Fantastic Bacteria and Where to Find Them

28 February 2017 Comments Off on Fantastic Bacteria and Where to Find Them

BY AFSHAN NABI (MBG/III)
afshan.nabi@ug.bilkent.edu.tr

Bacteria are microscopic, single-celled, magical creatures that do awesome things.

For starters, they live in our abdomens and secrete substances to kill pathogens that might want a share of our (and our gut bacteria’s) food, thus protecting us from certain diseases. They help us do a better job of extracting nutrition from our diet; rodents lacking gut microbes need 30 percent more calories to maintain the same weight as rodents that have them. And astonishingly, gut microbes can influence our brain and behavior, including our stress response.

If you still think this is nothing special, know that your “human” body contains almost 10 times more bacterial cells than human ones and that you are carrying 2-3 kg of bacteria around. And in that weight, 40,000 bacterial species are present.

It is a weird thought; you are a walking, talking and safe home for all the bacteria you carry.

To further draw you into the world of fantastic bacteria, I have compiled bits and pieces of information that might surprise and entertain you (or bore you if you are a microbiologist, so I am really hoping you are not a microbiologist!). Let’s go!

Magnetospirillum magneticum was first discovered – accidentally, like many other fantastic things in biology – in 1963. A scientist analyzing samples from a swamp noticed that some bacteria moved very rapidly from one end of the slide to the other. Normal bacteria do not behave like this; they blunder about in apparent confusion, rather than directly from one point to another, unless there is a stimulus. Subsequently, it was found that this fantastic bacterium contains magnetite, the same mineral used by human beings to make the first compasses, which allows it to migrate along the lines of the Earth’s magnetic field. Imagine if humans had that power; we would all be less impressive versions of Magneto.

The next cool bacterium on this list is Deinococcus radiodurans, a metaphoric giant of life discovered in 1956, whose name hilariously means “strange berry that withstands radiation.” It has the ability to thrive in environments with ten thousand times as much radiation as a human being could stand. An extremely efficient DNA repair system, which allows it to “mend” back together again the DNA “broken” by radiation, is the main reason for its resistance to colossal amounts of radiation.

Since bacterial hunger for life is immense, D. radiodurans can also slog through and overcome drought, high and low temperatures, acids and a state of vacuum. The “Guinness Book of World Records” calls it “the world’s toughest bacterium.”

In 2003, scientists translated a song, “It’s a Small World,” into a number of DNA segments and inserted these into D. radiodurans. They were able to retrieve the sequence without any errors a hundred bacterial generations later. This was done to prove that D. radiodurans could be used as an alternative information storage unit in case of nuclear catastrophe wiping out all electronic data. Unfortunately, many separate colonies had to be created, since each could contain only a small part of the song encoded into their DNA. Furthermore, each colony had to be kept separate to prevent competition. Over generations, it is very likely that some colony would prove dominant over others, leading to subsequent loss of “weaker” colonies and the crucial information stored in their DNA.

In 2006, 2.8 kilometers deep in a South African gold mine, researchers found, for the first time, a self-sustaining community of bacteria that had been cut off from the surface of the earth for many millions of years. All their energy was derived from radioactive rocks; they had never seen the sun, and when they finally met oxygen, they clearly did not like it much, because it killed them. Such bacteria survive exclusively on hydrogen and sulfur compounds; as one researcher commented, “For them, it’s like eating potato chips.” The reason this discovery was so thrilling is that it proves that life can exist deep underground on planets whose surfaces are dead.

Cupriavidus metallidurans is a bright figure in the bacteria world as seen from a common human perspective; it plays a role in the formation of gold nuggets from a solution containing gold. Such a solution is toxic to most other microorganisms. Unfortunately, to get the gold, a solution of gold is still needed. Scientists believe that precipitation of gold from the solution might be a mechanism the bacteria use to detoxify their environment. How they perform this metallurgical miracle is as yet unknown. Other bacteria related to C. metallidurans are resistant to metals like cobalt, zinc and cadmium. Ongoing research is looking at ways to use these bacteria as sensors and as a remedy for the heavy-metal pollution caused by human beings.

To think that this planet is still crawling with bacteria, the oldest form of life, and that they can perform actions that seem like miracles to us, is at the same time both sobering and exciting. The tenacity of bacteria in clinging to life, the tenacity of life itself is astonishing. Bacteria have been found in the “sea-bed, rocks, salt deposits, permafrost, glaciers and ice-cores, bricks from ancient temples, old tins of meat, herbarium samples, and beer from sunken ships.” Consider all of these, and the 40,000 species from our tummies, and the fact that some estimates place the number of microbial species on the planet in billions.

What else might be lying undiscovered on this incredible Earth of ours?