex task and involved all kinds of targeted engineering in the laboratory where we effectively feeding the yeast these complex sugars to produce ethanol,” he says. “It was a lot of people working very hard at a time when biofuels were not on the scientific agenda in the way they are now.”
It very nearly never happened at all. When on the verge of taking his first ‘proper’ job as an assistant professor at Delft back in 1991, Jack received his call-up papers for Dutch Military Service. “I guess in the end the authorities thought I’d be more useful playing around with yeast than with a rifle in my hand,” he laughs.
It’s safe to say they were correct.