Este curso destina-se a introduzir os alunos para as questões de energia no século 21 - incluindo alimentos e combustíveis - que estão inseparavelmente ligados - e vai discutir a produção e utilização de energia a partir de perspectivas da biologia, engenharia, economia, ciência climática e das ciências sociais. Este curso irá cobrir a atual produção e utilização de energia, bem como as consequências dessa utilização, examinando as reservas de energia fóssil finita, como alimentos e energia estão ligados, os impactos sobre o ambiente e o clima e os impactos sociais e econômicos da nossa atual produção e uso da energia e dos alimentos. Após as palestras introdutórias, vamos examinar as áreas emergentes da energia sustentável, produção de combustível e alimentos, enfatizando a importância do desenvolvimento de métodos de produção energeticamente eficientes e sustentáveis, e como estas novas tecnologias podem contribuir para substituir os suprimentos decrescentes de combustíveis fósseis e reduzir as consequências da emissão de dióxido de carbono para o ambiente. Este curso também irá abranger a importância de criar um futuro energético sustentável para todas as sociedades, incluindo as do mundo em desenvolvimento. As palestras serão preparados e entregues pelos principais professores da UC San Diego e Scripps Institution of Oceanography e profissionais da indústria em todas estas áreas de especialização.
Cyanobacteria Part 2
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Do curso por University of California San Diego
O futuro da energia
411 classificações
Na lição
Algae Biofuel
Examines different algae used for biofuel production including cyanobacteria, diatoms, and green algae. It looks at how these organisms are different and why they are used to produce biofuels and bio-products. Additionally, the module covers the different tools and technologies used in research and production including bio-prospecting, genetics, synthetic biology, and metabolic engineering.
Conheça os instrutores
Dr. Stephen MayfieldProfessor of Molecular Biology
University of California San Diego
[MUSIC]
Susan, thanks so much for the great introduction.
I think I have a few questions that our audience will, will be interested in.
And and you can help us with those.
So, one of the things is you showed this great diversity
of cyanobacteria that, that, they grow you know, in the arctic.
And they grow in thermal hot springs.
How does that diversity help?
when, when we think about bio-fuel production
or production of anything used in cyanobacteria?
>> Whenever you have diversity of either the cell physiology, the ecology, where it
lives, what that means is that there
are different enzymes there to make different products.
Because an organism has to be adapted well to its environment.
And also the morphology is going to be different.
So a cell that is filamentous is going to be
expressing genes that you don't have in, in, well,
a strain that's filamentous is going to be, its cells
are going to be expressing genes that you don't have in.
>> Yeah.
>> So the unicellular species.
But if you think about it, an organism that lives in, for example, very high
salt conditions is going to have enzymes that
are, have evolved to work in that environment.
And as we start sampling different
environments we're also just discovering new genes.
So genes that we didn't even know about and that
means chemistries and enzymes that we didn't already know about.
And so whenever we make a, we talk about how important the diversity is, that's
because we know that the diversity of raw
material that we can work with to engineer.
>> So, genetic diversity as well as physiological diversity.
>> Exactly.
>> So you talk also about having a model system versus having a production strain.
In, in your mind, what are the biggest differences between those two?
>> Probably the biggest difference is that the model organisms were
chosen in many cases decades ago for particular properties
that were of interests to the scientists who were bringing
them into the lab and starting to work with them.
And decades ago we weren't thinking about how well something grows
out in a pond to be useful as a biofuel strain.
Very often, the organisms were chosen because they
did something that the scientists wanted to study.
For example, to spe, differentiate specialized cells to fix nitrogen, or
because they were easy to work with genetically and traits,
there different traits then aqua culture traits and large scale growth traits.
And so if we think about what we want to do now, it's important to find organisms
that are going to work really well at production
scale and then make models out of those
and what we mean by model is a strain that there is that there is enough
agreement and enough agreement that goes in to
work with that strain and to understand it Well.
And if we go back really decades to when people
were studying cyanobacteria, every paper was on some different strain.
>> Right.
>> And so that was great.
because the diversity was sampled.
But it, there wasn't enough effort to make real progress on any one strain.
>> That's right.
>> And then the models went the other direction to where
we really kind of know a lot about a few strains.
And now we say, but wait a minute, those arent the
ones that have the properties we want to focus on for biofuels.
>> That's right.
They're just like agricultural, we'll pick a few cyanobacterial
>> Right.
>> Strains that we'll grow at very large.
>> Exactly.
>> So one of the things you talked about was this genetic diversity.
So, if we look at a cyanobacteria genome, how big and complex are they
and how are we going to introduce genes into the production strains that we want?
>> They really vary a lot, so the smallest genomes are about 2 million base pairs,
and that's smaller than the genome of E
coli which is the most commonly genetically engineered strain.
And then there are others that are up around six, eight,
or even 10 million base pairs which is a much bigger genome.
And one, you find, you can't really say that a
bigger genome means this or that except that typically for the
strains that have a greater metabolic diversity they are a great
more unusual metabolic capabilities, and more tricks that they can do.
>> Mm-hm.
>> They're going to have bigger genomes.
Now in terms of introducing genes, it's not just that if you
have a bigger genome to begin with you can introduce more genes.
The small organisms can in fact sometimes take very big transfers of pathways,
and I think that good examples of that from, from genetic re,
genetic history biotechnology history is that E coli, is a, you know reasonably
small genome organism and a lot has been done with engineering E coli.
>> Right.
So, I know in terrestrial agriculture one of the big concerns, that
I mean the things that farmers fight all the time are crop protection.
How do I keep pests and pathogens from
eating my crop or fungus from taking it down.
Will that be the same in a biofield crop of cyanobacteria?
>> Oh absolutely, so anything that an organism is making that we find valuable.
It's probably going to have a good source of carbon in it.
And carbon is what organisms use as the
skeleton of everything that they need for their cells.
Which means that if there's something out there that
is alive something else is going to eat it.
>> That so.
>> It pretty much comes down to that.
And so we do have to worry about invading organisms of a couple of sorts.
Either that will compete for nutrients and compete for resources,
or that will actually consume and otherwise kill the crop.
>> So weeds versus predators or pathogens.
>> Exactly.
And there are many of both kinds that are out
there constantly moving around and settling anywhere including in the ponds.
>> So what, are some of, some of the strategies that your
group is, is thinking about, in, in order to get crop protection [UNKNOWN].
>> Well for different kinds of, of algal crops there
are different kind of characteristically notorious ponds, and for sign
of bacteria if you talk to people that are raising
these ponds they'll tell you that amoebae are a big problem.
Now, there are lots of different kinds of amoebae,
but knowing that amoebae problem, one of the things that
we've done is, along with our collaborators at the
Scripps Institution of Oceanography, we've been identifying we've been identifying
amoebae that specifically eat the cyanobacteria that we use as a
model, for which we do have a lot of genetic tools.
And once we had that predictor prey system set up we could, we could screen an entire
library of mutants which means a collection of
mutants were each one is missing a different gene
and we were able to find that we
could knock out a particular pathway that affects the
cell surface and the meeting no longer then
this particular amoeba anyway no longer eats our bacterium.
So that, that really gave us a first clue, of one of the things that we can do to
make cells resistant to amoeba put some kind, some kind of a mask on them.
>> Mm-hm.
>> So they no longer look so tasty and there are probably many other ways
but, we, once we have the question we can go in and ask it and.
>> So it sounds though, that crop
protection in algal biofuels would be similar.
>> Right.
>> You know, not identical, but similar to
the strategies that we've employed for terrestrial crops.
>> Right.
Which is, you have to identify the pest that you're concerned
about and try to find a solution that works with that pest.
And then you have to go back and ask, well, how general is it?
And does this protect from other pests?
Or do we need some other strategy for other pests?
>> Okay, I know one of the other concerns in, in, any biofuel, in any crop.
And especially if we're going to use crops like, like cyanobacterial for fuels.
Are both the water utilization as well as the nutrient utilization.
Now you mentioned that nitrogen can be fixed by these,
but what are some of the other nutrients and, and
what are some of the other strategies that we might
use to, to make sure that we're efficiently using those?
>> Well, phosphorus is another one that's
quite important in biological systems and phosphorus is
an issue really for all agriculture and
will certainly be an issue for algal crops.
And recycling the nutrients is an important
avenue going forward, to make sure that
the phosphorous in the water gets re-utilized,
that any of the biological material, the
spent biological material that the that the fuel molecules have been removed from,
that, that gets put back into the system so that we can recycle those nutrients.
>> And in the nitrogen-fixing then, how is it that cyanobacteria can
do this where most terrestrial plants and certainly eukaryotic green algae cannot?
>> There is, cyanobacteria aren't the only organisms
that can fix nitrogen, but most organisms don't and
the ones that we do know of are
prokaryotic, although sometimes they live in symbiosis with eukaryotes.
>> Right.
>> And nitrogen fixation requires really a lot of genes to make a lot of, not only
a lot of enzymes, but to specialize the cells
to be able to keep the oxygen tension low.
So the enzyme that's used to fix nitrogen in
the air into ammonia is very sensitive to oxygen.
>> Right.
>> And one of the things that we see in these
species that can, is that they have a number of different
strategies for having their, their, their nitrogenous enzyme active in some
sort of an intracellular environment where the oxygen tension's very low.
>> Right.
Hence, the specialized cells that you showed in that one.
>> Exactly.
>> Okay so, you know you, we, we talked about the potential for biofuels.
You showed in one of your early slides
that cyanobacteria can be eaten, actually, as a food.
So obviously we can make food and fuel out of, out of cyanobacteria.
What are the other potentials that you see in this that sort
of excite you about the future and, and where the field may go?
>> Well, I think that it's very important that we learn
to replace petroleum as a source for all kinds of chemicals.
So it's not only a matter of fue, foo, excuse me fuel or a food, or or
medicines but also just a lot of the every day things that we use that are currently
made of plastics and so I think as a source of the carbon skeletons that can be
used for a lot of the materials and the
structures that we need in our every day life.
The ability to use algae both cyanobacteria and eukaryotic algae as a
source of the building blocks of those materials would be very important.
>> Okay, great.
Well thanks very much for the introduction to
cyanobacteria and best of luck to your research.
>> Thank you.
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