Tag Archives: Microbiology

Diving into the Unknown: Exploring the Role of Viruses in Coral Reef Health

When you think of a coral reef, what do you picture? Perhaps you imagine colorful branching structures jutting out of rock and the sea floor, with flourishing communities of fish swimming about. Or if you’ve been paying attention to news about global warming for the past decade or two, maybe you picture desolate expanses of bleached corals, their bone-like structures eerily reminiscent of a mass graveyard.

What you might not picture is a zoomed-in view of the coral ecosystem: the multitude of bacteria, fungi, viruses, and algae that occupy the intricate crevices of every coral. While corals are indeed animals in their own right, they belong to a complex symbiotic relationship with these microorganisms: the algae, which are more specifically dinoflagellates, provide energy to the coral through the process of photosynthesis. Bacteria occupying the mucus layers cycle nutrients and play a role in defense against pathogen invasion through the production of antimicrobial peptides.

One lesser-known member of this community, or the coral ‘holobiont’ as it is called, are the viruses. It’s probable that, like other members of the holobiont, they contribute to the health of the coral in some way, but this role is as of yet unclear. Our guest this week is Emily Schmeltzer, a fifth year PhD student in the Vega Thurber lab in the Department of Microbiology, and these elusive viruses are exactly what she is trying to uncover.

*Emily Schmeltzer*, *PhD candidate in Rebecca Vega-Thurber’s lab, takes a sample of a coral*

“We don’t know a ton about viruses on coral reefs,” says Schmeltzer. “ We know that some probably cause disease or mortality through infections, but we don’t really know exactly what a lot of them are doing, because marine viral ecology is such a relatively new field,” she explains.

It’s not surprising: viruses, while the most abundant and diverse entity on earth, are incredibly tiny and difficult to detect in environments where other organisms also thrive. Part of the challenge is that they have no universally conserved genes: that is, no easy way to tell the genes from viruses apart from the genes of other organisms. When studying bacteria, a gene called the 16S rRNA gene can be used as a sort of ‘name tag’ – every bacteria has this gene, whereas other organisms do not. There’s no such thing for viruses, making them difficult to study if you don’t already know what you’re looking for.

Schmeltzer is studying the viruses that live on corals and their response to climate change. To do this, her PhD research has involved a massive spatiotemporal study (spatio = across different locations, temporal = across multiple time points) looking at nearly 400 individual coral colonies of three different species over 3 years. All of these colonies are off the coast of the Moorea, a small island in French Polynesia in the South Pacific. The ultimate goal of the project is to contribute to the ongoing data collection for the Moorea Coral Reef Long Term Ecological Research project, and to characterize virus community diversity and potential function in the health of these corals.

Studying coral reefs is a big leap for Schmeltzer, who hails from the land-locked deserts of New Mexico. She was always interested in biology, which she attributes to her dad bringing home dead scorpions to look at together when she was a child. Arthropods ultimately ended up becoming her first research subjects: as an undergraduate at the University of New Mexico, she worked in an insect and spider taxonomy lab, before pivoting to working on West Nile virus.

So how did this insect-loving desert-dweller end up studying viruses that live on corals in the ocean? To learn more about Schmeltzer’s career trajectory, her love of corals, and the challenges of viral research, tune in to Inspiration Dissemination this Sunday, April 2nd at 7 PM. Listen live at 88.7 FM or on the live stream, or catch the episode after the show wherever you get your podcasts!

Stressed out corals

Coral reef ecosystems offer a multitude of benefits, ranging from coastline protection from storms and erosion to a source of food through fishing or harvest. In fact, it is estimated that over half a billion people depend on reefs for food, income, and/or protection. However, coral reefs face many threats in our rapidly changing world. Climate change and nutrient input due to run-off from land are two stressors that can affect coral health. How exactly do these stressors impact corals? This week’s guest Alex Vompe is trying to figure that out!

Alex is a 4^th year PhD candidate in the Department of Microbiology at OSU, where he is co-advised by Dr. Becky Vega-Thurber and Dr. Tom Sharpton. The goal of Alex’s research is to understand how coral microbe communities change over time and across various sources of stress. While the microbial communities of different coral species can differ, typically under normal, non-stressed conditions, they look quite similar. However, once exposed to a stressor, changes start to arise in the microbial community between different coral species, which can have different outcomes for the coral host. This pattern has been coined the ‘Anna Karenina principle’ whereby all happy corals are alike, however as soon as things start to go wrong, corals suffer differently.

Alex is testing how this Anna Karenina principle plays out for three different coral species (Acropora retusa, Pocillopora verrucosa [also known as cauliflower coral], Porites lobata [also known as lobe coral]) in the tropical Pacific Ocean. The stressors that Alex is investigating are reduction in herbivory and introduction of fertilizer. A big source of stress for reefs is when fish populations are low, which results in a lack of grazing by fish on macroalgae. In extreme situations, macroalgae can overgrow a coral reef completely and outcompete it for light and resources. Fertilizers contain a whole host of nutrients with the intent of increasing plant growth and production on land. However, these fertilizers run-off from land into aquatic ecosystems which can often be problematic for aquatic flora and fauna.

How is Alex testing the effects of these stressors on the corals? He is achieving this both in-situ and in the lab. Alex and his lab conduct field work on coral reefs off the island of Moorea in French Polynesia. Here, they have set up experimental apparatus in the ocean on coral reefs (via scuba diving!) to simulate the effects of reduced herbivory and fertilizer introduction. This field work is conducted three times a year. When not under the water surface, Alex sets up aquaria experiments on land in Moorea using coral fragments, which he has been able to grow in order to investigate the microbial communities more closely. These samples then get processed in the lab at OSU for genomic analysis and Alex uses bioinformatics to investigate the coral microbiome dynamics.

Curious to know more about Alex’s research? Listen live on Sunday, October 23, 2022 at 7 PM on KBVR 88.7FM. Missed the live show? You can download the episode on our Podcast Pages! Also, feel free to follow Alex on Twitter (@AVompe) and Instagram (@vompedomp) to learn more about him and his research.

Microbial and biochemical community dynamics in low-oxygen Oregon waters

Much like Oregon’s forests experience wildfire seasons, the waters off the Oregon coast experience what are called “hypoxia seasons”. During these periods, which occur in the summer, northern winds bring nutrient-rich water to the Eastern Current Boundary off the Oregon Coast. While that might sound like a good thing, the upwells bring a bloom of microscopic organisms such as phytoplankton that consume these nutrients and then die off. As they die off, they sink and are then decomposed by marine microorganisms. This process of decomposition removes oxygen from the water, creating what’s called an oxygen minimum zone, or OMZs. These OMZs can span thousands of square miles. While mobile organisms such as fish can escape these areas and relocate, place-bound creatures such as crabs and bottom-dwelling fish can perish in these low oxygen zones. While these hypoxia seasons can occur due to natural phenomena, stratification of the water column due to other factors such as climate change can increase the frequency or severity of these seasons.

2021 was one of the worst years on record for hypoxic waters off the Western coast of the United States. A major contributing factor was the extremely early start to the upwelling triggered by strong winds. Measurements of dissolved oxygen and ocean acidity were high enough to be consistent with conditions that can lead to dead zones, and this is exactly what happened. Massive die-offs of crabs are concerning as the harvesting of Dungeness crab is one of the most lucrative fishing industries in the state. Other species and organisms move into shallower waters, disturbing the delicate balance of the coastal ecosystems. From the smallest microbe to the largest whale, almost every part of the coast can be affected by hypoxia season.

Our guest this week is Sarah Wolf, a fourth year PhD candidate in the Department of Microbiology here at Oregon State. Sarah, who is co-advised by Dr. Steve Giovannoni and Dr. Francis Chan, studies how microbes operate in these OMZs. Her work centers around microbial physiology and enzyme kinetics, and how these things change over time and in varying oxygen concentrations. To do this, she spent her second year developing a mesocosm, which is a closed environment that allows for the study of a natural environment, which replicates conditions found in low oxygen environments.

*Sarah Wolf, a fourth year PhD Candidate in the department of Microbiology, in her lab*

Her experiments involve hauling hundreds of liters of ocean water from the Oregon coast back to her lab in Nash Hall, where she filters and portions it into different jugs hooked up to a controlled gas delivery system which allows her to precisely control the concentration of oxygen in the mesocosm. Over a period of four months Sarah samples the water in these jugs to look at the microbial composition, carbon levels, oxygen respiration rates, cell counts, and other measures of the biological and chemical dynamics occurring in low oxygen. Organic matter can get transformed by different microorganisms that “eat” different pieces through the use of enzymes, but many enzymes which can break down large, complex molecules require oxygen, and in low oxygen conditions, this can be a problem for the breakdown and accumulation of organic matter. This is the kind of phenomenon that Sarah is studying in these mesocosms, which her lab affectionately refers to as the “Data Machine”.

Sarah’s journey into science has been a little nontraditional. A first generation college student, she started out her education as a political science major at Montana State before moving to the University of the Virgin Islands for a semester abroad. At the time she wasn’t really sure how to get into research or science as a career. During this semester her interest in microbiology was sparked during an environmental science course which led to her first research experience, studying water quality in St. Thomas. This experience resulted in an award-winning poster at a conference, and prompted Sarah to change her major to Microbiology and transfer to California State University Los Angeles. Her second research experience was very different – an internship at NASA’s Jet Propulsion Laboratory studying cleanroom microbiology, which resulted in a publication identifying two novel species of Bacillus isolated from the Kennedy Space Center. Ultimately Sarah’s journey brought her here to Oregon State, which she was drawn to because of its strong marine microbiology research program.

But Sarah’s passion for science doesn’t stop at the lab: during the Covid-19 pandemic, she began creating and teaching lessons for children stuck at home. During this time she taught over 60 kids remotely, with lessons about microbes ranging from marine microbiology to astrobiology and even how to create your own sourdough starter at home. Eventually she compiled these lessons onto her website where parents and teachers alike can download them for use in classrooms and at home. She also began reviewing children’s science books on her Instagram page (@scientist.sarahwolf), and inviting experts in different fields to participate in livestreams about books relating to their topics. A practicing Catholic, she also shares thoughts and resources about religion and science, especially topics surrounding climate science. With around 12k followers, Sarah’s outreach on Instagram has certainly found its audience, and will only continue to grow.

If you’re curious about microbes in low oxygen conditions, what it’s like to be a science educator and social media influencer, or want to hear more about Sarah’s journey in her own words, tune in at 7 PM on March 13th to catch the live episode at 7 PM PST on 88.7 FM Corvallis, online at https://kbvrfm.orangemedianetwork.com – or you can catch this episode after the show airs wherever you get your podcasts!

Trusting Your Gut: Lessons in molecular neuroscience and mental health

The bacteria in your gut can talk to your brain.

No, really.

It might sound like science fiction, but you’ve probably heard the phrase ‘gut-brain axis’ used in recent years to describe this phenomenon. What we call the “gut” actually refers to the small and large intestines, where a collection of microorganisms known as the gut microbiome reside. In addition to the microbes that inhabit it, your gut contains around 500 million neurons, which connect to your brain through bidirectional nerves – the biggest of which is the vagus nerve. Bacteria might be able to interact with specialized sensory cells within the gut lining and trigger neuronal firing from the gut to the brain.

Our guest this week is Caroline Hernández, a PhD student in the Maude David Lab in the Department of Microbiology, and she is studying exactly this phenomenon. While the idea that the gut and the brain are connected is not exactly new (ever heard the phrase “a gut feeling” or felt “butterflies” in your gut when you’re nervous?), there still isn’t much known about how exactly this works on a molecular level. This is what Caroline’s work aims to untangle, using an in vitro (which means outside of a living organism – in this case, cells in a petri dish) approach: if you could grow both the sensory gut cells and neurons in the same petri dish, and then expose them to gut bacteria, what could you observe about their interactions?

*Caroline Hernández in her lab at Oregon State, using a stereo microscope to identify anatomical structures in a mouse before dissecting out a nerve bundle*

The answer to this question could tell us a lot about how the gut-brain axis works on a molecular level, and could help researchers understand the mechanisms by which the gut microbiome can possibly modulate behavior, mood, learning, and cognition. This could have important implications down the line for how we conceptualize and potentially treat mood and behavioral disorders. Some mouse studies have already shown that mice treated with the probiotic Lactobacillus rhamnosus display reduced anxiety-like and depressive behaviors, for example – but exactly how this works isn’t really clear.

The challenges of in vitro research

Before these mechanisms can really be untangled, there are several challenges that Caroline is working on solving. The biggest one is just getting the cells to grow at all: Caroline and her team must first carefully extract specific gut sensory tissue and a specific ganglion (which is a blob of neurons) from mice, a delicate process that requires the use of specialized tools and equipment. Once they’ve verified that they have the correct anatomy, the tissues are moved into media, a liquid that contains specialized nutrients to help provide the cells with the growth factors they need to stay alive. Because this is very cutting-edge research, Caroline’s team is among the first in the world to attempt this technique – meaning there is a lot of trial and error and not a great amount of resources out there to help. There have been a number of hurdles along the way, but Caroline is no stranger to meeting challenges head-on and overcoming them with incredible resilience.

From art interactions to microbial interactions

Her journey into science started in a somewhat unexpected way: Caroline began her undergraduate career as a studio art major in community college. Her art was focused on interactivity and she was especially interested in how the person perceiving the art could interact with and explore it. Eventually she decided that while she was quite skilled at it, art was not the career path she wanted to pursue, so she switched into science, where she began her Bachelors of Science in molecular and cellular biology at the University of Illinois in Urbana Champaign.

During her undergraduate degree, a mental health crisis prompted Caroline to file for a medical withdrawal from her program. The break was much needed and allowed her to focus on taking care of herself and her health before returning to the rigorous and intense program three years later. Caroline is now a strong supporter of mental health resource awareness – in this episode of Inspiration Dissemination she will describe some of the challenges and barriers she faced when returning to finish her degree, and some of the pushback she faced when deciding to pursue a PhD.

“Not everyone was supportive,” she says. “I didn’t receive great encouragement from some of my advisors.”

Where she did find support and community was in her undergraduate research lab. Her work in this lab on the effects of diet and the microbiome on human health gave her the confidence to pursue graduate school, demonstrating that she was more than capable of engaging in independent research. In particular Caroline recalls her mentor Leila Shinn, a PhD student at the time in that lab, who had a profound impact on her decision to apply to graduate programs.

Tune in on Feb 27th to hear the rest of Caroline’s story and what brought her to Oregon State in particular. You can listen live at 7 PM PST on 88.7 FM Corvallis, online at https://kbvrfm.orangemedianetwork.com, or you can catch the episode after the show airs wherever you get your podcasts.

If you are an undergraduate student or graduate student at Oregon State University and are experiencing mental health struggles, you’re not alone and there are resources to help. CAPS offers crisis counseling services as well as individual therapy and support and skill-building groups.

A blade of seagrass is a powerful thing

Even though seagrasses occupy less than 0.2% of the world’s oceans, they account for more than 10% of all carbon trapped in the sea. In a world and time where we are producing more carbon than we should be and can manage, making sure that seagrasses are healthy and abundant is extremely pertinent. Winni Wang is one such seagrass scientist working to understand the biology of seagrasses and what threatens them.

Winni is a 5^th year PhD candidate in the Department of Microbiology working with Dr. Ryan Mueller. Winni specializes in studying the microbiome of different plants, which for her PhD happens to be seagrasses. The microbiome is the community of microorganisms in a particular environment, and therefore it is found on all living things. By studying the microbiome on different seagrasses, Winni hopes to determine how anthropogenic (human-induced) stressors affect seagrass plants as a whole through changes in the microbiome.

If you’re like me and you love marine megafauna, then when thinking about seagrass beds you most likely are picturing a big manatee slowly grazing on seagrass in tropical, warm waters. Well, then you might be surprised to know that seagrasses don’t only occur in warm, tropical waters. In fact, there are over 60 species of seagrass worldwide and they occur in all kinds of habitats and climates. As a matter of fact, there is a species of seagrass right off of our coast here in Oregon, in Yaquina Bay, which is one of Winni’s study sites for her thesis research.

Winni with the experimental tanks at HMSC.

Her work in Yaquina Bay relates to understanding how seagrasses are affected by eutrophication. Eutrophication occurs when an excessive amount of nutrients enters an aquatic environment, often due to land run-off, which in extreme cases can lead to severe oxygen depletion in those habitats resulting in death of plant and animal life. Winni hypothesized that with increased nutrients in a seagrass habitat, the microbiome of the seagrass would change in a way that would have an effect on the overall plant. In order to test this hypothesis, Winni had to carry out controlled lab experiments but not without collecting her test species first. She collected over 200 seagrass individuals as well as buckets of mud from Yaquina Bay, which she took back to Hatfield Marine Science Center where she set up tanks for her experiment. The tanks housed seagrasses and the collected mud. Half of the tanks included added fertilizer to test the effects of nutrient addition, and the other half were left as controls. Over the course of the experiment, Winni tracked plant growth metrics and nitrogen concentrations of the tanks, as well as collecting root and leaf samples to look at the microbiomes on both of those parts of the seagrass.

Winni found that the fertilizer affected the roots in such a way that it changed the microbiome community found there. This change resulted in enrichment for microbes that could cycle sulfur, which could potentially have quite detrimental effects on seagrasses. This is because seagrasses grow in anoxic, or oxygen-low, environments where sulfur is found in its reduced form, hydrogen sulfide. Usually, in environments without excessive nutrient input, seagrasses are able to deal with sulfide, which is typically toxic to plants and animals. However, with increased nutrients, the seagrasses may become overwhelmed by the amount of sulfur in the water as it gets converted into hydrogen sulfide. At certain thresholds, the sulfide ends up becoming toxic to seagrasses. Thus, Winni’s research shows that excessive fertilization to seagrass environments, potentially from land run-off, could have detrimental impacts on seagrasses.

Another chapter of her PhD takes Winni half way across the world to the Mediterranean. Well, it is not so much that it takes Winni to the Mediterranean, it is more that the Mediterranean comes to her! Through her advisor, Winni was able to obtain seagrass samples from the Mediterranean. What makes these samples unique is that they were taken from a site near a naturally occurring underwater volcano. You may be wondering how this is relevant to Winni’s research since she is trying to figure out how human-induced stressors impact seagrasses. Well, the underwater volcano spews carbon dioxide into the water, which makes the water more acidic. This phenomenon is essentially a natural experiment because it mimics the effects of human-induced ocean acidification, which is becoming a problem around the world’s oceans. The results are still underway but they will help fill some of the knowledge gaps concerning the effects of ocean acidification on organisms.

This blog started by emphasizing how important seagrasses are in sequestering carbon, however it is not the only thing that makes these small, unassuming plants so vital to our lives and the lives of many other organisms. Coastal waters with seagrass beds have been found to contain relatively less human pathogens than areas without seagrasses. This is because seagrasses filter the water and are able to remove a lot of pathogens. Furthermore, they are important in preventing coastal erosion and often make coastlines more resilient to storms. Not only are they also important habitats to some beloved marine megafauna (manatees, sharks, turtles) but they are also important for many smaller, but equally ecologically and economically important, species. For example, in Oregon, seagrass beds may actually be helping mitigate ocean acidification which is having a negative impact on oysters as it affects the strength of their shells.

Winni’s life, both at Oregon State and before her arrival here, has not been all about seagrass science though. To hear more about her background and some of the struggles and lessons that she has had during her tenure here, tune in on Sunday, March 8 at 7 PM on KBVR Corvallis 88.7 FM or stream live. To follow Winni and her research, be sure to follow her on Twitter @ramenmicrobiome. Something that we weren’t able to cover on the blog but covered on the show, is that Winni is one of the founders of the Women of Color Caucus (WoCC) at OSU. Read about the origin story of WoCC here, follow their Instagram and Twitter pages and join their listserv here.