This course was produced by the Algae Technology Educational Consortium and UC San Diego with funding from the Algae Foundation, the National Renewable Energy Lab, and the U.S. Department of Energy. Algae are an extremely diverse group of organisms that can be found in almost every ecosystem on the planet, and they play an essential role for life on earth. They are little bio-factories that use the process of photosynthesis to create chemical compounds that we can utilize for food, feed, medicine, and even energy. We’ve brought together some of foremost algae experts from industry and academia to teach you the fundamentals of algae. This course will cover what algae are, why they are important, and why we are interested in them for both their environmental benefit, as well as their use for products. You will also explore the vast diversity of algae including the characteristics and applications of some of the main types of algae that are in commercial use today. Later you will learn about algal ecology and how interactions with environment, including pests and predators, affect algal productivity. And finally you will examine the processes of algae bio-manufacturing including production processes, as well as some of the products, benefits, and challenges that impact our ability to make commercially viable products from algae.
What are Algae?
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Из курса от партнера University of California San Diego
Introduction to Algae
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Algae Basics
This section will cover what algae are, how they've evolved, and how they've transformed our planet. We will also go over how humans have used algae throughout history.
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Dr. Stephen MayfieldProfessor of Molecular Biology
University of California San Diego
Ira "Ike" LevineProfessor, Natural and Applied Sciences
University of Southern Maine
Hi, I'm Stephen Mayfield,
Professor of Biology at the University of California San Diego,
and Director of the California Center for Algae Biotechnology
so Today's talk is What are Algae?
So there's many ways to define this,
and I think perhaps the easiest way is to start with a pretty simple definition.
So algae are aquatic organisms that contain chlorophyll,
and carry on photosynthesis.
As you'll see during this class,
there are lots of other ways we're going to define these
because they are a very diverse set of organisms,
but that's probably the simplest one that we can start with.
Second of all, there are very diverse organisms.
They're ubiquitously found on the planet.
Many of them are micro-algae,
which means too small to see with your naked eye.
You'll still see the green color or the red color of them,
but you won't see individual cells.
There are also macro-algae.
These are the large algae that you can see their structures that look
quite a bit like sort of plants in water, aquatic plants.
Right? But in fact, they are algae.
And some of these you'll recognize as the kelps and the seaweeds.
It's also important to note that algae are by definition actually eukaryotes.
That means they are eukaryotic cells,
which have a nucleus and a separate chloroplast.
This distinguishes them from cyanobacteria,
which are photosynthetic bacteria,
but for this class,
we're going to call algae to include
both the true eukaryotic algae as well as the cyanobacteria.
So as I said, they carry on photosynthesis.
So photosynthesis is the biological conversion of
sunlight energy plus carbon dioxide into chemical energy,
and is clearly one of the most important reactions on the planet.
So what happens in photosynthesis is we take
sunlight energy and CO2 along with some nutrients,
and this goes on inside of every algae, every cyanobacteria,
and every plant, and then what comes out of that are primary sugars.
And then those sugars are quickly converted to carbohydrates, proteins, and lipids.
And you'll obviously recognize carbohydrates and proteins and lipids as food,
but those are also the building blocks for everything we make in biology.
So that reaction which is carried on by
algae is just fundamental to everything on the planet.
And we'll talk about that a lot in this class.
So as I said, algae are extremely diverse.
This is a tree of life,
and every one of those colored boxes is a different family of algae,
different division of algae.
Right? So they cover every single aspect,
with cyanobacteria down there in the bottom left hand corner.
Green algae in the bottom right.
And many other of the different brown algaes in the upper left hand corner.
Just to point out how diverse they are,
the orange colored box around fungi and the red colored box around animals,
that is all animals and all fungi.
So every animal on the planet, whether it's a human,
or a blue whale, or an insect,
every single one of those is contained in
that one little branch compared to look at the extensive branching of algae.
They are everywhere, and they have been around on this planet for billions of years.
With that diversity in the branch of life,
also comes diversity in genetics,
and diversity in the set of products they make,
and we'll talk about that as the class goes on.
So let's look at a basic algae cell.
So as I said, we're going to call cyanobacteria and algae together,
we're going to group all of these in.
So if you look at a cyanobacteria,
that is the simplest algae cell.
And because they carry on photosynthesis,
there's one thing that you will always see on those,
and that is thylakoid membranes.
So those are the membranes that contain
the protein complexes that make up what's called the light reactions of photosynthesis,
so that is the light harvesting apparatus.
In addition to the light harvesting apparatus,
you have to have water soluble stroma,
and that carries on the dark reactions or the carbon fixing part of photosynthesis.
In addition, you'll also see some storage components inside of
a cyanobacteria quite often those are a glycol,
a carbohydrate storage form.
If you look at the other cell, an algae cell as I said before,
they're eukaryotic cells, so they're a bit more complex.
They have a nucleus.
They also have a chloroplast,
and that chloroplast looks an awful lot like a cyanobacteria.
In fact as we'll describe later,
chloroplast come from cyanobacteria.
It was actually a eukaryotic cell engulfing
a cyanobacteria that resulted in an algae cell.
This happens to be a picture of a green algae called Chlamydomonas,
it has something called a pyrenoid.
That pyrenoid is a subcellular structure that contains the carbon fixing enzymes,
and it's a way to concentrate CO2.
You can also see on this starch granules accumulating,
quite often lipid bodies.
They'll have a cell wall and then in this case, they have flagella.
So much more complex organisms, much larger genomes,
but they carry on the same essential function, which is photosynthesis.
As I said, algae are found in every environment.
They are virtually in every part of this planet.
What's shown here in the upper left hand corner is snow,
and that happens to be a pink algae.
That's also a Chlamydomonas,
and that grows quite well even at those very low temperatures.
In the upper right hand corner is a small pond or a still lake,
and that one you will recognize being filled with green algae,
very common to see this.
Almost any pond, any river that has nutrients in it,
nitrogen and phosphate, there will be an algae bloom in it.
The bottom left hand corner is an ocean algae bloom that happens to be a red algae.
Quite often you'll see large blooms on the ocean when you get an upwelling of nutrients.
That's what's limiting out in the ocean water,
and then in the bottom right hand corner,
you see some of the macro-algae or the kelp.
And this is simply to sort of show number one,
the diversity in structures,
the diversity in colours,
and then also the diversity in environments that they grow in.
So they are everywhere on this planet.
In addition to the diversity in the environments they grow in,
they also have a great physiology diversity, physiological diversity.
Right? Now, what does that mean?
Well, here's just a few examples.
In the upper left hand corner is a green algae called Haematococcus.
And when that algae runs out of food,
runs out of nitrogen,
it goes into a storage form and accumulates a red pigment.
So what's showing here is this red pigment,
astaxanthin, accumulating in the cells.
To the right of that is another green algae called Botryococcus,
and that algae happens to secrete an isoprenoid called botryococcene.
So it is a lipid that it secretes out into the environment.
On the bottom left hand corner are one of the diatoms,
one of the brown algaes.
And diatoms, you may know,
have these beautiful cell wall structures made of silicate,
and that's simply to show the intricacies of that,
and also to show the diversity.
Again, there's a red algae bloom in
the bottom right hand corner that happens to be a toxic algae.
We'll talk a little bit about that as the class goes on.
Right? But again, just showing this wonderful diversity of
physiology reflected here in
the pigments that they make or the structures that they make,
as well as the great genetic diversity within these.
And then finally on the right hand side is simply one of the macroalgaes,
a kelp growing out in the ocean.
And again, very different in structure,
very different in colour,
very different in the compounds that it produces,
and the compounds that it accumulates.
So simple demonstrations of the great diversity of these things.
Now, as I said, algae are a fundamental part of the of the environment.
They're ecologically important, and they serve as the base of the aquatic food chain.
This is true in both the ocean systems and in true in freshwater.
So as I said before, they carry on
photosynthesis so that means they're primary producers.
That means as long as there is a little bit of
nutrients in the water, little bit of nitrogen,
a little bit of phosphate,
sunlight and CO2, you will get an algae bloom,
and those algae will start to grow.
Once those algae grow,
they're quickly eaten by small sea animals.
Zooplankton, and then those zooplankton are eaten by small fish,
and then those fish by larger fish.
And here in this diagram we show sharks as being the top of the food chain,
but you'll understand that that could also be humans, it could be seals,
it could be anything that's at the top of the food chain,
showing the fundamental importance.
You do not have any aquatic system if you don't have algae in it.
And then on the right is simply a diagram showing that
the exact same thing happens in freshwater.
In this case again,
you get algae growing in the water.
Those are then consumed by small animals,
then by larger fish,
and then very large fish,
and here we show the top of the food chain being a bird eating the fish,
but again, just a fundamental part of the food chain.
Without algae, we would not have life on this planet.
So we will talk about all of those things,
and many other of the fantastic attributes of algae throughout this class.
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