Photosynthetic humans--endowed with the power to derive energy from the sun--are a popular construct of science fiction. But Pamela Silver, a biologist at Harvard Medical School, aims to push that concept into reality.

Silver's research focuses on cyanobacteria, a microbe responsible for almost 50 percent of the earth's photosynthetic ability. Her team aims to harness the organisms' photosynthetic powers by engineering them to generate fuel and other valuable chemicals.

But Silver is also experimenting with a more fantastical use for the microbes. In a recent experiment, researchers injected fluorescently labeled cyanobacteria into zebrafish embryos, a species commonly used in research. The fish are transparent, making them easy to observe during development. Much to Silver's surprise, the fish survived and grew, as did the fluorescent microbes living inside their cells. "When we put E. coli into fish, they blew up, but they are extremely tolerant of cynabacteria," Silver said at a synthetic biology conference in Boston last week, where she presented the research. Right now, the system doesn't make enough energy to maintain the fish, but the researchers are experimenting with different engineering approaches to enhance production.

The video below shows Zebrafish embryos (green) that have been injected with photosynthetic cyanobacteria (red).

The ability to run on sunlight would certainly be a handy superpower. But what if you still like to eat? James Liao, a biologist at UCLA, has developed a new strategy to enhance cells' ability to burn fat by adding a metabolic pathway from bacteria and plants. (For more details, see Making Fat Disappear.) "Female mice show a huge decrease in diet-induced obesity, and they accumulate much less fat," said Liao at the conference. Results for male mice are less dramatic, though it's not clear why.

According to Chemical and Engineering News, California-based synthetic biology company Amyris has filed an application with the Securities and Exchange Commision for a $100 million public offering.

Read about the company's move to Brazil in Technology Review's March/April issue here. An excerpt:

Less well publicized is that Amyris has raised more than $170 million in venture capital to get itself into the biofuels business and that its current plans call for producing nearly all that fuel in Brazil. Roel Collier, a Belgian fluent in Portuguese who heads Amyris's Brazil operations, points to a 12-meter-tall steel tank in which genetically modified yeast is feasting on the juice of the sugarcane that is so abundant in this country. "Inside is cutting-edge American technology applied to the competitive advantage of Brazil," he explains.

For the last two years, Collier's responsibilities have included shipping drums of frozen Brazilian sugarcane juice to Amyris's California laboratory, some 10,000 kilometers away. There, scientists have been genetically rewiring ordinary yeast cells to digest caldo de cana, as the juice is called, and turn it into farnesene, a fragrant oil that Amyris has shown can be converted into diesel fuel. In the fast-moving field of synthetic biology--a discipline that looks to rewrite the DNA of microörganisms as if it were computer code--the California laboratories of Amyris are considered state of the art.

Students from Cambridge University, in England, engineered bacteria to produce pigments in all colors of the rainbow (shown above) as part of the International Genetically Engineered Machines Competition at MIT. Credit: Mike Davies

Bioengineering students from around the world converged on MIT this weekend in what has become an annual ritual in synthetic biology--iGEM, the international genetically engineered machines competition. Among the finalists this year were "GluColi", a new generation of glue made by bacteria, a biological version of an LCD screen made of yeast, and a multicolored menagerie of bacteria that might ultimately become part of a biological system designed to change color in response to toxins or other target compounds, providing an easy-to-read warning system.

By combining snippets of DNA, dubbed biological "parts", students build microbes designed to perform useful functions, such as producing medicines or detecting toxins. Each year "parts" built for the competition are entered into a biological library, so that next year's teams can use them to build even more sophisticated machines. As iGEM co-founder and MIT bioengineer Tom Knight explained in a previous piece, "The key idea here is to develop a library of composable parts which we think of in the same way as Lego blocks. These parts can be assembled into more-complex pieces, which in many cases are functional when inserted into living cells."

Entries into previous years have included yeast designed to produce beer with the health benefits of red wine, sweet-smelling E. coli, a commonly used research bacterium with a vile odor, and probiotic bacteria, like that found in yogurt, designed to fight cavities, produce vitamins, and treat lactose intolerance.

To make multicolored microbes, students from Cambridge University, in England, mined bacterial genomes for pigment-producing genes. They then engineered those genes into the harmless strain of E. coli used in genetic research. Carotinoid enzymes co-opted from Pantoea ananatis, a bacterium that can rot onions, generated red and orange pigments. A gene for melanin, an enzyme from the soil bacterium Rhizobium etli, produces brown. Chromobacterium violacein, a soil and water dwelling microbe offered genes capable of producing shades of violet, green and blue.