Cyanobacteria from Pond to Lab - Pondlife Ep 2
PONDLIFE – Episode 2 - Cyanobacteria
[ELECTRONIC MUSIC]
[American Museum of Natural History logo animates on and off over footage of ducks and turtles swimming in a greenish lake.]
[Animation of hand dipping a sample cup into water.]
[Animation of a pipette putting a drop of water onto the slide of a portable microscope.]
[ELECTRONIC MUSIC AND SOUND OF WATER DROPLET]
[Animated view through a microscope’s eyepiece. The title “PONDLIFE” resolves into view, surrounded by microscopic organisms.]
[MICROSCOPE SLIDE CLICKS INTO PLACE]
[Joggers and bicyclists move along roads in Central Park. New Yorkers and tourists enjoy the Park and the view of the city skyline.]
SALLY WARRING (microbiologist): We are surrounded by hidden microscopic worlds filled with fascinating life forms.
Thousands of microbial organisms live within a single drop of water.
[A fountain bubbles outside of the American Museum of Natural History’s 77th Street entrance, the name of the Museum is partially visible through a tree. Dr. Sally Warring walks out of this entrance towards the street.]
WARRING: On Pondlife, we’re going on a safari to explore the microbial wildernesses that exist all around us.
[Warring speaks to camera in Central Park.]
WARRING: Today I’m out looking for a group of organisms that evolved over two billion years ago.
These organisms were the first to live by photosynthesis.
[Looking towards the sky, sunlight is visible through the leaves and branches of trees. A bee crawls along small yellow flowers.]
WARRING: That’s the process of using sunlight to make sugars…
[Mandarin ducks swim on the surface of a pond.]
WARRING: …and then those sugars are used to power the cell.
[Turtles sunbathe on a rock in a pond.]
WARRING: …A byproduct of photosynthesis is oxygen…
[Warring speaks to camera.]
WARRING: …and two billion years ago these organisms became so abundant that they completely changed the Earth’s atmosphere.
It went from one that was very oxygen-poor…
[View of the New York City skyline from a bridge in the Park. Visitors on paddle boats move along The Lake.]
WARRING: …to the oxygen-rich atmosphere that we live in today.
[Warring speaks to camera.]
WARRING: These microbes are called cyanobacteria and lucky for me, they are just as abundant today as they were two billion years ago.
In fact, I haven’t had to go very far at all to find them.
[Warring walks along large rocks in the Park to a lake. ]
WARRING: I’ve simply walked out the door, I’ve crossed the road, and I can already see a pond that is teeming with cyanobacteria.
[Text identifies a greenish body of water as “The Lake, Central Park, New York City.”]
[Close-up footage of the surface of The Lake shows a slimy green film. Warring approaches the edge of The Lake and examines it.]
[BUBBLING ELECTRONIC MUSIC]
WARRING: You can find cyanobacteria all over the world.
There are currently around 3,000 described species with different morphologies and habitats from freshwater ponds to arctic oceans. They even live in soil.
[Warring climbs some large rocks near the edge of The Lake.]
WARRING: As I wander around Central Park, I’m on the lookout for signs of cyanobacteria.
[LILTLING ELECTRONIC MUSIC]
[Warring approaches a different edge of The Lake and fills a small glass container with water. She turns to the camera to speak.]
WARRING: It’s cyanobacteria that are making this pond so green.
If you look closely at this water sample…
[Closeup of water in container. It has a greenish hue and is cloudy with small particles.]
WARRING: …you can see that it’s full of tiny, floating, green particles.
Each one of those particles is a colony of cyanobacteria and each one of those colonies is made up of multiple individual cyanobacterial cells living together.
[Warring sits on a rock near the lake, sets down her water sample, and removes a field microscope from her bag.]
WARRING: To find out what species of cyanobacteria is living here I’m going to have to put it under the microscope.
[Warring prepares a glass slide with a drop of water from the sample, then raises the microscope to her eyes.]
[Under the microscope, groupings of small brownish-green dots float against a white background. Text identifies them as “Microcystis.”]
WARRING: The cyanobacterium blooming in the Lake belongs to the genus Microcystis. Microcystis colonies are made up of many individual cells suspended in a clear mucus.
[Closeup of a single colony of Microcystis, which is a clear, circular, gelatinous-looking shape with even smaller green circles within it, these are individual cells.]
WARRING: A colony may start as one cell…
[Closeup of a single greenish cell.]
WARRING: …which divides to become two cells…
[Now two cells are connected to one another.]
WARRING: …then four…
[Now there are four adjoining cells.]
WARRING: …and so on until some colonies are large enough to see with the naked eye.
[POPPING ELECTRONIC SOUNDS]
[Colonies of Microcystis float against a white background.]
WARRING: The colonies grow fast in warm summer waters, and when their numbers get dense enough, we call this a bloom.
[Microscopic view of many differently-shaped colonies of cyanobacterial species moving slowly.]
WARRING: Many cyanobacterial species are bloom-forming, and you can distinguish each species by their unique colony shapes.
One advantage of living as a colony is that when many individuals live together, tasks can be divided among the members.
We can see this in another cyanobacterium from the lake.
[A colony made of a strand of individual greenish-brown cells coiled into a spiral moves across the screen. A few cells within the strand are more circular shaped and lighter green than the others.]
WARRING: This one belongs to the genus Dolichospermum, and among its helical colony, some cells look a little different from the rest.
[Microscope focuses on these different, lighter green cells.]
WARRING: These specialized cells are called heterocysts and they have given up their photosynthetic ability to focus on the task of absorbing nitrogen.
They build that nitrogen into molecules that can be shared and used by all the cells in the colony, and in return the other cells share the sugars gain through photosynthesis with the heterocyst.
By dividing up these tasks, each is run more efficiently, and the colony can prosper.
[UPBEAT ELECTRONIC MUSIC]
[Back in Central Park, Warring packs up her field microscope and walks through the park to a different water’s edge. She uses a pipette to pick up some green algae from the water.]
WARRING: Thousands of visitors walk through Central Park every day, mostly unaware of the many tiny dramas playing out all around them.
[Warring prepares a microscope slide with the sample she has collected.]
WARRING: With a microscope, we can catch a glimpse into these unseen worlds.
[Warring lifts the microscope to her eye.]
WARRING: The bloom in the next pond is dominated by a cyanobacterium from the genus Aphanizomenon.
[Under the microscope, several long strands of green-brown cyanobacteria colonies drift slowly.]
WARRING: Aphanizomenon forms long, thin, filamentous colonies.
And while at first they appear to only drift, under time-lapse we can see just how busy they are.
[With time sped up, the colonies move more quickly. Some small organisms move amongst the colonies.]
[RUSTLING ELECTRONIC SOUNDS]
WARRING: There is a good reason to stay on the move.
Cyanobacteria sit at the base of the food chain and are good eating for a number of small predators.
This ciliate is a specialist cyanobacteria predator.
[The microscope focuses on a small circular ciliate, green-brown in color with a clear membrane around it.]
WARRING: It’s from the genus Nassula and it’s using its sensitive cilia to feel out a filament, searching for an end.
[The ciliate feels its way along one of the long thin cyanobacteria colonies.]
WARRING: Once located, it begins its work, sucking in the cyanobacteria like a strand of spaghetti.
[WHIRRING ELECTRONIC SOUND]
[The ciliate finds the end of the filament and begins consuming the cyanobacteria, coiling the long strand inside its body as it does.]
WARRING: As the cyanobacteria get ingested the filament bends and breaks, allowing it to fit inside the rotund little ciliate.
[Closeup of the ciliate ingesting cyanobacteria.]
[WHIRRING, SLURPING ELECTRONIC SOUNDS]
WARRING: This process can take a little time, especially if the filament is particularly long.
[A series of short clips show the ciliate ingesting more and more of the filament.]
WARRING: The ciliate keeps going… and going…and going…and going…and going, until the cyanobacteria are completely swallowed up.
[The ciliate ingests the last of the filament.]
WARRING: Delicious.
[BUBBLY ELECTRONIC MUSIC]
[Back in Central Park, the blue sky shows through the tops of trees. The city skyline outside the park is visible from a bridge. Ducks swim on a pond. Warring walks into frame against greenery, holding a water sample, and speaks to camera.]
WARRING: When I’m out looking at these microbial communities, I often see things that I want to take a closer look at and there’s only so much I can do out in the field with my portable microscope. So, when I see something interesting, I take a sample and that comes with me back to the museum and into the lab.
[Warring puts the sample into her bag and walks out of frame.]
[BUBBLY ELECTRONIC MUSIC]
[Warring enters a laboratory. Text in the lower left reads: “American Museum of Natural History, New York City”. She puts the water sample down on a lab table.]
WARRING: While I’m working with the pond water, I want to keep everything sterile.
[Now wearing black latex gloves, Warring sprays both gloved hands with sterilizing liquid from a bottle and rubs them together. She then sprays and wipes a glass lab jar.]
WARRING: This is because I don’t want microbes that might be growing in the lab or on me to end up growing in my lab cultures.
[Warring brings two now-sterilized glass jars and some other materials over to her workspace, a biosafety cabinet.]
WARRING: Now that the microbes are out of the pond and in the lab, I also need to make sure they have everything they need to survive.
[Warring uses a large pipette to fill small culture dishes with liquid from the two glass jars.]
WARRING: The bottles here contain different types of growth media. Each medium contains vitamins, minerals, and salts that microbes need.
[Warring sits in front of the biosafety cabinet, a metal table enclosed in metal on three sides and glass on the fourth. The glass can be raised and lowered to allow access to the table. The cabinet has a ventilation hood on top.]
WARRING: This big thing is a biosafety cabinet and it’s going to help me keep everything sterile.
I wiped everything down with ethanol before it went into the cabinet, but it also has this wall of air that passes from this vent at the bottom right up the front…
[Warring indicates a vent that runs along the edge of the table underneath the glass plate, blowing air over a person’s hand as they reach into the cabinet.]
WARRING: …and that prevents any microbial spores that might be in the air from traveling though into this cabinet.
At the same time, the cabinet is constantly sucking air up through a vent in the top…
[Warring places her hand inside the cabinet and indicates the vent that is sucking air above the cabinet.]
WARRING: …and that means that if any microbial spores do make it through into the cabinet, they get sucked up into that vent rather than landing on my cultures.
I add a small amount of pond water to liquid medium or spread some out onto an agar plate.
[Warring adds a few drop of the pond water sample to the small culture dishes filled with liquid growth medium, and a few drops to a wide Petrie dish filled with a gelatinous substance.]
WARRING: That agar plate contains growth medium too, but it’s been solidified by the addition of agar—a kind of jelly-like substance that’s produced by certain seaweeds.
[Warring uses a metal instrument to evenly distribute the pond water along the surface of the agar plate.]
WARRING: Some microbes prefer to grow on the solid surface of the agar, while others grow better suspended in the liquid medium.
[Warring picks up the liquid cultures and the agar plate, places them inside a growth chamber that resembles a refrigerator, closes the door to the chamber, and speaks to camera.]
WARRING: I keep those cultures in a growth chamber, the growth chamber maintains the temperature and provides a constant amount of light each day.
[Back under the microscope, small microorganisms move around a helical (spiral-shaped) Dolichospermum colony.]
WARRING: Cyanobacterial blooms can cause real problems, some produce toxins that are lethal to many animals.
I’m interested in the microbes that thrive here, organisms like these flagellates…
[On-screen text identifies a small, bluish, tear-shaped organism as a “flagellate.”]
WARRING: …and this euglena algae…
[On-screen text identifies a circular, yellow-green organism as a “euglena.”]
WARRING: …or this collodictyon…
[On-screen text identifies a circular organism that is brown on the inside of a clear transparent membrane as a “collodictyon.”]
WARRING: …all living among the bloom.
[Bright green microorganisms move frenetically, some as individual cells and some in colonies.]
WARRING: Over the next few weeks some of these microbes will grow in numbers…
[Bright green colonies are now grouped together as they grow.]
WARRING: …until eventually I can isolate and identify individual species from those liquid cultures, and from the agar plate.
[Green cyanobacterial growth is now visible on the surface of the agar plate with the naked eye.]
[Warring takes off her black latex gloves and speaks to camera in front of lab equipment.]
WARRING: I’m hoping that by growing and studying some of these microbes that are present in the cyanobacterial blooms that we’ll learn more about the blooms as communities and that we can understand some of the things that are causing these extremely common phenomena.
[Warring picks up her bag and exits frame. The camera remains in place in the lab while the credits begin to roll.]
WARRING (VO): Even our biggest cities contain microbial ecosystems that are vibrant and complex.
Growing these organisms in the lab helps me to understand just what thrives in this microscopic metropolis.
Museum microbiologist Sally Warring introduces cyanobacteria—some of the most abundant organisms on Earth—that are responsible for a large part of the oxygen in our atmosphere. We'll see them through a microscope, and then follow Warring back to the lab to learn about growing microorganisms outside of the pond.
Watch other episodes from the Pondlife series:
This series was made possible with a grant from Science Sandbox, an initiative of the Simons Foundation, and with the support of the Gordon and Betty Moore Foundation.