Marine Biological Laboratory — Biological Discovery in Woods Hole

Caught on Camera: The Bacterial Communities 'Hitchhiking' on Marine Plastic Trash

Contact: dkenney@mbl.edu; 508-685-3525

The structure of microbial communities colonizing microplastics collected from the North Atlantic Ocean (Vineyard Sound, Woods Hole, Mass.) This image reveals the phylogenetic affiliations of different bacterial groups. Large ellipsoid and pennate yellow cells= diatoms; long filamentous cell across center = cyanobacteria; blue= general bacteria; yellow rods = Bacteroidetes; red = Alphaproteobacteria; cyan= Rhodobacteraceae. Scale bar is 2 micrometers. Imaging technology is confocal laser-scanning and CLASI-FISH. Credit: Cathleen Schlundt

WOODS HOLE, Mass. – Millions of tons of plastic trash are fouling the world’s ocean, most of it tiny pieces of microplastic less than a quarter-inch in size. Even the smallest marine animals can ingest these microplastics, potentially threatening their survival.

MBL Fellow Linda Amaral Zettler of the NIOZ Royal Netherlands Institute for Sea Research and the University of Amsterdam.

Marine microplastics aren’t floating solo, either – they quickly pick up a thin coating of bacteria and other microbes, a biofilm known as “The Plastisphere." These biofilms can influence the microplastics’ fate – causing them to sink or float, or breaking them down into even tinier bits, for example. They can even make the plastic smell or taste like food to some marine organisms. But very little is known about what kinds of microbes are in the Plastisphere, and how they interact with one another and the plastic.

Now, using an innovative microscopy method developed at the Marine Biological Laboratory (MBL), Woods Hole, scientists have revealed the structure of the microbial communities coating microplastic trash collected from a variety of ocean sites. The team, led by Linda Amaral-Zettler (who coined the term “Plastisphere”), Jessica Mark Welch, and Cathleen Schlundt, reports its results this week in Molecular Ecology Resources.

The MBL team built upon an fluorescence imaging technique developed by Mark Welch and colleagues to literally see the spatial organization of microbes on the plastic samples. They did so by designing probes that fluorescently lit up and targeted major, known bacterial groups in the Plastisphere.

“We now have a toolkit that enables us to understand the spatial structure of the Plastisphere and, combined with other methods, a better future way to understand the Plastisphere’s major microbial players, what they are doing, and their impact on the fate of plastic litter in the ocean,” said Amaral-Zettler, a MBL Fellow from the NIOZ Royal Netherlands Institute for Sea Research and the University of Amsterdam.

From left, co-authors Cathleen Schlundt, now at Helmholtz Centre for Ocean Research Kiel, and MBL Associate Scientist Jessica Mark Welch at the MBL.

The scientists saw diatoms and bacteria colonizing the microplastics, dominated in all cases by three phyla: Proteobacteria, Cyanobacteria, and Bacteriodetes. Spatially, the Plastisphere microbial communities were heterogeneously mixed, providing the first glimpse of bacterial interactions on marine microplastics.

Mark Welch and colleagues have previously applied their imaging technology to study microbial communities in the human mouth and in the digestive tract of cuttlefish and vertebrates.

This study customized and extended the technology, called CLASI-FISH (Combinatorial Labeling And Spectral Imaging Fluorescence In Situ Hybridization). Amaral Zettler finds the technology so powerful, she plans to establish a CLASI-FISH microscopy platform in the Netherlands.

Citation:

Cathleen Schlundt, Jessica L. Mark Welch, Anna M. Knochel, Erik R. Zettler, and Linda A. Amaral-Zettler (2019). Spatial Structure in the “Plastisphere”: Molecular Resources for Imaging Microbial Communities on Marine Plastic Debris. Mol. Ecol. Resources, DOI 10.1111/1755-0998.13119.

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

Deepening Diversity: First In-Depth Study of Marine Fungi and Their Reproduction Emerges from MBL

Contact: Diana Kenney
dkenney@mbl.edu; 508-289-7139

By Stephanie McPherson

Fungal colonies cultured from samples collected in various Woods Hole marine environments. Credit: Lorna Mitchison-Field

WOODS HOLE, Mass. -- Marine fungi have long been overlooked in the research community, despite their likely contributions to the health of ocean ecosystems. Now, a first deep dive into the diversity of marine fungi and their cell division cycles has been published by a collaborative team at the Marine Biological Laboratory (MBL), opening the door on this oft-neglected branch of the Kingdom Fungi.

“There's hardly anything known about fungi in the marine environment,” says Amy Gladfelter, MBL Fellow from the University of North Carolina at Chapel Hill and senior author on the new study, published in Current Biology. “This was an opportunity to understand who might be there and what they're doing, and also discover some new fungal systems that might display interesting biology.”

The paper describes 35 species of marine fungi collected from various sites around Woods Hole, many of which have never been studied before. The team found plenty of surprises, including unconventional cell division cycles in certain black fungi often found in extreme ocean environments.

“There's a lot of diversity in marine fungi—morphological and species diversity, possibly ecological functional diversity—that we don't know a lot about yet. And it's really worth digging into,” says Lorna Mitchison-Field, first author on the paper.

The research project was borne from Gladfelter’s long-time interest in fungi and their cell biological processes, such as polarity and cell division. She partnered with Christine Field, Lecturer at Harvard University and MBL Whitman Center scientist, and Mitchison-Field, who was an undergraduate at Mount Holyoke College during the bulk of the project and spent their summers at MBL.

Mitchison-Field took advantage of the MBL’s Marine Resources Center to gather samples from local sites.

“We brought back samples from coastal water, marshes, beaches, and other environments and plated them out on different kinds of media with nutrients, hoping to culture fungi,” says Mitchison-Field. “Then I observed the colony growth through a period of usually one to two-and-a-half weeks. As they grew, I would pick specific colonies to isolate and we'd look at those using [time-lapse] differential interference contrast (DIC) microscopy.”

Lorna Mitchison-Field collecting water samples from Buzzards Bay with Scott Bennett of the MBL Marine Resources Center. Credit: Amy S. Gladfelter

A group of black yeast species proved particularly interesting. One species produced multiple buds per cell cycle, rather than the single bud seen in the classical model of fungal reproduction. Another species alternated its methods of reproduction, switching between fission and budding each cell-division cycle.

Being the first study of its kind, their paper is already making waves in cell biology. (See Commentary, here.)

“The reaction that we've gotten from cell biologists…is a sense of wonder,” says Gladfelter. “Like, ‘Wow, there's so much out there still that we don't know.’ We hope this inspires people to keep looking for new biology in this incredibly diverse biosphere that has only barely been studied.”

Because they found so many different types of fungi in such varied locations, the team hopes to study how fungi interact with their environments.

“One future hope is that we can start looking at fungi in the context of different hosts,” says Gladfelter, “taking not just a culture-based approach, but a metagenomics identification of everybody who's there and what sort of genes they're expressing.”

Mitchison-Field has spent many summers in Woods Hole with their parents, Christine Field and Tim Mitchison, longtime MBL Whitman Center scientists from Harvard University. This MBL collaboration with Gladfelter and several other visiting scientists allowed Mitchison-Field, while still an undergraduate, to strengthen field and lab work skills in a real-world setting, resulting in their first paper as a first author.

The black yeast Hortaea werneckii dividing by fission and budding (DIC microscopy).
Credit: Lorna M.Y. Mitchison-Field et al (2019) Current Biology, doi: 10.1016/j.cub.2019.08.050

Citation:

Lorna M.Y. Mitchison-Field et al (2019) Unconventional Cell Division Cycles from Marine-Derived Yeasts. Current Biology, doi: 10.1016/j.cub.2019.08.050

Commentary:

Corey A.H. Allard and James B. Moseley (2019) Cell Biology: Marine Yeasts Deepen the Sea of Diversity. Current Biology, doi: 10.1016/j.cub.2019.09.22

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Embryology Course Image Wins Top Prize in Nikon Small World Contest

Contact: dkenney@mbl.edu; 508-289-7139

By Stephanie McPherson

WOODS HOLE, Mass.—A vibrantly colored image of a turtle embryo taken by two members of the Marine Biological Laboratory (MBL) community has won first place in the 45^th Nikon Small World International Photomicrography Competition. Teresa Zgoda and Teresa Kugler used fluorescence and stereo microscopy during the 2017 MBL Embryology course to capture the winning image in a masterful example of image-stitching. The competition is regarded as the leading forum for showcasing the beauty and complexity of life as seen through the light microscope.

This fluorescent turtle embryo image, captured in the 2017 MBL Embryology course by Teresa Zgoda and Teresa Kugler, has taken the top prize in the 2019 Nikon Small World Photomicrography Competition.

“[The Small World Competition] is a fantastic contest to share beautiful scientific imagery,” says Zgoda. Their turtle image competed against more than 2,000 other submissions to win the top prize.

“We placed the turtle embryo in a petri dish and autofluorescence was photographed using three wavelengths of light. The final image is a composite of hundreds of images, since the embryo was so large,” says Zgoda. They captured the images with a Zeiss Discovery v20 stereo microscope and used a technique called image-stitching to produce the final image.

Another Embryology course image drew the judges' attention: an octopus embryo taken by 2018 course student Martyna Lukoseviciute and MBL's Carrie Albertin landed in 19th place.

Both Zgoda and Kugler are passionate micro-photographers, saying it's a hobby that allows them to explore their dual passions of science and artistic pursuits. Their winning image exemplifies the blend of science and art Nikon Small World aims to bring to the public each year.

When they captured the winning image, Zgoda and Kugler were interns with the imaging company Zeiss, which is stationed at MBL to assist students enrolled in the MBL's Advanced Research Training courses in using Zeiss microscopes.

The partnership between MBL and commercial vendors of laboratory equipment, including powerful microscopes from Nikon, Zeiss and other companies, is critical to the success of these world-renown courses.

“We are honored to have MBL community members recognized by the Nikon International Small World Competition,” says MBL Director Nipam Patel. “MBL has a long history of being at the forefront of developing new approaches in imaging and applying those methods to biological problems and questions. We are grateful to the commercial vendors who help make that possible.”

The MBL’s inherently collaborative nature has long been fertile ground for scientific progress, and the development and use of cutting-edge scientific technology.

“You are exposed to so much wonderful science at the MBL,” says Zgoda. “The courses they run are so in depth and offer a plethora of different subjects to image.”

“Nikon is a leading brand in photography, and it means so much to me that they chose this image for first place," she says.

Zgoda and Kugler’s image will be on display at the MBL next summer as part of the Nikon Small World Exhibit, which is shown throughout North America at selected museums and centers for science. The MBL is the only Massachusetts stop on the exhibit tour.

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