October 3, 2018

Microbes wear ‘spacesuits’ to protect them from harsh environments

Humans wear specialised suits to protect them from extreme environments: astronauts wear spacesuits, ice swimmers wear dry suits to keep them warm and firemen wear proximity suits in the case of extremely high temperatures (such as an aircraft fire).
Scientists have created a similar sort of all-purpose ‘suit’ but for bacteria in the laboratory. This might sound counterintuitive since bacteria are associated with disease, and space-faring bacteria sounds like the start of a great sci-fi dystopian novel, but there are some useful applications to this technology.

Carbon emissions have filled the atmosphere with greater amounts of carbon dioxide than the planet can naturally break down and is artificially changing our climate. These suited bacteria could be the answer to capturing carbon dioxide emissions and turning them into useful products.
It could also be used to create chemicals that are needed to live in harsh environments. For example in space or on the planet Mars where resources of oxygen or fertilizer are hard to come by.

How does it work?

Pond algae | cc Caroline Reid

The suit mimics the same pathways as photosynthesis. Plants take carbon dioxide from their environment and use energy from sunlight to turn it into useful chemicals, i.e. carbohydrates. The suit also takes carbon dioxide and uses energy from light to make useful compounds. The final product depends on the type of bacteria used.
A system of light-absorbing arrays captures light to absorb energy that is then ‘fed’ to bacteria. They chose anaerobic bacteria, meaning that they do not require oxygen to live. (This is important in oxygen-void environments, like the vacuum of space).
The potential problem is that other bacteria are also fed by the process and compete for resources, destroying the ‘useful’ bacteria. Usually, the invasive bugs are aerobic (need oxygen to survive) and, since the useful bacteria produce oxygen, they can live off the products of the experiment.
This is why the scientists created a suit for the useful bacteria, so that is an unwelcome bug tries to invade, the shell destroys them.

What does the suit look like?

A 2D metal organic framework warps around bacteria that expands as they divide. | Peidong Yang lab, UC Berkeley | no usage restrictions

There are no armholes in this suit, instead, it is a ‘metal-organic framework’, like a wire mesh but much much smaller. Whilst wearing the suit, the good bacteria last five times longer than without them, in normal oxygen concentrations of 21% by volume.
Morella thermoacetica and Sporomusa ovata both produced vinegar (acetate or acetic acid) in the experiments. Although the scientists chose to produce vinegar as their final product, there are other options available.

“We picked these anaerobic bacteria because their selectivity toward one chemical product is always 100 %,” said Peidong Yang, the S. K. and Angela Chan Distinguished Chair in Energy in UC Berkeley’s Department of Chemistry who was part of the team that did the research. “In our case, we picked a bug that gives us acetate. But you could select another bug to give you methane or alcohol.”

This is the result of a five-year laboratory venture. The days that we will terraform the Moon using bacteria is still a long way off.

Posted in Science