'Spacesuits' may protect microbes destined to live in space

Scientists have developed "spacesuits" for bacteria that may allow the microbes to survive space environments that would otherwise kill them. The protective suits pair live bacteria with light-absorbing semiconductors in order to capture carbon dioxide and convert it into chemicals that can be used by industry or, someday, in space colonies.

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The system, developed by researchers at the University of California (UC) Berkeley in the US, mimics photosynthesis in plants.

However, while plants capture carbon dioxide and, with the energy from sunlight, convert it to carbohydrates that we often eat, the hybrid system captures CO2 and light to make a variety of carbon compounds, depending on the type of bacteria.

The bacteria used in the experiment are anaerobic, which means they are adapted to live in environments without oxygen.

The suit -- a patchwork of mesh-like pieces called a metal-organic framework, or MOF -- is impermeable to oxygen and reactive oxygen molecules, like peroxide, which shorten their lifespan.

The hybrid system could be a win-win for industry and the environment: It can capture carbon dioxide emitted by power plants and turn it into useful products.

It also provides a biological way to produce needed chemicals in artificial environments such as spaceships and habitats on other planets.

"We are using our biohybrid to fix CO2 to make fuels, pharmaceuticals and chemicals, and also nitrogen fixation to make fertiliser," said Peidong Yang, from UC Berkeley.

Researchers developed the hybrid bacterial system over the past five years based on their work on light-absorbing semiconductors such as nanowires: solid wires of silicon a few hundred nanometers across, where a nanometer is a billionth of a meter.

Arrays of nanowires can be used to capture light and generate electricity, promising cheap solar cells.

The hybrid system takes advantage of efficient light capture by semiconductors to feed electrons to anaerobic bacteria, which normally scavenge electrons from their environment to live.

The goal is to boost carbon capture by the bacteria to churn out useful carbon compounds.

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The suit is made of a MOF mesh that wraps around the bacteria, covering it in patches. Wearing these MOF suits, the bacteria live five times longer at normal oxygen concentrations -- 21 per cent by volume -- than without the suits, and often longer than in their natural environment, Yang said.

Their normal lifespan ranges from weeks to months, after which they can be flushed from the system and replaced with a fresh batch.