Self-Destructing Bacteria Key to Better Biofuels

Researchers at Arizona State University have genetically engineered cyanobacteria that dissolve from the inside out, making it easy to access the high-energy fats and biofuel byproducts located within.

The process involves programming a photosynthetic microbe to self-destruct, making the recovery of high-energy fats--and their biofuel byproducts--easier and potentially less costly.

"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 Center for Infectious Diseases and Vaccinology and professor in the School of Life Sciences. "This whole system that we have developed is a means to a green recovery of materials not requiring energy dependent physical or chemical processes."

How It Was Done:

Cyanobacteria have a multi-layer, burrito-like protective set of outer membranes that help the bacteria thrive, even harsh surroundings, creating the pond scum often found in backyard swimming pools.

In order to make cyanobacteria release its precious, high-fat cargo more easily, Curtiss and postdoctoral researcher Xinyao Liu, placed a suite of genes into photosynthetic bacteria that were controlled by the simple addition of 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 bacterial enemy, called a bacteriophage, which infect the bacteria, eventually killing the microbes by causing them to burst like a balloon. So, the scientists took the genetic code from bacteriaphoges that infect E. coli and salmonella and injected into the cyanobacteria.  And, finaly by adding nickel to the growth media, the inserted genes produced enzymes that slowly dissolved the cyanobacteria membranes from within.

Importance:

While the research is still in its early stages, this is a first-of-its kind project and the results offer distinct potential. Bypassing the need for added energy or chemicals to extract fats for biofuel production, means an elevation in efficiency, cost, and a lessening of environmental impact.

The next phase of the research is being funded by a two-year, $5.2 million grant from the U.S. Department of Energy (DOE) led by researcher Wim Vermaas, Curtiss, Liu and others from the ASU biofuel team.

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