Self-destructing bacteria could make for cheaper biofuels

US researchers believe they might have found a way to make biofuels cheaper and easier to produce … by genetically programming microbes to self-destruct after photosynthesis, thus eliminating the difficult task of separating the bacteria from the oil inside.

“The real costs involved in any biofuel production are harvesting the goodies and turning them into fuel,” said Roy Curtiss, director of the Biodesign Institute’s Centre for Infectious Diseases and Vaccinology and professor in the School of Life Sciences at Arizona State University (ASU). “This whole system that we have developed is a means to a green recovery of materials not requiring energy dependent physical or chemical processes.”

Curtiss is part of a large, multidisciplinary ASU team working to optimise cyanobacteria — the photosynthetic microbes responsible for pond scum — as a source of renewable biofuels. These microbes are easy to genetically manipulate and have a potentially higher yield than any plant crops currently being used as transportation fuels.

Until now, however, harvesting the fats from the microbes after photosynthesis has required many cost-intensive processing steps. Cyanobacteria have a multi-layer, burrito-like, protective set of outer membranes that help the bacteria thrive in even harsh surroundings.

To get the cyanobacteria to more easily release their precious, high-fat cargo, Curtiss and postdoctoral researcher Xinyao Liu genetically tweaked the microbe with a suite of genes into  that can be controlled by adding trace amounts of nickel to the growth media.

“Genetics is a very powerful tool,” said Liu. “We have created a very flexible system that we can finely control.”

The genes were taken from a mortal enemy of bacteria — a bacteriaphage — that infects the microbes and eventually kills them by causing them to burst like balloons. It’s the first time scientists have used such a specialised bacterial system and placed it in cyanobacteria to cause them to self-destruct.

“This system is probably one of a kind,” said Curtiss, who with Liu has filed a patent on the technology.