Can Fungi Replace Plastics? Maybe, Say Researchers

Fungi, with the exception of shitake and certain other mushrooms, tend to be something we associate with moldy bread or dank-smelling mildew. But they really deserve more respect. Fungi have fantastic capabilities and can be grown, under certain circumstances, in almost any shape and be totally biodegradable. And, if this weren’t enough, they might have the potential to replace plastics one day. The secret is in the mycelia. Union College Biology Professor Steve Horton likens this mostly underground portion of fungi (the mushrooms that pop up are the reproductive structures) to a tiny biological chain of tubular cells. “It’s this linked chain of cells that’s able to communicate with the outside world, to sense what’s there in terms of food and light and moisture,” he said. “Mycelia can take in nutrients from available organic materials like wood and use them as food, and...

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Biological Wires Carry Electricity Thanks to Special Amino Acids

In nature, the bacterium Geobacter sulfurreducens uses  nanowires, called pili, to transport electrons to remote iron particles or other microbes, but the benefits of these wires can also be harnessed by humans for use in fuel cells or bioelectronics. The study in mBio® reveals that a core of aromatic amino acids are required to turn these hair-like appendages into functioning electron-carrying biological wires. "It's the aromatic amino acids that make it a wire," says lead author Derek Lovley of the University of Massachusetts, Amherst. Lovley and his colleagues removed the pivotal amino acids from the pili and replaced them with smaller, non-aromatic amino acids. Without these key components, Lovley says, the pili are nothing more than protein strings. "We showed it's not good enough to just make the string - you've got to make a wire," says Lovley. G. sulfurreducens "breathes" by removing electrons from organic materials and funneling them to iron oxides or to other microorganisms, much the way humans pull electrons out of organic molecules in food and dump them on oxygen. The bacteria use their pili to reach out to iron oxides or other microbes, transferring the "waste" electrons along the structure to the destination. Geobacter's pili are only 3-5 nanometers wide, but they can be 20 micrometers long, many times longer than the cell itself. Trafficking in electrons is how all living things breathe, but it is normally carried out by discrete proteins or other molecules that act like containers for shuttling electrons from one place to another. Lovley says earlier results showed the pili in G. sulfurreducens possess metallic-like conductivity,...

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