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REUTERS

A man in Haikou, China, hauls recyclables. Someday plastic may come from microbes.

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Plastics made by microbes

Plastics are ubiquitous in the modern world. They serve myriad purposes, keeping our food fresh and making our electronics work. But, like gasoline, plastics come from oil, a limited resource. Without oil, where will we get plastics?

Three scientists presenting at the 109th general meeting of the American Society for Microbiology report on the possibility of plastics made (or broken down) by naturally occurring microbes.

Mark van Loosdrecht of Delft University of Technology in the Netherlands uses bacteria to transform organic waste into plastics. Agriculture, industry, and households produce waste that, at best, is turned into biogas, he says. At worst, it’s treated and thrown away – truly wasted. Dr. van Loosdrecht sees this organic material as a possible base for plastics. Certain bacteria naturally turn the sugars and fats found in organic waste into a kind of biodegradable polyester. The high cost of production has made harnessing these bacteria’s plastic-producing abilities difficult. But he has improved the bacteria’s efficiency.

Kevin O’Connor at University College in Dublin, Ireland, has tackled the same problem. Only he’s not feeding organic waste to his microbes; he feeds them regular plastics. First, he heats fossil fuel-based plastics in the absence of air. That breaks molecular bonds, turning the plastics back into oil. He then feeds that oil to natural soil bacteria, which produce organic polyester.

Richard Gross of the Polytechnic University in Brooklyn, New York, feeds vegetable oil to bacteria. They produce a substance akin to polyethylene, the plastic commonly used in water bottles. The right enzymes turn this bioplastic into a biofuel. The process works in the lab, but it’s not yet ready for commercialization.

Also in eco-news and discoveries:

Magnetism may offer lower-energy route to refrigeration

Refrigerators and air conditioners consume large quantities of energy. During summer months in the United States, they account for half of all electricity used, and also for associated CO2 emissions. It takes a lot of energy to cool by compression. Now, writing in the journal Advanced Materials, scientists say they’re one step closer to a more efficient cooling mechanism, one that cools with magnetism.

When a magnetic field is applied to certain materials – the best are metallic alloys – they heat up. Water removes that excess heat, and the material returns to ambient temperature. Then, when the magnetic field is removed, the material cools to below the surrounding temperature. That’s your refrigeration sans compressor. Scientists estimate that magnetic-driven cooling systems would use 20 to 30 percent less energy than those using compression. And they don’t need the ozone-depleting chemicals commonly used as coolants.

So far, scientists have labored to overcome one obstacle – finding a material that cools sufficiently in a magnetic field and doesn’t wear out quickly. Here’s the breakthrough: A material’s crystalline structure determines how it responds to a magnetic field and whether the response is dramatic enough for use in cooling. Previous research tested large amounts of various materials for their cooling power.

But, say the authors, because a material’s response to a magnetic field hinges on its microstructure, scientists will likely tailor-make the perfect material from the bottom up in the future.

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