Microbiology

UT Faculty Join New $6.5 Million Grant to Study Climate Links Between Algal Blooms and Human Health

by

no photo placeholder image

UT Faculty Join New $6.5 Million Grant to Study Climate Links Between Algal Blooms and Human Health

Profile

Faculty in the University of Tennessee Department of Microbiology are part of a new $6.5 million, five-year federal grant to establish a virtual center for the study of links between climate change, harmful algal blooms, and human health.

Increased precipitation, more powerful storms, and warming Great Lakes waters all encourage the proliferation of harmful algal blooms composed of cyanobacteria, also known as blue-green algae. These microorganisms can produce toxins harmful to humans, pets, and wildlife.

Though the pea-green summer blooms in western Lake Erie are the best-known in the region, cyanobacterial harmful algal blooms, or cHABs, now occur in all five Great Lakes and in fresh waters around the US. These blooms can increase water-treatment costs for local governments and harm vital summer economies in communities that enjoying fishing, swimming, and boating. In the Knoxville area earlier this year, a cHAB of Planktothrix rubescens (“pink algae”) in Meads Quarry at Ijams Nature Center closed swimming and other activity for a month.

Student researchers collect water samples from a cyanobacterial harmful algal bloom in western Lake Erie as part of a project to study the effect of environmental conditions on toxin production by cyanobacteria. Photo by McKenzie Powers

“The University of Tennessee has a 25-plus year history of contributing to research on the security of our water supplies with respect to harmful algal blooms, with the Great Lakes being a major focus,” noted Steven Wilhelm, the Kenneth and Blaire Mossman Professor of Microbiology and one of the project’s leaders.

The UT team, including Wilhelm and David Talmy, assistant professor in the Department of Microbiology, will focus on the effects of a changing climate and identify new players in the biological problems the lake is having. To understand the drivers of toxic algal bloom events, they previously collaborated with researchers in Michigan and Berlin, Germany, on the development of mathematical models that predict toxin production by cells, and how some of the proposed abatement methods may have unintended consequences.

Understanding best abatement practices and projecting the long-term effects of a changing climate—as well as the disruptive storms that go with it—are a major goal of this research. Participants will work across four collective projects to enable an assessment of the human health risks of cHAB toxins. These complementary projects seek to determine how climate change affects cHABs and how cHABs impact human health.

This virtual center was founded at Bowling Green State University in 2018 with funding from the National Institutes of Health and the National Science Foundation. Following the retirement of founding director Professor George Bullerjahn at BGSU, the center’s administrative home moved to Ann Arbor with renewed funding from the two federal agencies under the directorship of University of Michigan (UM) Professor Gregory Dick.

The center maintains core projects as it evolves to pursue new directions informed by more than 70 research papers published in peer-reviewed scientific journals by center-funded scientists since 2018. In addition, center-funded researchers will develop new technologies for advanced monitoring and forecasting of cyanobacterial harmful algal blooms in collaboration with colleagues at NOAA’s Great Lakes Environmental Research laboratory and the U-M-based Cooperative Institute for Great Lakes Research.

“The threat to water resources in the Great Lakes—which hold about 95% of the surface fresh water in the US and support a multibillion-dollar blue economy—is real,” said Dick. “But despite these serious threats, key scientific questions surrounding the climate drivers and health impacts of cHABs remain unresolved. Our knowledge is not yet sufficient to predict how a changing climate will impact cHAB distributions, community composition, or toxicity.” 

Studies will combine observation, experiment, and modeling in areas of lake science, climatology, microbiology, and biomedical science. A community engagement core led by The Ohio State University (OSU) will communicate findings to relevant communities and stakeholders.

In addition to UT, UM and OSU, partners include more than 28 faculty researchers and dozens of students at Bowling Green State University, the University of Toledo, Wayne State University, Michigan State University, University of North Carolina, James Madison University, the State University of New York, and the University of Windsor in Canada.

By Randall Brown

Zepernick Investigates How Freshwater Diatoms Stay in the Light

by

no photo placeholder image

Zepernick Investigates How Freshwater Diatoms Stay in the Light

Profile

Spring weather brings welcome conditions for flowers and plant life to bloom across the land. The right mixture of temperature, moisture, and light helps keep the green world vibrant.

Underwater plant life generally responds to similar environmental encouragements, but a curious discovery in Lake Erie circa 2012 led microbiologists to study an unseasonal display of winter abundance. Blooms of diatoms—microscopic, photosynthetic algae—were alive and well beneath (and within) the lake’s ice cover.

“Some of the main winter-spring diatom bloom formers, like Aulacoseira islandica, have a symbiotic relationship with heterotrophic bacteria capable of forming tiny ice crystals, which over time causes the diatom filaments to become buoyant—just as ice cubes float in your favorite beverage,” said Brittany Zepernick, a post-doctoral researcher and SEC Emerging Scholar in UT’s Department of Microbiology.

These ‘diatom ice cubes’ float to the Lake Erie ice cover and embed within it, putting them in position to absorb the light needed to perform photosynthesis throughout the winter months. It was good news for diatoms, which are a vital component of the cumulative ecosystem in lakes and oceans across the globe

This curious adaptation is threatened, though, as warming global temperatures have led to widespread ice decline across the Great Lakes, leaving Lake Erie in a nearly ice-free state in several recent winters and leaving diatoms stuck in murky, light-deprived waters. In these new “climatically uncharted waters,” the adaptations that benefitted these winter diatoms for so long suddenly ceased to serve them.

So, what’s a diatom to do? Zepernick and colleagues turned to the shores of Lake Erie to investigate the evolving situation. With the help of the US and Canadian Coast Guard, they sampled the ice-covered (in 2019) and ice-free (in 2020) winter waters of Lake Erie to learn how diatoms were responding to changing environmental conditions. They recently published their work in the ISME Journal—Multidisciplinary Journal of Microbial Ecology.

Two main diatom genera dominate the winter blooms: Aulacoseira islandica and Stephanodiscus spp.

“The abundance of Stephanodiscus spp. was approximately 70 percent lower in the ice-free water column of 2020 compared to the ice-covered water column of 2019,” said Zepernick. “Likewise, the abundance of Aulacoseira islandica was around 50 percent lower in the ice-free water column compared to the ice-covered water column.”

Ice floating on the surface of Lake Erie
Diatoms adapted to embed in Lake Erie’s ice cover—can they adapt to stay afloat without ice?

With ice cover across the Great Lakes at record lows—from around 80 percent covered in ice in 2018 and 2019 to just 8 percent covered in 2023—researchers expect this trend will continue in future winters. 

The next step is studying how this impacts Lake Erie, which joins the other Laurentian Great Lakes of the US and Canada to cumulatively contain approximately 20 percent of the globe’s fresh water.

“Despite the critical importance of this system, we didn’t know diatom blooms even formed in the winter-spring months until around 2012,” said Zepernick. “Many researchers have referred to the winter water column as a ‘New Frontier’ or a ‘black box.’ What we do know is that diatoms are critically important to regional lake ecosystems and global climate.”

Diatoms make up an estimated 20 percent of global carbon sequestration and oxygen production, play an enhanced role in global biogeochemical cycles, and represent a critical component of the aquatic ecosystem in freshwater systems.

“Hence, the large-scale changes already underway to the winter-spring diatom communities in Lake Erie and other lakes across the globe will result in large-scale biological and biogeochemical change,” said Zepernick.

The light at the end of the icy tunnel could rely on the diatoms’ potential to adapt. Zepernick’s recent work indicates they could possibly form clusters with adhesive proteins called fasciclins to “raft” to the surface of the muddy waters via “underwater waves” produced by wind, convection, and underwater currents.

Another adaptation Zepernick hinted at was that diatoms could increase their use of proton-pumping rhodopins (PPRs)—light harvesting, retinal-containing proteins that could serve as an alternative to classical photosynthesis. She is currently attempting to isolate freshwater diatoms from Lake Erie samples that possess PPRs to create a model freshwater diatom-PPR system for further study. Her findings could offer clues to the diatoms’ next move in a rapidly changing climate.

“PPRs are a hot topic within marine literature, yet we know very little about how these mechanisms apply to freshwater systems and taxa,” she said. “I am interested in elucidating the benefits PPRs may confer to both freshwater and marine diatoms across a variety of emerging—and future—climatic stressors.”

Fall 2023: We are Hiring!

by

no photo placeholder image

Fall 2023: We are Hiring!

Profile

Multiple Track and Rank Faculty Positions in Microbiology, Immunology, Plant-Microbe Interactions and Microbial Physiology!!

The Department of Microbiology at the University of Tennessee at Knoxville is seeking candidates for three tenure-track and one lecturer/lab coordinator faculty appointments.  Successful candidates are anticipated to start these positions August 1, 2024. UTK is a land-grant university and values engaged forms of research/scholarship/creative activity, teaching and service and considers evidence of these commitments in the records of applicants.

Position 1. We seek candidates at the rank of Associate or Full Professor (9-month, tenure-track) researching plant-associated microbes using molecular, genetic, biochemical, mathematical modeling and/or cell biology approaches. Specific areas of interest include, but are not limited to:

  • Plant-microbe interactions in the context of resilience in agricultural ecosystems and maintaining plant-growth promoting microbes
  • Plant-microbe-mediated resistance and mitigation of pathogens
  • Mechanistic linkage of plant-microbiome composition, function and crop growth from microscopic to regional scales
  • Tritrophic interactions among plants, microorganisms, pollinators, and/or herbivores

Full details available here: http://apply.interfolio.com/131119

Position 2. We seek candidates at the rank of Assistant Professor (9-month, tenure-track) that study host immune responses to microbes using molecular, genetic, biochemical, and/or cell biological approaches. Specific areas of interest include, but are not limited to:

  • Host responses to bacteria, fungi, protozoa (parasites), viruses, and/or helminths
  • Innate or adaptive immune responses to microbes
  • Innovative model systems for host-microbe immune focused interactions, including primary, zoonotic, and opportunistic pathogens or commensal species
  • Immune interactions at mucosal surfaces, including lungs, is of particular interest, but any niche will be considered

Full details available here: http://apply.interfolio.com/130937

Position 3. We seek candidates at the rank of Assistant Professor (9-month, tenure-track) in the area of microbial physiology. Specific areas of interest include, but are not limited to:

  • Experimental models that answer the “how” and “why” of microbial systems
  • The physiology of microorganisms including bacteria, eukaryotes, and archaea
  • The physiological effects of viral infection on microorganisms
  • Interactions of microbes with their microbiomes and environments
  • Lab model systems that resolve mechanistic links between microbes or microbiomes and their environment

Full details available here: http://apply.interfolio.com/130406

Position 4. We seek candidates for a Lecturer and Instructional Laboratory Coordinator (12-month, non-tenure track). The position is renewable yearly, contingent upon evidence of excellence in teaching and performance of programmatic duties. Principal duties involve (i) teaching an introductory microbiology course and (ii) coordinating the administration of multiple microbiology lab courses (from introductory, non-majors to upper-level majors) each semester. Responsibilities include curricular development as well as mentoring and supervision of laboratory graduate student teaching assistants (GTAs). 

Full details available here: http://apply.interfolio.com/131123

The Department of Microbiology values the quality of life of all its members and is committed to supporting the intercultural goals of the University.  Located in the foothills of the Smoky Mountains, The University of Tennessee Knoxville was founded in 1794 and is one of the oldest public universities in the nation. There are over 30,000 students enrolled at the Knoxville campus, who train and study in a city where excellence in academia meets the natural beauty of the southern Appalachian region and in the company of the artists, makers, and entrepreneurs that call Knoxville their home.

Wilhelm Receives John H. Martin Award for Research

by

no photo placeholder image

Wilhelm Receives John H. Martin Award for Research

Profile

The Association for the Sciences of Limnology and Oceanography (ASLO) presents the John H. Martin Award to one paper each year that has led to fundamental shifts in research focus and interpretation of a large body of previous observations.

The 2021 John H. Martin Award is for “Viruses and nutrient cycles in the sea,” by Steven Wilhelm (University of Tennessee) and Curtis Suttle (University of British Columbia). The award will be presented at the 2021 ASLO Aquatic Sciences Virtual Meeting in June.

Wilhelm and Suttle’s foundational 1999 paper originated the concept of the ‘viral shunt,’ the phenomenon in which viral infection of marine microbes redirects flow of organic matter away from higher trophic levels and through the microbial loop. Drawing on early estimates of viral production in the water column, Wilhelm and Suttle shined a light on the considerable role viruses play in ocean biogeochemical cycles at a time when much of the research was focused on describing viral diversity and distribution. Their calculations showed that a staggering 25% of all photosynthetically fixed carbon, and associated nutrients, in the ocean may be recycled through the viral shunt.

Additionally, Wilhelm and Suttle made some of the first estimates of the total carbon stored in the viral pool and made eye-opening comparisons to the carbon stored in other types of marine organisms (including whales). Today, the concept of the viral shunt continues to influence our understanding of ocean ecosystem functioning and nutrient cycles. With >1000 citations, and more than 300 in the last five years, the legacy of “Viruses and nutrient cycles in the sea” and the viral shunt concept is still strongly felt in the field today.

“Every so often a novel concept is described which truly transforms a scientific field for decades,” says ASLO President Roxane Maranger. “Wilhelm and Suttle’s conception of the ‘viral shunt’ as a major pathway of oceanic carbon and nutrient flow in their 1999 paper is a stunning example of such a transformation.”

Full Citation: Wilhelm, S.W. and C.A. Suttle. 1999. Viruses and nutrient cycles in the sea, BioScience 49(10): 781-788. doi.org/10.2307/1313569.

ASLO is an international aquatic science society that was founded in 1948. For more than 60 years, it has been the leading professional organization for researchers and educators in the field of aquatic science. The purpose of ASLO is to foster a diverse, international scientific community that creates, integrates and communicates knowledge across the full spectrum of aquatic sciences, advances public awareness and education about aquatic resources and research, and promotes scientific stewardship of aquatic resources for the public interest. Its products and activities are directed toward these ends. With more than 3,800 members worldwide, the society has earned an outstanding reputation and is best known for its journals, interdisciplinary meetings, and special symposia. For more information about ASLO, please visit our website at www.ASLO.org.