Sea Grasses And Microbial Communities: A Metabolomic Analyses
This is a modal window.
The media could not be loaded, either because the server or network failed or because the format is not supported.
Formal Metadata
| Title |
| |
| Alternative Title |
| |
| Author | ||
| License | CC Attribution 3.0 Unported: You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor. | |
| Identifiers | 10.21036/LTPUB10858 (DOI) | |
| Publisher | ||
| Release Date | ||
| Language |
Content Metadata
| Subject Area | ||
| Genre | ||
| Abstract |
|
00:00
Computer animationLecture/ConferenceMeeting/Interview
01:04
Meeting/Interview
01:58
Lecture/ConferenceMeeting/Interview
02:12
Computer animation
03:24
Meeting/Interview
03:34
Computer animation
03:49
Lecture/ConferenceMeeting/Interview
04:09
Computer animation
04:41
Meeting/Interview
04:55
Computer animation
05:21
Lecture/Conference
05:40
Meeting/Interview
06:22
Lecture/ConferenceMeeting/Interview
06:58
Meeting/Interview
Transcript: English(auto-generated)
00:07
So I'm really fascinated by the interaction between seagrass meadows and their microbial communities that lives in their sediments. So what we know about seagrasses is that there are these evolutionary descendants of terrestrial plants.
00:21
And on land we have a really good understanding of how terrestrial plants interact with their microbial communities that are living in their rhizospheres and how these plants sort of recruit these microbial communities to become symbionts. Really much less is known or understood about how seagrasses are doing this in the marine world.
00:40
And so for this research study I was really interested in answering three specific research questions. First, what types of metabolites or small compounds the seagrasses are excreting to their soils or their sediments? Second, can we link these metabolites or the presence of these compounds to the actual plant physiology?
01:00
And third, what is the impact on the sediment microbial communities? So actually to understand how seagrasses are interacting with their microbial communities that are living in the sediments is actually quite a complex question because there are so many different interactions between different microorganisms and between the seagrasses themselves
01:21
that could occur in this space. And so to really understand how seagrasses could be influencing the sediment communities that are present, you really need to understand the physiology of both the seagrasses and their microorganisms themselves. So I first started tackling this project by beginning to go out into the field and exploring the composition of metabolites
01:42
that are occurring underneath the seagrass meadows themselves. And now in order to do this, what I did is I went out into the field settings and I collected pore water, which is basically seawater that's occurring in between the sand grains of the sediments. And I saved it for metabolomic analysis. So when I started this project, there really wasn't a good method available for us
02:02
to actually begin to measure these metabolites in the seawater in such low sample volumes. And so I had to develop a method that would allow us to detect these metabolites in the seawater. What I was able to then go out and do is actually measure the pore water composition of metabolites across many different types of seagrass meadows and across different spatial
02:21
and temporal resolution. So after understanding more about the physiology of the seagrasses and what they could be excreting into the environment, we then needed to understand what the physiology was of the microorganisms that were occurring in this habitat. And so you can really do this with two different approaches. The first is based off of sequencing methods
02:41
where you can collect DNA and RNA for metagenomic and metatranscriptomic analyses. And when you do those types of approaches, you begin to get the genomes of individual bacteria or archaea that are living in these sediments. And then you can begin to understand what it is they're actually doing in that environment. So the second method that you can do
03:02
is to do incubation experiments where you can introduce labeled substrates to these incubations, and then you can monitor for the evolution or the production of 13CO2. And when you do this, you get an insight into how quickly the microorganisms are using the labeled substrate over time. And that gives you some insight
03:20
into the actual physiology of the microbes that are present. So the first thing that we found when we started to go and explore the metabolites that are occurring underneath these seagrass meadows worldwide was that there's a lot of sugar that is present there, and specifically in the form of sucrose.
03:40
Having high concentrations of sucrose and actually the micromolar levels is quite unusual in the environment because microorganisms like to eat sugar. Sugar is a common thing that we even put in our coffee in the morning, for example, and that microorganisms across different environments will use regularly and rapidly in their metabolism. So to understand the microbial communities
04:02
that are present, I first wanted to know, is the community underneath the meadow specific to the meadow itself? And what I was able to find and show is that the microorganisms that are occurring underneath the meadow are different. The community is different than the microorganisms that are occurring outside the meadow. They have the genes they need to use sucrose in their metabolism.
04:22
However, very strangely, when we look at the transcripts or the expression of those genes, what we find is that they're not expressing those genes. So they're not making the proteins needed to break down sucrose in their metabolism. So in order to understand this dichotomy between what we see in the genomes and the expression of these genes,
04:42
we can use our sediment incubation experiments to test to see if there are specific conditions where the microorganisms can use sucrose versus the conditions that we see in the meadow where we know that they're not using the sucrose. And what I was able to show with these incubations is that under oxic conditions
05:01
and flush seawater, what we find is that the microorganisms actually have the ability to use these sucrose in their metabolism. But when we take away that oxygen and we add back the inhibitory compounds that we also measure in the meadow, what we find is that the microbial communities no longer have that ability to use sucrose.
05:21
And so what this all comes together with coupling the presence of the sucrose in the meadow, the plant physiology and the biochemical conditions that are in the meadow is that we see this accumulation of sucrose over time and is why we can measure such high concentrations of it in the environment.
05:42
So seagrasses are these really important ecosystems to global oceans. And so if you think about seagrasses, they only cover about 0.1% of the ocean surface area. However, despite their low abundance in the ocean, they're actually responsible
06:01
for 10% of the burial of organic carbon in marine systems. So if you think about it, that means that they have this disproportionate ability to bury carbon over long periods of time. And they typically do this by burial through their tissues, but also through deposition of organic carbon into the environment or into their sediments.
06:22
And so we know based off of the terrestrial systems that microbial communities play this intimate role in facilitating carbon burial on land. We also need to know how those communities play this important role of facilitating carbon burial in the ocean and specifically associated with seagrasses.
06:41
Our work really sheds light into this by describing processes that allow seagrasses to interact with the microbial communities that are present in the sediments and provides important insights into how those interactions develop and how they persist over time.
07:01
The amazing thing about this study is that it's opened up so many different avenues of research that I'm really excited to explore. However, there are three questions that I really want to focus in on. First of all, what other types of compounds are these seagrasses excreting into their environment? And second, how do these compounds interact
07:22
with the microbial communities that are there? So are they excreting other types of metabolites besides sucrose and are those metabolites then attracting other types of microorganisms that could benefit the physiology of the seagrasses? And the third thing that I'm really interested in understanding is how changing climatic conditions
07:41
is altering these relationships. So as we see changes in land use that lead to eutrophication of the environment or changes in climate change, how do they impact how seagrasses and their microbial communities actually interact and what does that mean for the health of these ecosystems?
Recommendations
Series of 11 media