October 23, 2015 | David F. Coppedge

Microbes Are Wired for Communication

New findings show surprising communication systems between bacteria, including power grids with tiny electrical cables.

Bacteria in the world’s oceans produce millions of tons of hydrocarbons each year (Science Daily). The oceans maintain a balance between hydrocarbon-producing microbes and hydrocarbon-digesting microbes. “The scientists argue that the cyanobacteria are key players in an important biogeochemical cycle, which they refer to as the short-term hydrocarbon cycle,” the article says, surprising most readers. “The study suggests that the amount of hydrocarbons produced by cyanobacteria dwarfs the amount of crude oil released into the seas by natural seepage or accidental oil spills.”

Single cell activity reveals direct electron transfer in methanotrophic consortia (Nature): Pass the electrons, please. Methane-digesting bacteria don’t just share molecules by diffusion; they pass electrons between each other. Ocean sediments contain vast numbers of these archaea and bacteria whose symbiotic actions in oxidizing methane have global effects. The researchers from Caltech and NASA find that “the metabolic interactions underpinning the environmentally important microbial symbiosis responsible for the anaerobic oxidation of methane” are electrical in nature.

Nano power grids between bacteria: Microorganisms in the sea organize their power supply via tiny power-cables, thus oxidising the greenhouse gas methane (Science Daily). As if not surprising enough to see electricity flowing between methane-digesting microbes, another team from Max Planck has determined that they use electrical cables on a nanoscopic scale: “the smallest power grids in the world” with an important job. “They consist of two completely different cell types, which can only jointly degrade methane,” the article explains.  “Scientists have discovered wire-like connections between the cells, which are relevant in energy exchanges.” The Max Planck team worked together with the Caltech team to observe the tiny wires, called pili.

With length of several micrometres the wires can exceed the length of the cells by far, but their diameter is only a few nanometres. These wires provide the contact between the closely spaced cells and explain the spatial structure of the consortium, as was shown by a team of researchers led by Victoria Orphan from Caltech [see the Nature paper].

Methane is a potent greenhouse gas. Without these teams working to turn it into carbonates, the global climate might warm the planet excessively. Did this “consortium” of two different kinds of microbes exist in the early earth, before they think oxygen was abundant? They’re not sure; “Yet today it remains unknown how the anaerobic oxidation of methane works biochemically.”

The electrical power grid they found may not be unique in the microbial world (See also 11/10/12, “Very Unreal and Fantastic”: Electric Cables Created by Bacteria). The article explains why this power grid is important:

Consortia of archaea and bacteria are abundant in nature. Our next step is to see whether other types also show such nanowire-like connections. It is important to understand how methane-degrading microbial consortia work, as they provide important functions in nature,” explains Antje Boetius, leader of the research group at the Institute in Bremen.

Biologists discover bacteria communicate like neurons in the brain (Science Daily). Yet another team from UC San Diego found that biofilms act as if they are a super-organism, passing molecules between one another something like neurons in the brain. Both take advantage of ion channels in cell membranes as portals for sharing information. Biofilms, which are like cities of millions of microbes organized with inner and outer layers, communicate electrically to stay intact under stress. Noting that glutamate is one of the molecules distributed in the biofilm led the researchers to “speculate that the metabolic coordination among distant cells within biofilms might involve a form of electrochemical communication. The scientists noted that glutamate is also known to drive about half of all human brain activity.” Waves of electrically-charged potassium ions also pass through the cells’ ion channels, just as they do in neurons. “In this way, the community of bacteria within biofilms appears to function much like a ‘microbial brain’,” they say, as “long-range electrical signals” pass through the colony.

Update 10/24/15: A new species of methane-metabolizing organisms was found off the coast of Australia, Science Daily reports. The ‘fundamentally different’ organisms were found 600 meters below the Earth’s surface in a deep coal seam aquifer; “these new organisms played an unknown role in greenhouse gas emissions and consumption” till now. The discovery will rewrite the textbooks, researchers feel; it shows how little is known about carbon cycling by microbes.

Update 10/23/15: On ID the Future today, the host reads fascinating facts about electricity in the living world from Geoffrey Simmons’ book Billions of Missing Links.

Microbes are unsung heroes of the planet. We tend to dislike them, because a few of them we call “germs” cause disease. We don’t like biofilms that form on our teeth (tartar) and inside pipes. But thank God for microbes, because they play a huge role in moderating the climate and forming the building blocks of continental crust. They are just as important in the soil, in your gut, and in the air as in the ocean.

The vast majority of microbes are beneficial. After the fall of the “very good” creation, and especially after the stress of the Flood, it’s possible some mutated and got out of balance (see the commentary about cholera [11/01/13], for instance—a microbe with a good function in the wrong place). It’s likely that the earth would not even be habitable without microbial consortia in place from the beginning.

To find now that microbes work in gigantic tightly-knit communities involving members of different kingdoms (archaea and bacteria) working together in harmony is surprising enough. To learn that they communicate over electrical cables in nanoscopic power grids is nothing less than astonishing.  We may have to re-think the way we categorize these little cells. Their organization resembles super-organisms with brains, as if they are giant, purposeful beings with huge roles to play on the global stage.

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