How we found microbes rarer than a ticket to the moon

<classe étendue=Legendrea loyezae, a very rare ciliate that lives in the oxygen-free sediments of lakes James Weiss, Author provided” src=”–/YXBwaWQ9aGlnaGxhbmRlcjt3PTk2MDtoPTU0MA–/ xpwosAFwZHXDFZ8JvJ65IA–~B/aD0yNzk7dz00OTY7YXBwaWQ9eXRhY2h5b24-/” data-src=” RdDLw–/YXBwaWQ9aGlnaGxhbmRlcjt3PTk2MDtoPTU0MA–/–~B/aD0yNzk7dz00OTY7YXBwaWQ9eXRhY2h5b24-/ “/>

Legendrea loyezae, a very rare ciliate that lives in the oxygen-free sediments of lakes James Weiss, Author provided

You are more likely to take a trip to the Moon than to see a microbe called Legendrea loyezae under a microscope. Nasa’s Apollo program sent a total of 24 people to the Moon between 1968 and 1972. Only four people (including us) have ever found Legendrea loyezae from its discovery in 1908 to our recently published study.

Considering the expense, it makes sense that the number of people who have traveled to the Moon is low. But peeking into the microscopic realm doesn’t require a billion dollar budget, just a microscope and someone willing to sit in front of it.

Our recent study discovered 20 new species of microbes as well as 100 rare species. Each DNA specimen we find provides another piece of the evolutionary puzzle. Scientists can use this puzzle to analyze how an organism works. For example, certain genes suggest how a being breathes. Or it can give information about the organism’s place on the tree of life.

The reason so few scientists have seen these microbes is that undersampling is a major problem. This means that most research teams collect samples from only a few locations, or even one.

Our most recent investigation, which lasted two years, involved the collection and examination of over 1,000 samples. From lakes and ponds in Warsaw, Poland, to marine sediments in the North Sea and the Mediterranean off the coasts of Italy and Portugal, to chalk streams in Dorset, UK, we searched for microbes. And it paid off: we found more than 500 species, including rare and new species.

Microbiology is human history

The first life on Earth appeared in water as creatures too small to be seen by the human eye and remained that way for billions of years. Germs live all around us. They can be found in any habitat, from puddles to oceans. But there’s still so much we don’t know about them. Some of these microscopic organisms evolved from simple beings to more complex beings, eventually giving rise to all visible life around us. Others have changed little and kept their tiny size.

Microorganisms were the earliest predators on Earth, and their greedy appetites led to the evolution of more complex life in the earliest ages of Earth’s history. After the evolution of complex life, microbes became the primary food source for other creatures such as krill and plankton, which in turn are food for larger species. If the organisms at the very bottom of the food chain disappeared, all the other parts above them would also collapse.

The timescale of this is so long it’s hard to grasp. If we compressed Earth’s 4.5 billion-year-old history into a single year, life would exist on a microscopic scale until the end of October. Humans would appear on the last 30 minutes of the year, and we would be aware of the existence of microbes just under three seconds before the new year.

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The tree of life shows how organisms relate to each other. Looking at it, you can see that most life on Earth is still small-scale, with animals, plants, and fungi confined to a small cluster of branches within the eukarya group. Unlike the other two groups, archaea and bacteria, eukarya members store their DNA in the cell nucleus.

A microscopic rarity

Legendrea loyezae is in the ciliated branch of eucarya. Oxygen is lethal to Legendrea loyezae and it has tentacles that stretch and contract to catch prey. Scientists have discovered thousands of ciliated species.

Ciliates live in aquatic environments, thin water films in soils, and even places where there is no oxygen. Although their life depends on water, they can form protective structures to remain dormant until they get wet again. They are composed of only one cell and yet they are wonderfully diverse. Ciliates have some interesting hunting strategies – some types specialize in eating cyanobacterial filaments, which they suck up like spaghetti. They can swim. Others have a sedentary lifestyle, including Vorticellawhich has a stem to attach to submerged surfaces.

Some ciliated species form permanent physical relationships with other groups of organisms, which is called symbiosis. For example, they may harbor green algae inside themselves to eat the sugar the algae produce through photosynthesis. In exchange, they protect the algae from heavy algae grazers and viruses (yes, even algae can get viral infections).

Some ciliated species live in densely populated communities, especially in well-oxygenated environments. But others live in such small numbers that finding them is like looking for a thousand needles in a haystack the size of Mount Everest.

Our goal is to find as many of these rare and unusual species as possible. We use our knowledge of species ecology as clues. If we know that a microbe prefers to live in dark, oxygen-free habitats, we don’t look for it on the surface of the water where there is plenty of oxygen and light. It took thousands of hours through a microscope to find four Legendrea loyezaenot to mention a small fortune in physiotherapy for our stiff necks and aching backs.

Why germs are important

It’s easy to feel detached from invisible germs. Most of us will never see one magnified enough for our eyesight to improve. But learning about microbes has helped illuminate some of the most important scientific discoveries in history. Microbes come to life by inflicting animal and plant diseases and developing massive blooms in the sea that wipe out fish farms.

But we couldn’t live without them. Microbes are responsible for the survival of our ecosystems and their recovery after damage such as pollution or climate change. We cannot grow food without microorganisms. They clean our sewage. Some can produce antibiotics and other drugs, others are involved in the production of food.

So exploring the microbial world is well worth the back pain.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The conversation

The conversation

Genoveva Esteban receives funding from the European Union and other funding bodies. She works for Bournemouth University.

James Weiss does not work for, consult, own stock, or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond his academic appointment.

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