Bacteria in Volcanic Mud as Acidic as Lemons Thrives on Rare Earth Metals

Human beings need certain minerals such as zinc, magnesium, or selenium for our cells to perform vital functions. Our bodies are networks of enzymes, and we are walking chemical reactions.

In an incredible illustration of the nature of life and reality, a few years ago it was discovered that certain extremophile bacteria actually require rare earth metals such as cerium and lanthanum to survive.

What appear to be the first lifeforms known to require rare earth metals (most often used in technology) were found in extremely acidic, volcanic mud in the hot springs of the Solfatara crater in Italy.

The bacteria Methylacidiphilum fumariolicum requires cerium, lanthanum, neodymium or praseodymium as a co-factor for its enzyme methanol dehydrogenase, which the bacteria use to produce their energy. It replaces calcium as a co-factor.

A methanol enzyme that requires a rare earth metal to perform its vital energy production: that’s quite amazing, and a good sign for the existence of extreme extraterrestrial life on other planets.

According to an academic Max Planck publication:

“Methylacidiphilum fumariolicum belongs to a group of bacteria which have chosen an extremely inhospitable habitat: They thrive best at a pH value of between 2 and 5 and temperatures of between 50 and 60 degrees – conditions which are lethal for other organisms. Methylacidiphilum even tolerates pH values below 1, which corresponds to concentrated sulphuric acid.

The microbes produce their energy from methane. They have a special enzyme, methanol dehydrogenase, which processes the methanol produced in the decomposition of methane with the aid of metal co-factors. Most of these bacteria use calcium for this process.”

Researchers from the Max Planck Institute for Medical Research found that the bacteria’s enzyme methanol dehydrogenase had not calcium, but atoms of a rare earth metal in its structure: it was supposed to be calcium, but the bacteria made it work albeit the rare earth metals having a slightly larger ion radius than calcium.

“Suddenly, everything fit together,” explained researcher Thomas Barends. “We were able to show that this mysterious atom must be a rare earth. This is the first time ever that rare earths have been found to have such a biological function.”

The bacteria uses the enzyme to produce energy from methane.

“Individual amino acids have been exchanged in the amino acid chain of the methanol dehydrogenase of the bacterium. This creates more room for the metals,” Barends continued.

Continuing from the Max Planck publication:

“In addition, Methylacidiphilum digests a larger quantity of rare earths than it needs to survive. It is therefore possible that it stores the metals in the cell.

Genome and proteome analyses suggest that the Methylacidiphilum version of methanol dehydrogenase is widespread among bacteria from coastal waters. Scientists have also discovered methane-exploiting bacteria equipped with this on the leaf surface of plants. Plants can enrich rare earths and thus safeguard the supply for the bacteria. “These bacteria are possibly present anywhere there is a sufficient supply of sand, as sand is an almost inexhaustible source of rare earths,” says Barends.”

Rare earth metals are not so much rare, as they are very evenly scattered across the Earth, and not very concentrated in one spot.

They have applications in various technologies for their unique properties. They have unique luminescent, electrochemical, and magnetic properties, useful for helping technologies perform with reduced weight or energy consumption, or with greater efficiency, speed, thermal stability or durability.

For instance, this bacteria needs lanthanum to produce energy, but the silvery-white metal is one of the most reactive elements of its kind, making it useful for infrared absorbing glass, telescope lenses, special optical glasses, ect. Cerium, named for the Roman goddess of agriculture Ceres, is an abundant rare Earth element that easily oxidizes.

Doesn’t this increase the probability of extraterrestrial life, or at least extraterrestrial bacteria existing? It seems life can survive on anything.

Image credit: Max Planck, Science News, SI.Edu, Evo-Ed, Samaterials, Leadon)