Program Two: "Keepers of the Biosphere"

Oceans of Microbes (Part 5 of 10)

Dr. Steven Giovannoni finds microbes in the most unusual places in the ocean and attempts to grow a mystery microbe in the lab.




{Title: Oceans of Microbes}

Narrator, Lillian Lehman: The great majority of the ocean's living matter, by weight, consists of microbes. More then all the lobster, fish, porpoises, and whales combined. Think about what will happen when these krill die. Will they all be eaten? And what will happen to the eaters when they die? Marine scientist have known for a long time, that when fish die, they sink to the bottom, and by the time they get to the bottom, they've decomposed into their essential chemical elements. So one thing the profusion of ocean microbes is doing, is decomposing all the dead material floating down from above. In fact that is how all the fish nutrients get releases back into the water, so they can be recycled and used by other fish. If microbes exist in the oceans in massive numbers, and since the oceans cover seventy percent of the Earth, can there be any question that marine microbes play a vital role in the health of the planet, and the health of humanity. But what exactly do they do? There are many clues, but at present scientist know very little. This man has dedicated his scientific life to filling the vacuum. Steve Giovannoni, a marine microbiologist at Oregon State University, grew up around the ocean.

Scientist, Steve Giovannoni: So, there is a real sense when you look out across the sea, that here's a mysterious thing that is very big, bigger then most of the other things in your life. Those mysteries are important for people, the ocean was important to me in that regard. The thrill of the hunt really begins when you get the idea that, maybe your seeing something that is very new.

Narrator, Lillian Lehman: A generation ago, scientists knew almost nothing of microbes in the ocean. Most doubted that there was anything new to discover out there at all.

Scientist, Steve Giovannoni: There were plenty of skeptics. There were people that thought that, the kinds of bacteria that we already knew about, were a perfectly good example of what lived in the oceans.

Narrator, Lillian Lehman: Even as a graduate student, Giovannoni was convinced that was short sighted. And he was excited by a new discovery of life in the deep. Over two miles down, seen here in animation, scientists from Woodhull Massachusetts, found underwater volcanoes. Spewing super heated minerals from the Earth's core. When these minerals meet the ice cold water, they crystallize. Creating huge undersea structures. Spotlights pierce the blackness, this is real film. There is no sunlight, yet life blooms in the darkness. How? Microbes. Instead of sunlight, hydrogen and sulfur, from volcanic vents, provide the energy for microbial life. The bacteria become food for some of the larger creatures. And form the base of the food web. Shrimp, fish, and crabs, thrive in this oasis of heat, and microbes.

Scientist, Steve Giovannoni: But, seeing what could happen there. That there could be this unique ecosystem based on microbial life, stimulated me to think about, the kinds of mysteries that might be right under our nose.

Narrator, Lillian Lehman: In a nineteen eighty nine, research voyage to the the Sargasso Sea, in the south western part of the north Atlantic. Giovannoni sniffed the first scent of success. Though he barely knew it at the time. As beautiful as it is, the Sargasso might seem a poor candidate for a place to find new life. The Sargasso is very low in nutrients but that's the point. It's not unlike most of the large central areas of the world's oceans. And since that's most of the planet, its what Giovannoni wants to know about. What's going on out there.

Scientist, Steve Giovannoni: This is what most of the open ocean, realy is like. Where nutrients are very low in abundance. The reasons for this has to do with the motions of water. As you get nearer the edges of the continents, cold water, deep water comes up to the surface, currying nutrients. That doesn't happen here, in the center of the Atlantic Ocean. Sometimes those nutrient rich waters are brought up by a really big storm, but most of the time, they are held below by the warm, lighter nature of the water above. So, warm water is lighter, it sits like a blanket over the cold deep water carrying the nutrients. Keeps it down there, this means that the ocean surface around us is very, very clear, its the color of really pure water. The low nutrient environment presents a challenge. Finding and identifying microbes, is that much harder. Like all scientists, Giovannoni and his team are forever optimistic. Something new may be found, that will make their mark.

Scientist, Steve Giovannoni: It didn't thread. There we go. There are a lot of bacteria out there, but in comparison to the continental shelf. Close to the coast of the Unites States, this water has far fewer algae in it. Far fewer nutrients in it, and the organisms that live here, have to recycle what they've got.

Narrator, Lillian Lehman: Giovannoni has a hunch, that in the low nutrient Sargasso Sea, evolution might favor very small microbes. Theoretically smaller means better, in such an environment.

Scientist, Steve Giovannoni: Organisms in the open ocean have special features that enable them to grow and compete, my favorite hypothesis is that the smallest of the cells have a certain advantage over everything else. Because their surface area is high, relative to the inside of the cell. And its the surface of the cell, that the cell uses to capture nutrients out of the surrounding water. Those cells are going to grow the fastest.

Narrator, Lillian Lehman: Giovannoni's hunch was astute, in one of his sample jars, he had captured one of the first specimens ever, of a previously unknown bacteria. As if living the reverse every angler's favorite story, he was soon to qualify for the man who caught one of the smallest bacteria known to science. He and his team were about to make discoveries.

{Title: A Mystery Microbe.}

{Sounds of traffic.}

Narrator, Lillian Lehman: Giovannoni and his team have returned to Oregon State University, to pan for microbial gold, among the samples of water from the Sargasso Sea. But how do you know when you've found a new microbe anyway? Searching with a microscope is not realistic, because so many different types look the same. Imagine this is Giovannoni's mystery microbe unrecognized in a sample of the Sargasso water. When he looks, he can't identify his quarry simply by physical appearance.

Scientist, Steve Giovannoni: We had to find some other way of identifying them, and what we did was to become gene hunters. In place of the organisms, we began to hunt their DNA.

Narrator, Lillian Lehman: Giovannoni chemically broke open millions of different microbes. The messy results were billions of different DNA fragments all mixed together.

Student, Brian Lanoil: What we are looking at here is approximately fifty billion cells worth of DNA. So in order to be visible to the human eye, you need to have a lot of DNA on there, a lot of cells.

Narrator, Lillian Lehman: DNA is a complex genetic recipe that consists of two strands held together by four Chemicals called nucleotides, which are like puzzle pieces. The length, and arrangement of these four Chemicals, determines the identity of every living thing on Earth.

Scientist, Steve Giovannoni: We removed the DNA from the microorganisms in the seawater and we took single genes. We took single copies of genes from all that DNA, and we studied those single genes, and we did it by reading the code on the gene.

Narrator, Lillian Lehman: Giovannoni retrieved pieces of DNA, with just enough chemical code to analyzing. He compared these with a up to date database of existing codes. The genetic codes of all known living things. One by one the DNA codes matched existing organisms, but one code did not match up. It belonged to an unknown organism. They had discovered the existence of the mystery microbe. They named it SAR eleven - Sargasso gene Number eleven Now the real work would begin. He had to find the whole microbe. It wasn't long before the search took on greater significance. Giovannoni’s research team found SAR eleven in water everywhere they looked, and they knew it was a bacterial plankton, which means it is involved in some way with the supply of nutrients to algae, the oxygen producers of the sea.

Scientist, Steve Giovannoni: How is SAR eleven related to algae? You could say that algae are one half of the cycle. And SAR eleven, is probably the other half of the cycle. What would happen if you took away one half of the cycle? The cycle would stop.

Narrator, Lillian Lehman: Following Giovannoni's lead, other scientists found the same gene in ocean samples from around world. Evidence even turned up in freshwater lakes. Even more remarkable, in every sample of water there were more SAR eleven genes than genes from any other organism. Giovannoni realized that he was on the trail of possibly one of the most abundant life forms on the planet.

Stephanie Connon: Right now all we know about SAR eleven is one gene, and we know that that gene is out there in the sea.

Narrator, Lillian Lehman: Stephanie Connon is a graduate student in Giovannoni's laboratory.

Student, Stephanie Connon: We feel that it is one of the most dominate organisms in the open ocean ecosystem, and being a dominate organism, means that it is the most numerous one. We feel it plays an important role in the food web in the ocean, and we would like to find out what that role is.

Narrator, Lillian Lehman: But so far, they hadn't managed to grow SAR eleven, and for over a century, the only way to study microbes was to grow them.

Scientist, Steve Giovannoni: This is one of the oldest methods in microbiology. It’s called a spread plate. And really all it is, is dropping water from the environment on a surface of a sterile plate, contains food for bacteria, separating the bacteria so that they grow up by themselves, and form colonies that we can see with our eyes.

Narrator, Lillian Lehman: One week later. So many bacteria have grown that they become visible. For years marine microbiologists believed that the colonies which grew like this, on spread plates, revealed all the microbe species in the ocean. The reality was different. Over ninety nine percent of all microbes on Earth will not grow this way.

Scientist, Steve Giovannoni: I know more about SAR eleven's genetic makeup then I do about its appearances, or its activity in the ocean surface. Making that transition from, from studying genes to studying cells is one of the challenges of our work. The real challenge today is to try to grow SAR eleven. Something about these cells makes them unable to grow in the scientific laboratory, at least today, using the kinds of techniques that scientists have. I told Stephanie this. I said, ”what would be really a great discovery, but Challenging, and require creative thought would be, to try to isolate these organisms for the first time. Do you want to do that project?” And she said "yes".

Student, Stephanie Connon: What I do in the laboratory is, I try to grow these unknown organisms, unknown bacteria from seawater. We are going to be testing different food sources for this organism. To determine what it eats. And if we can do that, we can start determining what its role is in the food web.

Scientist, Steve Giovannoni: Our hypothesis is, that SAR eleven eats organic carbon, but what we don't know is what kind of organic carbon does it eat. What does it like to eat? And that’s one of the things Stephanie has to figure out in order to make it grow.

Narrator, Lillian Lehman: If Stephanie's diet for SAR eleven does get it to eat, grow and reproduce, they will be able to find out, much more about what the microbe actually does. Unlike many microbes, SAR eleven thrives with very little nutrients, so Stephanie is tempting it with very small amounts of food, one thousand times less than normal. But it’s a stubborn microbe.

Scientist, Steve Giovannoni: We think that the reason it's so difficult to grow in the laboratory is that, possibly SAR eleven is a small cell, built to live at the very low nutrient concentrations that are found in the open ocean sites that we study, and that it’s precisely adapted to do one thing, and if we change anything then it doesn't divide in the lab. So the trick for us will be to somehow, or another reproduce exactly what's happening out in the ocean in order to make it grow.

Narrator, Lillian Lehman: Brian Lanoil, is looking for an alternative way to snag a whole SAR eleven microbe. his approach is once again to use SAR eleven's DNA as the tool.

Scientist, Steve Giovannoni: Your going to stain for thirty minutes.

Narrator, Lillian Lehman: For the plan to work, he must first succeed in getting a larger DNA fragment.

Student, Brian Lanoil: Yeah, it's a really nice unit too.

Scientist, Steve Giovannoni: In the past we studied small pieces, but we could never study the DNA an organism as one big piece. But this device gives us a way of working with very large pieces of DNA. And if it works, then Brian is going to use those big pieces of cloned DNA, as a way of making SAR eleven light up under the microscope. We got everything worked out, but the one thing we're missing is these great big chunks of SAR eleven DNA. We've been unlucky, and that is how it is some times, in science. We keep missing it, we get other pieces of DNA, but we keep missing the SAR eleven, big chunks. So we got to try again. Fishing, is what it is.

Narrator, Lillian Lehman: If Brian can find a large chunk of SAR eleven's DNA he will try and hook a whole microbe, using the DNA fragment as bait. He will give the DNA fragment luminescence, like that of a fire fly. With luck, the DNA probe will find a SAR eleven within the mix of marine microbes, and enter it. The probe should then find a matching DNA sequence, and like a key in a lock bind itself to this chemical sequence. The entire microbe will light up, and Brain will be able to see, and photograph SAR eleven, under a microscope.

Student, Brian Lanoil: I change it once every couple of months, Yeah.

Scientist, Steve Giovannoni: Now and then. Hey, it looks like Brian has got some pretty big DNA, it looks like.

Narrator, Lillian Lehman: Suddenly it seemed like, Brian had found his large DNA fragment.

Scientist, Steve Giovannoni: Well it's looking good, but we're gonna look at, we have to look at, the markers, and find out how big it is.

Student, Brian Lanoil: The largest is twenty two hundred KB.

Narrator, Lillian Lehman: But this one proved a blind alley. They were unable to confirm that it belonged to SAR eleven. As so often in scientific work, they had to try again, and then again.

{Music with a synthetic wind and percussion instruments.}

Scientist, Steve Giovannoni: Yeah, just keep doing it.

Narrator, Lillian Lehman: In the end it was Stephanie, using a variation of Brain's technique, that struck gold. Seven years after they first discovered a single SAR eleven gene, the mystery microbe revealed itself, and pose for its photograph.

Scientist, Steve Giovannoni: Under the best microscopes, SAR eleven is nothing more than a pinpoint of light. It's like looking up at night and seeing a star in the sky. And my feeling was like being the first person to land on the moon. It was like discovering for the first time organisms that you knew were tremendously important out there, that were present in numbers that went beyond the billions, and yet had not been detected at all, by anybody previously on the planet. And they're a lot smaller than most of the other bacteria out there. In many cases, they're a thousand times smaller. You could put a million billion of them into a tablespoon. What's it doing out there?

Narrator, Lillian Lehman: What is SAR eleven doing out there? That's a question that applies to the vast majority of microbes on the planet. We know they have great power throughout the globe, but we often know few of the details. When we do, the details can be amazing. For example microbes in the ocean, effect the temperature of the planet. Ocean algae produce a sulfur compound that escapes into the atmosphere. In the atmosphere, the sulfur particles cause moisture in the air to form cloud droplets. With many droplets it's a very white cloud. With just a few its dark. The degree of whiteness, affects how much of the sun's light, and heat, are reflected from Earth back into Space. One of the things that controls the Earth's temperature. So microbes have the power to affect climates. And its always been that way. Long before there were animals or plants, or fish, or insects. When dinosaurs were still hundreds of millions of years in the future. Microbes transformed the Earth's atmosphere. From a unbreathable mixture of noxious gases to the oxygen based air used by all the larger life forms, that were to follow. Microbes have the power to control the evolution of life on the planet, but our understanding is only on the first page of the book of knowledge. And this was dramatically proven by Biosphere 2. What did go wrong there? We know that the oxygen levels dropped by almost a third in only a few months. Causing an extinctions of species within Biosphere 2. Yet a conscious effort had been made to introduce, plant, animal, and insect species, that would successfully form a food web, a Web of Life. But microbial species were added almost inadvertently. Most of them like Earth's, virtually unknown. the microbes did what they are supposed to do. We created an imbalance, by over feeding them. Other factors probably came into play. But there is a strong suspension, that insignificant part, one of human kind's most ambitious experiments was brought down by, in effect, by a compost heap. Over fertilization of the soil, created a microbial feeding frenzy. Reproduction increased dramatically, to billions of trillions. This impacted the oxygen cycle. One microbe hardly makes a difference, but trillions of rapidly reproducing bacteria, consumed a huge amount of of the oxygen within the enclosed ecosystem. Was Biosphere 2, a failure? Yes, and no.

Scientist, Steve Giovannoni: Biosphere 2 gave us a opportunity to begin developing ideas that we need to understand how our own biosphere works in detail. Can we afford not to understand what microorganisms are, or what they do? Up until now we've gotten by without understanding them. But we take for granted that Earth's biosphere, will continue to hum along into the future, without sorts of significant problems, that cause almost devastating trouble for Biosphere 2. Can we permit them to remain a mystery? Before we begin predicting how our own biosphere will respond, to human influences, we have to find out what these organisms do. Without the microorganisms, there could be no plant life, there could be no animal life, we would disappear.

{Vocal harmonic tunes, and music.}

Narrator, Lillian Lehman: The message is unmistakable, the microbial world is far more powerful then we sometimes realize. We've seen this power before. When the atmosphere of the whole planet was transformed, with oxygen, it was microbes that did it. When a forest ecosystem regenerates, after raging fires destroy it, it's microbes that that spin the new web. It is microbes that enable every morsel we eat, every breath we take. There are always lessons to be learned, after all, wisdom begins at the moment we accept what we don't know. Especially about the true Keepers of the Biosphere.

(Transcript provided by Tyler Anderson)



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