Ishaq Lab presentations and live discussions at Ecological Society of America virtual meeting

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Next week kicks off the live events, including with question + answer, discussions, and special sessions being held in real time, for the Ecological Society of America’s annual conference, which is being held virtually this year. Prerecorded presentations are already available on demand.

Can a necromenic nematode serve as a biological Trojan horse for an invasive ant?

Session 1-PS7: Vital Connections in Ecology: Breakthroughs in Understanding Species Interactions

Poster and narration available on demand.

Live discussion: Monday, August 2, 2021, 9:30 AM – 10:30 AM Pacific Time

Abstract:

Background/Question/Methods
The invasive European fire ant (Myrmica rubra) threatens native ant species and human health along the coast of Maine, United States. M. rubra mortality has been associated with infection by Pristionchus entomophagus, a necromenic nematode that is hypothesized to transfer pathogenic bacteria acquired from the environment to ant colonies. To investigate this hypothesis, we conducted a series of experiments on nematode-infected ants collected from Mount Desert Island. First, we isolated bacteria cultured from nematodes emerging from M. rubra cadavers and assessed the ability of the nematodes to acquire and transfer environmental bacteria to Galleria mellonella waxworm larvae. Second, we identified bacteria which were potentially transferred from nematodes to infected ant nests on MDI using bacterial community similarity and sequence tracking methods.

Results/Conclusions
Multiple bacterial species, including Paenibacillus spp., were found in the nematodes’ digestive tract. Serratia marcescens, Serratia nematodiphila, and Pseudomonas fluorescens were collected from the hemolymph of nematode-infected G. mellonella larvae. Variability was observed in insect virulence in relation to the site origin of the nematodes. In vitro assays confirmed uptake of red fluorescence protein (RFP)-labeled Pseudomonas aeruginosa strain PA14 by nematodes. Bacteria were highly concentrated in the digestive tract of adult nematodes, some bacteria were observed in the digestive tract of juveniles with a more significant amount on their cuticle, and none on the cuticle of adults. RFP-labeled P. aeruginosa were not observed in hemolymph of G. mellonella larvae, indicating an apparent lack of bacterial transfer from juvenile nematodes to the insects despite larval mortality.

Host species was the primary factor affecting bacterial community profiles. Spiroplasma sp. and Serratia marcescens sequences were shared across ants, nematodes, and nematode-exposed G. mellonella larvae. Alternative to the idea of transferring bacteria from environment to host, we considered whether nematode-exposure might disorder or depauperate the endobiotic community of an insect host. While total bacterial diversity was not statistically lower in nematode-exposed G. mellonella larvae when compared to controls, 16 bacterial sequence variants were less abundant in nematode-exposed larvae, while three were increased, including Serratia, Pseudomonas, and Proteus.
This study suggests that transfer of bacteria from nematodes to ants is feasible, although largely serendipitous, and may contribute to ant mortality in Maine. Hypothetically, the use of an engineered biological control, such as nematodes carrying specifically-seeded bacterial species, may be effective, especially if the pathogenic bacteria are naturally found in soil ecosystems and represent a low risk for biosafety control.

Poster Citation: Hotopp*, A., Silverbrand, S., Ishaq, S.L., Dumont, J., Michaud, A.,  MacRae, J.,  Stock, S.P.,  Groden, E. “Can a necromenic nematode serve as a biological Trojan horse for an invasive ant?” Ecological Society of America 2021. (virtual). Aug 2-6, 2021. (poster)

Recent Press and Publications:

“Bacteria from nematodes could be used to kill fire ants, UMaine research reveals”, Marcus Wolf, University of Maine news, July 27, 2021.

Ishaq, S.L., A. Hotopp2, S. Silverbrand2, J.E. Dumont, A. Michaud, J. MacRae, S. P. Stock, E. Groden. 2021. Assessment of pathogenic bacteria transfer from Pristionchus entomophagus (Nematoda: Diplogasteridae) to the invasive fire ant (Myrmica rubra) and its potential role in  colony mortality in coastal Maine. iScience 24(6):102663. Article.

Talk #93066, “The effect of simulated warming ocean temperatures on the bacterial communities on the shells of healthy and epizootic shell diseased American Lobster (Homarus americanus)”

COS 87: Climate Change: Communities 1
Recorded talk available on demand.

Live discussion: Wednesday, August 4, 2021, 12:00 PM – 1:00 PM Pacific Time
The presentation will be available on demand starting on July 26th, and requires registration to the ESA conference.

Abstract

Background, question, and methods

The American lobster, Homarus americanus, is a vital species for the fishing industry along the North Atlantic coast of North America. However, populations in Southern New England have declined, most likely due to increasing ocean temperatures and prevalence of emerging disease. Our previous work suggested that temperature may not be the sole cause for epizootic shell disease (ESD). Here, we examined the shell bacterial communities and progression of ESD in non-shell diseased and diseased adult female lobsters under three simulated seasonal temperature cycles for a year.

Fifty-seven female lobsters were wild-caught from Maine’s management zones F and G, and were assessed for shell disease progression on a scale of 0 (no observable signs) to 3 (visible disease on >50% of the shell surface). ESD-negative lobsters (apparently healthy) and ESD-positive (diseased) lobsters were randomly dispersed into 3 systems, and within each system, healthy and diseased lobsters were placed into separate tanks. These systems were maintained at three temperature ranges comparable to the average seasonal ocean temperatures for Southern New England (SNE), Southern Maine (SME), and Northern Maine (NME) regions. Samples were collected at three timepoints, a baseline “summer” temperature where all tanks were the same temperature, a winter temperature four months later, and a summer temperature 10 months after that.

A total of 131 experimental samples, plus 10 controls, passed PCR amplification, amplicon quantification and purification, Illumina MiSeq ver. 4 sequencing, and quality-control filtering.  Sequences were processed using the R software platform, using DADA2, phyloseq, vegan, and assorted other packages.

Results and conclusions

The bacterial richness on lobster shells at the baseline timepoint, when lobsters were wild-caught, was higher than the winter time point, 4 months later, or the summer time point, 10 months later, for the same lobsters after having been kept in tanks, regardless of their temperature or shell disease status.  Similarly, the bacterial community membership (unweighted Jaccard similarity) was similar for all samples at baseline, but diverged for later time points.

Tank temperature significantly affected microbial community membership (unweighted Jaccard similarity), as well as the abundance of those community members (weighted Bray-Curtis dissimilarity).

Contrary to our expectations, ESD shell disease index did not progress over time or in warmer conditions, and we hypothesized that frequent tank water changes and shell moltings may have reduced the microbial load. Preliminary results indicate that shell stage and shell disease index were positively associated with increased bacterial richness on lobster shells.

Citation: Ishaq*, S.L., Lee, G., MacRae, J., Hamlin, H., Bouchard, D. “The effect of simulated warming ocean temperatures on the bacterial communities on the shells of healthy and epizootic shell diseased American Lobster (Homarus americanus).” Ecological Society of America 2021. (virtual). Aug 2-6, 2021. (accepted talk)

For some reason the ESA meeting site kept my Montana affiliation from 2017 for all 3 of my submissions.

SS 17: “Microbiomes and Social Equity” (19205)

Prerecorded content available on demand.

Live discussion: Thursday, August 5th, 2021, 9:30 AM – 10:30 AM Pacific Time

Microbiomes — environmental, human and other organismal symbionts — are increasingly seen as critical physiological, developmental and ecological mediators within and among living things, and between the latter and our abiotic environments. Therefore, it is no surprise that microbial communities may be altered, depleted or disrupted by social and economic determinants. Social inequality entails concrete alterations and differentiation of microbial communities among social groups, by way of such factors as nutritional access, environmental pollutants or green space availability, often to the detriment of human and ecosystem health. This special session will be organized as a panel discussion with break-out groups in order to provide participants the opportunity to discuss the ways in which social inequity interacts with microbiomes, and how we might intervene as scientists and communities to promote favorable microbiomes while advancing social equality. We hope to generate research questions and actionable items.

Panel speakers: Michael Friedman, Naupaka Zimmerman, Justin Stewart, Monica Trujillo, Sue Ishaq, Sierra Jech, Jennifer Bhatnagar, and Ariangela Kozik

ESA meeting program: https://www.esa.org/longbeach/

Citation: The Microbes and Social Equity Working group, “Special Session 17: “Microbiomes and Social Equity” (19205).”, Ecological Society of America 2021. (virtual). Aug 5, 2021.

Recent Publication:

Ishaq, S.L., Parada Flores, F.J., Wolf, P.G., Bonilla, C.Y., Carney, M.A., Benezra, A., Wissel, E., Friedman, M., DeAngelis, K.M., Robinson, J.M., Fahimipour, A.K., Manus, M.B., Grieneisen, L., Dietz, L.G., Chauhan, A., Pathak, A., Kuthyar, S., Stewart, J.D., Dasari, M.R., Nonnamaker, E., Choudoir, M., Horve, P.F., Zimmerman, N.B., Kozik, A.J., Darling, K.W., Romero-Olivares, A.L., Hariharan, J., Farmer, N., Maki, K., Collier, J.L., O’Doherty, K., Letourneau, J., Kline, J., Moses, P.L., Morar, N. 2021. Introducing the Microbes and Social Equity Working Group: Considering the Microbial Components of Social, Environmental, and Health Justice. mSystems 6:4.

Introducing the Microbes and Social Equity Working Group: Considering the Microbial Components of Social, Environmental, and Health Justice

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The Microbes and Social Equity Working Group is delighted to make its published debut, with this collaboratively-written perspective piece introducing ourselves and our goals. You can read about us here.

This piece also debuts the special series we are curating in partnership with the scientific journal mSystems; “Special Series: Social Equity as a Means of Resolving Disparities in Microbial Exposure“. Over the next few months to a year, we will be adding additional peer-reviewed, cutting edge research, review, concept, and perspective pieces from researchers around the globe on a myriad of topics which center around social inequity and microbial exposures.

Ishaq, S.L., Parada, F.J., Wolf, P.G., Bonilla, C.Y., Carney, M.A., Benezra, A., Wissel, E., Friedman, M., DeAngelis, K.M., Robinson, J.M., Fahimipour, A.K., Manus, M.B., Grieneisen, L., Dietz, L.G., Pathak, A., Chauhan, A., Kuthyar, S., Stewart, J.D., Dasari, M.R., Nonnamaker, E., Choudoir, M., Horve, P.F., Zimmerman, N.B., Kozik, A.J., Darling, K.W., Romero-Olivares, A.L., Hariharan, J., Farmer, N., Maki, K.A., Collier, J.L., O’Doherty, K., Letourneau, J., Kline, J., Moses, P.L., Morar, N. 2021. Introducing the Microbes and Social Equity Working Group: Considering the Microbial Components of Social, Environmental, and Health Justice. mSystems 6:4.

Interview with WeTalkScience: animal microbiome

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A few weeks ago, I sat down with Sheba A-J, one of the producers of the WeTalkScience podcast, to talk about one of my recent publications in the research journal iScience, at which Sheba is also an editor. Listen to find out how lobsters are like humans, how I got involved on a project working with ants and nematodes, and how you can help make science a more welcoming place.

The Animal Microbiome

The full publication is:

Ishaq, S.L., A. Hotopp, S. Silverbrand, J.E. Dumont, A. Michaud, J. MacRae, S. P. Stock, E. Groden. 2021. Bacterial transfer from Pristionchus entomophagus nematodes to the invasive ant Myrmica rubra and the potential for colony mortality in coastal Maine. iScience 24(6):102663. Article.

Tindall defended her master’s thesis!

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Photo of woman in front of mountains

Excitingly, master’s of science graduate student Tindall Ouverson successfully defended her thesis! Tindall is a student at Montana State University, and took over a collaborative project that stretches back when I left my postdoc position (to head to another job) in the Menalled Lab in 2017. Earlier this year, her first scientific paper was published, Temporal soil bacterial community responses to cropping systems and crop identity in dryland agroecosystems of the Northern Great Plains. More recently, she won first prize in the graduate students poster competition at the 2021 Montana State University LRES research colloquium.

Now that she has defended, Tindall will focus on revising the research thesis chapter which was not already published into a manuscript to submit for review at a scientific journal. After that, she is planning on pursuing her career in agricultural sustainability research and outreach.

RESPONSE OF SOIL BACTERIAL COMMUNITIES TO CROPPING SYSTEMS, TEMPORAL CHANGES, AND ENVIRONMENTAL CONDITIONS IN THE NORTHERN GREAT PLAINS

by

Laura Tindall Ouverson

Master of Science

Land Resources and Environmental Sciences

MONTANA STATE UNIVERSITY

Bozeman, Montana

July 12 2021

ABSTRACT

Soil bacterial communities are essential components of the soil ecosystem that support crop production and indicate a soil’s health. However, agriculture in semiarid drylands and their associated soil bacterial communities face increasingly warmer and drier conditions due to climate change. Two complementary studies were conducted to assess the response of soil bacterial communities to cropping systems, temporal changes, and soil temperature and moisture conditions in semiarid, dryland agricultural systems of the Northern Great Plains. 

The first study focused on soil bacterial community response to crop phase (i.e., crop species) of a rotation in contrasting cropping systems (chemical inputs and no-till, USDA-certified organic tilled, and USDA-certified organic sheep grazed) over a growing season. Organic grazed management supported more diverse bacterial communities than chemical no-till, though diversity in all systems decreased over the growing season. Organic grazed bacterial communities were distinct from those in the organic tilled and chemical no-till systems. An interaction between cropping system and crop phase affected community dissimilarity, indicating that overarching management systems and environmental conditions are influential on soil bacterial communities.

The second study evaluated soil bacterial communities in a winter wheat-cover crop or fallow rotation. Observations were conducted in the summer fallow and two cover crop mixtures differing by species composition and phenologies, terminated by three different methods (chemical, grazing, or haying), and subjected to either induced warmer/drier or ambient soil conditions. Only the presence and composition of cover crops affected bacterial community dissimilarity. Bacterial communities responded to an interaction between the presence and composition of cover crops and environmental conditions, but not termination. Additionally, soil bacterial communities from mid-season cover crops were distinct from early season and fallow. No treatments affected bacterial communities in 2019, which could be attributed to historic rainfall. Cover crop mixtures including species tolerant to warmer and drier conditions can foster diverse soil bacterial communities compared to fallow soils.

Overall, these studies increased our understanding of how soil bacterial communities respond to soil health building practices in the Northern Great Plains. Cropping systems can foster unique soil bacterial communities, but these effects may be moderated by environmental and temporal conditions.

Pilot project funded to study Vibrio bacteria in scallop farming

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A collaborative pilot project was funded by the Maine Food and Agriculture Center (MFAC) to investigate Vibrio bacteria in scallop hatcheries in Maine! This will support some ongoing work by a collaborative research team at UMaine and the Downeast Institute, as we develop a long-term, larger-scale project investigating scallop health and survival in hatcheries, something which will be critical to supporting sustainable and economically viable aquaculture productions.

“Investigating microbial biofilms in Maine hatchery production of sea scallop, Placopecten magellanicus.”

Principal Investigator: Sue Ishaq

Co-Investigators:

  • Dr. Tim Bowden, Associate Professor of Aquaculture, University of Maine
  • Dr. Jennifer Perry, Assistant Professor of Food Microbiology, University of Maine
  • Dr. Brian Beal, Professor of Marine Ecology, University of Maine at Machias; and Research Director/Professor, Downeast Institute
  • Dr. Erin Grey, Assistant Professor of Aquatic Genetics, University of Maine

Project Summary: Atlantic deep-sea scallops, Placopecten magellanicus, are an economically important species, generating up to $9 million in Maine alone. Despite their potential to the aquaculture industry, hatchery-based sea scallop production cannot rely on the generation of larvae to produce animals for harvest. In hatcheries, the last two weeks of the larval maturation phase is plagued by massive animal death, going from 60 million scallop larvae down to a handful of individuals in a span of 48 hours. This forces farmed scallop productions to rely on collection of wild scallop spat (juveniles), but wild population crashes, habitat quality, harvesting intensity, and warmer water temperatures threaten the sustainability and economic viability of this industry. The reasons for sea scallop larvae death remain unknown, but other cultured scallop species are known to suffer animal loss from bacterial infections, including from several bacterial species of  Vibrio and Aeromonas. At the Downeast Institute in Beals, Maine, biofilms appear on tank surfaces within 24 hours. Routine screening for the presence of Vibrio sp. in tanks at DEI reveals no obvious signs of colonies in scallop tanks. Preliminary culturing and genetic identification from these biofilms suggests a species of Pseudoalteromonas, known biofilm formers which outcompete or inhibit other microorganisms. Our goal is to investigate the dynamics of tank surface biofilms in bivalve aquaculture facilities. Our long-term goals are to understand microbial community assembly and animal health during scallop hatchery production, and to standardize management practices to enhance the success of cultured scallop production.  

Experimental design schematic for this project. Our objectives are to 1) Identify the microbial community members involved in tank biofilms, and if it is a repeated or novel community assembly, and 2) Test for biofilm antagonism in vitro, using competing microorganisms, chemical treatments, and environmental conditions. 

Paper published on animal feed and rumen bacteria

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I’m delighted to announce that a paper was published on the effect of a dietary additive on the rumen and fecal bacterial communities in dairy cattle, in the journal Animal: The International Journal of Animal Biosciences!

A lot of factors can be manipulated to help get the most out of one’s diet, including the source and processing method of the ingredients – in most cases in livestock feed: plants. Growing plants for animal feed can be expensive, and often nutrients in plants become more available to the animal after the plant has been processed/broken down in some way. This sometimes allows for food byproducts to be reused for animal feed, and one common example is used brewers’ grains. Once the grains have been fermented to produce alcohol, the simple sugars have been used up but a lot of the complex sugar carbohydrates – in other words: fiber – are left over. Ruminants don’t need simple sugars, but they do need a lot of fiber, and brewers’ grains have been investigated for their usefulness for animal nutrition because they are a cheap, readily-available, and common source of fiber, as well as protein.

The original experiment for this work took place several years ago, and involved an animal feeding trial which added reduced-fat distillers’ grains with solubles into dairy cattle feed. The research team found no negatives effect on milk production or animal health, and that work was previously published. To add to that project, the original research team wanted to know if the diet would drastically change the bacterial community living in the rumen, which would have implications for feed digestion and animal health.

A collaborator of mine donated the cow microbial community DNA data to my AVS 590 special topics in DNA Sequencing Data Analysis course in spring 2020 (now formally registered as AVS 454/554). I worked with UMaine graduate students Adwoa Dankwa and Usha Humagain over the semester to train them in coding and develop the manuscript. The diet only had minimal effects on the bacterial community profiles, which in this case is a good finding – we want to be able to feed a cheap, nutritional source like distillers’ grains without harming the cow or its microbes.

Dankwa, A.S., U. Humagain, S.L. Ishaq, C.J. Yeoman, S. Clark , D.C. Beitz, and E. D. Testroet. 2021. Determination of the microbial community in the rumen and fecal matter of lactating dairy cows fed on reduced-fat dried distillers grains with solubles. Animal 15(7):100281.

Abstract

Reduced-fat dried distillers’ grains with solubles (RF-DDGS) is a co-product of ethanol production and contains less fat than traditional distillers’ grains. The fat in corn is ~ 91% unsaturated, and it is toxic to rumen microorganisms so it could influence the composition of the rumen microbiome. It has been demonstrated that RF-DDGS is a suitable ration ingredient to support the high-producing dairy cow, and this feedstuff is a promising alternative protein source for lactating dairy cows. The current study aims to better understand the effect of RF-DDGS on the rumen and fecal bacterial composition in lactating dairy cows. Thirty-six multiparous (2 or 3), mid-lactation Holstein cows (BW = 680 ± 11 kg; 106 ± 27 DIM) were randomly assigned to two groups which were fed a control diet made up of corn, corn silage, and alfalfa hay supplemented with expeller soybean meal or with added RF-DDGS (20% of the dry matter (DM)) containing approximately 6.0% fat. Whole rumen contents (rumen fluid and digesta; esophageal tubing method) and feces (free catch method) were collected on day 35 of the experimental period, after the 14-d acclimation period. Rumen contents and feces from each cow were used for DNA extraction. The bacterial community composition in rumen and fecal samples was assessed via the 16S rRNA gene by using the Illumina MiSeq sequencing platform. Bacteroidetes, Actinobacteria, and Firmicutes were the most abundant phyla in rumen contents. The fecal microbiota was dominated by the phyla Firmicutes and Bacteroidetes, as well as Actinobacteria and Chloroflexi. RF-DGGS increased bacterial richness, evenness, and Shannon diversity in both rumen and fecal samples and was associated with several taxa that had different abundance in treatment versus control comparisons.  The RF-DGGS, however, did not significantly alter the bacterial community in the rumen or feces. In general, these findings demonstrated that dietary inclusion of RF-DDGS did not impose any serious short-term (within 30 days) health or production consequences, as would be expected. With this study, we present further evidence that inclusion of 20% (DM basis) RF-DDGS in the diet of lactating dairy cows can be done without consequence on the microbiome of the rumen.

Implications

Reduced-fat dried distillers’ grains with solubles is a quality, economical, and readily available protein source demonstrated to support the protein needs of high-producing dairy cows. In this study, the rumen and fecal bacterial communities of lactating dairy cows were not significantly influenced by 20% (dry matter basis) reduced-fat dried distillers’ grains with solubles and did not impose serious short-term (within 30 days) health or production consequences. This diet could potentially be introduced into Total Mixed Ration feeding of dairy cattle given the fact that it is readily available and relatively economical.

The first MSE symposium was a success!

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Last week, the Microbes and Social Equity working group hosted its first ever symposium! We hosted 15 talks over 5 days, with each session melding presentations and active discussion groups.

In total, the symposium had 254 participants (467 registrants) from 22 countries, and including researchers from various fields and career levels, as well as members of the Maine State Legislation, and members of the general public.  The breakout rooms resulted in 16 draft documents collaboratively written by meeting ideas, which highlight issues/barriers to social equity in research and practice, resources and policy ideas to resolve inequity, research questions yet to be answered, and ideas for curricula development and integrating research and policy into education.

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“Healthcare and the microbiome” at the Microbes and Social Equity virtual symposium, June 18, 2021

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The Microbes and Social Equity working group and The University of Maine Institute of Medicine present an inaugural symposium on:

“Microbes, Social Equity, and Rural Health”

June 14 – 18th, 2021

Format: virtual meeting, Zoom platform.

Day 1 of the Microbes and Social Equity virtual symposium

Session 5: “Access to healthcare and the microbiome”

Friday, June 18th, 13:00 ~ 16:30 EST. Registration for this session is closed.

Section leader: Emily Wissel

Access to healthcare, including treatment and preventative care, is critical to moderate beneficial host-microbe interactions and mitigate host-pathogen interactions, yet healthcare is inequitably distributed and often curbed by social policy. For instance, maternity care is well-demonstrated to improve health outcomes and facilitate the transfer of beneficial maternal microbes to newborns. Policies which support breastfeeding likewise promote this transfer of maternal microbes. Similarly, newborns and infants with access to care in their first five years of life have better outcomes overall than those with limited access. This difference in care during early life can impact lifelong differences in outcomes, reinforcing inequalities present at birth. This session will cover topics from the vaginal microbiome during pregnancy to the infant gut microbiome after birth, with perspectives from a clinician, public health researchers, and a biological scientist.

Program and Registration

Registration, a full speaker list and program, and details of each day can be found here.

Registration will occur for each (day) section individually, so participants can select which topics to participate in, or all of them. 

Registration is free and open to the public.

Summary

Microorganisms are critical to many aspects of biological life, including human health.  The human body is a veritable universe for microorganisms: some pass through but once, some are frequent tourists, and some spend their entire existence in the confines of our body tissues.  The collective microbial community, our microbiome, can be impacted by the details of our lifestyle, including diet, hygiene, health status, and more, but many are driven by social, economic, medical, or political constraints that restrict available choices that may impact our health.   

Many human clinical conditions or diseases have been established as being related  to the state of the human microbiome.  It is known that collective social inequity can drive the prevalence, morbidity, and mortality of some of these diseases or conditions. When access to a nutritious  diet and healthcare are impeded by social inequity, these disparities can also affect the human microbiome; this can further contribute to reduced or poorly functioning microbiomes. 

Access to resources is the basis for creating and resolving social equity—access to healthcare, healthy foods, a suitable living environment, and to beneficial microorganisms, but also access to personal and occupational protection to avoid exposure to infectious disease. The emergence of the SARS-CoV2 (COVID-19) pandemic has dramatically altered our daily lives and the availability and ability to access essential resources, which has been worsened by pre-existing social inequity. Yet, the pandemic has also highlighted the inherent social disparity among those more likely to be exposed to infectious diseases.  

This meeting highlights recent investigations into beneficial and detrimental instances of microbial exposure, in the context of how social policy may mediate or deepen disparities between and within populations. In addition to invited presentations on thematic sections, each section will involve a discussion session using smaller breakout groups, to facilitate conversations and brainstorming between attendees.  These groups will be arranged around smaller themes or research questions, and group members will identify knowledge gaps for future research, as well as list actionable steps that can be taken using existing research to promote equitable social policy.  Ideally, meeting attendees will gain knowledge, collaborators and connections, and a path forward for turning their research into evidence-based policy to support public health.

Meeting dynamics

Unlike traditional symposium formats, this meeting will present some plenary-style talks by experts in the field, including biological scientists, social scientists, practitioners or policy makers, as well as facilitate discussion among participants. Each thematic section will feature 90 minutes of talks, which will be recorded and made publicly available after the live session.  After each plenary session, there will be 90 minutes of discussion in groups led by speakers and MSE group members, and assisted by notetakers, with ~10 participants per breakout room. Participants will be encouraged to “problem solve” a suggested topic or one of their own choosing.  The goal is to create action items that are meaningful for group participants, such as ideas for curricula development, identifying research needs or best practices, suggestions for engaging research in policy, and more.

“Stress and the microbiome” at the Microbes and Social Equity virtual symposium, June 17, 2021

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The Microbes and Social Equity working group and The University of Maine Institute of Medicine present an inaugural symposium on:

“Microbes, Social Equity, and Rural Health”

June 14 – 18th, 2021

Format: virtual meeting, Zoom platform.

Day 1 of the Microbes and Social Equity virtual symposium

Session 4: “Social and Environmental Stress”

Thursday, June 17th, 13:00 ~ 16:30 EST.   Registration for this session is closed.

Section leader: Patricia Wolf

While it has been established that human behavior may impact microbiome structure, it has become evident that this is only part of the story. Historically racist housing policies may lead to inequitable exposure of those living in segregated neighborhoods to environmental pollutants. Additionally, life-long exposure to social and environmental stress faced by minority groups within the US may increase risk to disease through the alteration of host and bacterial metabolites. These inequities were compounded during the COVID-19 pandemic, during which neighborhood structural environments led to differing access to healthcare and treatment for the disease. Notably, those with the least access often were subject to higher exposure to the disease due to having “essential” employment. This session will explore the social and environmental factors that can impact human microbiomes, and will discuss measures that investigators should incorporate into research in order to fully understand microbial mechanisms of disease.

Program and Registration

Registration, a full speaker list and program, and details of each day can be found here.

Registration will occur for each (day) section individually, so participants can select which topics to participate in, or all of them. 

Registration is free and open to the public.

Summary

Microorganisms are critical to many aspects of biological life, including human health.  The human body is a veritable universe for microorganisms: some pass through but once, some are frequent tourists, and some spend their entire existence in the confines of our body tissues.  The collective microbial community, our microbiome, can be impacted by the details of our lifestyle, including diet, hygiene, health status, and more, but many are driven by social, economic, medical, or political constraints that restrict available choices that may impact our health.   

Many human clinical conditions or diseases have been established as being related  to the state of the human microbiome.  It is known that collective social inequity can drive the prevalence, morbidity, and mortality of some of these diseases or conditions. When access to a nutritious  diet and healthcare are impeded by social inequity, these disparities can also affect the human microbiome; this can further contribute to reduced or poorly functioning microbiomes. 

Access to resources is the basis for creating and resolving social equity—access to healthcare, healthy foods, a suitable living environment, and to beneficial microorganisms, but also access to personal and occupational protection to avoid exposure to infectious disease. The emergence of the SARS-CoV2 (COVID-19) pandemic has dramatically altered our daily lives and the availability and ability to access essential resources, which has been worsened by pre-existing social inequity. Yet, the pandemic has also highlighted the inherent social disparity among those more likely to be exposed to infectious diseases.  

This meeting highlights recent investigations into beneficial and detrimental instances of microbial exposure, in the context of how social policy may mediate or deepen disparities between and within populations. In addition to invited presentations on thematic sections, each section will involve a discussion session using smaller breakout groups, to facilitate conversations and brainstorming between attendees.  These groups will be arranged around smaller themes or research questions, and group members will identify knowledge gaps for future research, as well as list actionable steps that can be taken using existing research to promote equitable social policy.  Ideally, meeting attendees will gain knowledge, collaborators and connections, and a path forward for turning their research into evidence-based policy to support public health.

Meeting dynamics

Unlike traditional symposium formats, this meeting will present some plenary-style talks by experts in the field, including biological scientists, social scientists, practitioners or policy makers, as well as facilitate discussion among participants. Each thematic section will feature 90 minutes of talks, which will be recorded and made publicly available after the live session.  After each plenary session, there will be 90 minutes of discussion in groups led by speakers and MSE group members, and assisted by notetakers, with ~10 participants per breakout room. Participants will be encouraged to “problem solve” a suggested topic or one of their own choosing.  The goal is to create action items that are meaningful for group participants, such as ideas for curricula development, identifying research needs or best practices, suggestions for engaging research in policy, and more.

Illustrated image of a cross section of the ground. A light brown ant is pictured in the ground along with a microbe. Text to the left of the image reads, "Can a necromenic nematode serve as a biological Trojan horse for an invasive ant?". The names of six professors are listed below the text and image at the bottom left. In the bottom right corner, text reads, "The University of Maine" with "The University of Arizona" below it.

Paper published on bacterial transfer in insects and possible ecological impacts.

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A collaborative paper on bacterial transfer in insects and the possible ecological impacts of that in the wild has been published in iScience! This work began a decade ago in the labs of Dr. Ellie Groden, recently retired Professor of Entomology in the School of Biology and Ecology at the University of Maine, and later Dr. Patricia Stock, a Professor in the School of Animal and Comparative Biomedical Sciences at the University of Arizona, who were investigating colony collapse of European fire ants (Myrmica rubra) which are invasive to Maine. The ants have a nasty bite, and can dramatically disturb the local plant and insect wildlife in coastal Maine.

Slide from Ishaq et al. Entomology 2020 presentation

When these invasive ant colonies collapsed, Drs. Groden and Stock wanted to find out why, as a possible means of developing a biological control strategy. It was thought that particular nematodes would ingest soil bacteria, and transfer it to ants once the worms invaded ant tissues to complete parts of their life cycle. This particular worm infection doesn’t kill the ants, but perhaps the soil bacteria were. Ants were collected from different colony sites, and investigations on the nematode worms inhabiting the ants were conducted.

Slide from Ishaq et al. Entomology 2020 presentation

Most of the work for this project was completed several years ago, with the exception of DNA sequencing data from a bacterial transfer experiment. I was added to the project by my collaborator at UMaine, Dr. Jean MacRae, an Associate Professor in the Department of Civil and Environmental Engineering who introduced me to the research team and shared the 16S rRNA dataset to use in my AVS 590 data analysis class in spring 2020. That semester was when the pandemic hit, and forced the course to move to remote-only instruction in March. UMaine graduate students Alice Hotopp and Sam Silverbrand were taking the class and learning 16S analysis on this dataset, and I mentored them through the analysis all the way to manuscript writing despite the incredible challenges that spring threw our way.

At the completion of the course, we shared the draft manuscript with the rest of the research team, who mentioned that several undergraduate honor’s theses had been written about the earlier experiment, but never published in a scientific journal. The team spent summer 2020 combining the three papers into one massive draft. The pandemic slowed down manuscript review, understandably, but I’m pleased to say that it was accepted for publication! In addition, this collaboration has led to further collaborations in the Ishaq Lab, several presentations (listed below), and is Sam’s first scientific publication, congrats Sam!!

Related Presentations

Alice Hotopp, A., Samantha Silverbrand, Suzanne L. Ishaq, Jean MacRae, S. Patricia Stock, Eleanor Groden. “Can a necromenic nematode serve as a biological Trojan horse for an invasive ant?” Ecological Society of America 2021 (virtual). Aug 2-6, 2021 (accepted poster).

Ishaq*, S.L., Hotopp, A., Silverbrand, S.,   MacRae, J.,  Stock, S.P.,  Groden, E. “Can a necromenic nematode serve as a biological Trojan horse for an invasive ant?” Entomological Society of America 2020 (virtual). Nov 15-25, 2020. (invited talk)

Illustrated image of a cross section of the ground. A light brown ant is pictured in the ground along with a microbe. Text to the left of the image reads, "Can a necromenic nematode serve as a biological Trojan horse for an invasive ant?". The names of six professors are listed below the text and image at the bottom left. In the bottom right corner, text reads, "The University of Maine" with "The University of Arizona" below it.

Ishaq, S.L., A. Hotopp2, S. Silverbrand2, J.E. Dumont, A. Michaud, J. MacRae, S. P. Stock, E. Groden. 2021. Bacterial transfer from Pristionchus entomophagus nematodes to the invasive ant Myrmica rubra and the potential for colony mortality in coastal Maine. iScience. In press. Impact 5.08.

Abstract

The necromenic nematode Pristionchus entomophagus has been frequently found in nests of the invasive European ant Myrmica rubra in coastal Maine, United States, and may contribute to ant mortality and collapse of colonies by transferring environmental bacteria. Paenibacillus and several other bacterial species were found in the digestive tracts of nematodes harvested from collapsed ant colonies. Serratia marcescens, Serratia nematodiphila, and Pseudomonas fluorescens were collected from the hemolymph of nematode-infected wax moth (Galleria mellonella) larvae.

Virulence against waxworms varied by site of origin of the nematodes. In adult nematodes, bacteria were highly concentrated in the digestive tract with none observed on the cuticle. In contrast juveniles had more on the cuticle than in the digestive tract. .  Host species was the primary factor affecting bacterial community profiles, but Spiroplasma sp. and Serratia marcescens sequences were shared across ants, nematodes, and nematode-exposed G. mellonella larvae.