Introducing the Microbes and Social Equity Working Group: considering the microbial components of social, environmental, and health justice.

The Microbes and Social Equity Working Group was founded in early 2020 by Sue Ishaq, as interest grew following her publication in fall of 2019, “Framing the discussion of microorganisms as a facet of social equity in human health.”

In summer 2021, MSE group membership blossomed to ~ 90 members from around the globe, and “members represent diverse fields, e.g., anthropology, architecture, bioethics, bioinformatics, data science, ecology, engineering, genetics, medicine, microbiology, nutrition, psychology, and sociology, and exhibit expertise in various hosts, systems, and environments beyond human microbiomes. We are researchers, educators, practitioners, and policymakers spanning the globe and career levels.” (Ishaq et al. 2021).

In this publication, 35 of us collaboratively wrote our Mission Statement, our primary objectives, and introduced the group to the world!

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 JusticemSystems 6:4.

Part of the mSystems Special Series: Social Equity as a Means of Resolving Disparities in Microbial Exposure


Humans are inextricably linked to each other and our natural world, and microorganisms lie at the nexus of those interactions. Microorganisms form genetically flexible, taxonomically diverse, and biochemically rich communities, i.e., microbiomes that are integral to the health and development of macroorganisms, societies, and ecosystems. Yet engagement with beneficial microbiomes is dictated by access to public resources, such as nutritious food, clean water and air, safe shelter, social interactions, and effective medicine. In this way, microbiomes have sociopolitical contexts that must be considered. The Microbes and Social Equity (MSE) Working Group connects microbiology with social equity research, education, policy, and practice to understand the interplay of microorganisms, individuals, societies, and ecosystems. Here, we outline opportunities for integrating microbiology and social equity work through broadening education and training; diversifying research topics, methods, and perspectives; and advocating for evidence-based public policy that supports sustainable, equitable, and microbial wealth for all.

Logo designed by Alex Guillen

Determination of the microbial community in the rumen and fecal matter of lactating dairy cows fed on reduced-fat dried distillers grains with solubles.

Ruminants, like sheep, goats, cows, deer, moose, etc.,  have a four-chambered stomach, the largest of which is called the rumen.  The rumen houses symbiotic microorganisms which break down plant fibers that the animal can’t digest on its own.  It’s estimated that up to 80% of a ruminant’s energy need is met from the volatile fatty acids (also called short-chain fatty acids) that bacteria produce from digesting fiber, and that up to 85% of a ruminant’s protein need is met from microbial proteins.

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.


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.


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.

Bacterial transfer from Pristionchus entomophagus nematodes to the invasive ant Myrmica rubra and the potential for colony mortality in coastal Maine.

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)


UMaine researchers want to use nematodes to kill fire ants.”, Julia Bayly, Bangor Daily News, July 29, 2021.

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

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.

IshaqS.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.


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. 

Temporal soil bacterial community responses to cropping systems and crop identity in dryland agroecosystems of the Northern Great Plains.

This project was part of the graduate research for master’s student Tindall Ouverson, and is her first manuscript!

Photo of woman in front of mountains

Tindall is a Master’s of Science in the Department of Land Resources and Environmental Sciences at Montana State University. Her graduate advisers are Drs. Fabian Menalled and Tim Seipel. Her research focuses on the response of soil microbial communities to cropping systems and climate change in semiarid agriculture. 

I have been mentoring Tindall as a graduate committee member since she began in fall 2019, teaching her laboratory and analytical skills in microbial ecology, DNA sequencing, and bioinformatic analysis. We first met when she came to visit when I was working in Oregon, and since then have connected remotely. She has a flair for bioinformatics analysis, and a passion for sustainable agricultural development. She plans to defend her thesis in spring 2021, and then to further her career in sustainable agriculture in Montana.

In the Northern Great Plains of the United States, cereal crops, such as wheat, are important economic staples. In this area, climate change is forecasted to increase temperature and decrease precipitation during the summer, which is expected to negatively affect crop production and the management of pests (insects and microbes).  There are numerous reports on the current effects of climate change on agricultural production, as well as how they will be predicted to worsen, such as:

Ouverson, T.,  Eberly, J., Seipel, T., Menalled, F., Ishaq, S.L.2021.Temporal soil bacterial community responses to cropping systems and crop identity in dryland agroecosystems of the Northern Great Plains.  Frontiers in Sustainable Food Systems 5:75No Impact Factor. Article. This is an invited submission to Plant Growth-Promoting Microorganisms for Sustainable Agricultural Production  special collection.


Industrialized agriculture results in simplified landscapes where many of the regulatory ecosystem functions driven by soil biological and physicochemical characteristics have been hampered or replaced with intensive, synthetic inputs. To restore long-term agricultural sustainability and soil health, soil should function as both a resource and a complex ecosystem. In this study, we examined how cropping systems impact soil bacterial community diversity and composition, important indicators of soil ecosystem health. Soils from a representative cropping system in the semi-arid Northern Great Plains were collected in June and August of 2017 from the final phase of a five-year crop rotation managed either with chemical inputs and no-tillage, as a USDA-certified organic tillage system, or as a USDA-certified organic sheep grazing system with reduced tillage intensity. DNA was extracted and sequenced for bacteria community analysis via 16S rRNA gene sequencing. Bacterial richness and diversity decreased in all farming systems from June to August and was lowest in the chemical no-tillage system, while evenness increased over the sampling period. Crop species identity did not affect bacterial richness, diversity, or evenness. Conventional no-till, organic tilled, and organic grazed management systems resulted in dissimilar microbial communities. Overall, cropping systems and seasonal changes had a greater effect on microbial community structure and diversity than crop identity. Future research should assess how the rhizobiome responds to the specific phases of a crop rotation, as differences in bulk soil microbial communities by crop identity were not detectable.

Framing the discussion of microorganisms as a facet of social equity in human health

In summer 2019, I developed and taught a course on ‘Microbes and Social Equity‘ to the Clark Honors College at the University of Oregon.

In just a four-week course, I introduced 15 undergraduates from the University of Oregon Clark Honors College to microorganisms and the myriad ways in which we need them. More than that, we talked about how access to things, like nutritious foods (and especially fiber), per- and postnatal health care, or greenspace and city parks, could influence the microbial exposures you would have over your lifetime. Inequalities in that access – such as only putting parks in wealthier neighborhoods – creates social inequity in resource distribution, but it also creates inequity in microbial exposure and the effect on your health.

The course assignments were literature review essays on various topics, which were compiled into a single manuscript as the group-based final project for the course. This large version is available as a preprint; however, the published version is more focused (abstract below). Course materials are here.

What is next for ‘Microbes and Social Equity’?

Since publishing in November, a number of researchers have connected with me, and we have formed a loose collaboration for “Microbes and Social Equity Part 2”. We have several initiatives in development, and there will be news releases as those coalesce. At this time, we are developing a journal special call, and a series of workshops/mini-symposia, both with the goal of connecting researchers and practitioners. Stay tuned!

Framing the discussion of microorganisms as a facet of social equity in human health.

Suzanne L. Ishaq1,2*, Maurisa Rapp2,3, Risa Byerly2,3, Loretta S. McClellan2, Maya R. O’Boyle2, Anika Nykanen2, Patrick J. Fuller2,4, Calvin Aas2, Jude M. Stone2, Sean Killpatrick2,4, Manami M. Uptegrove2, Alex Vischer2, Hannah Wolf2, Fiona Smallman2, Houston Eymann2,5, Simon Narode2, Ellee Stapleton6, Camille C. Cioffi7, Hannah Tavalire8

  1. Biology and the Built Environment Center,  University of Oregon
  2. Robert D. Clark Honors College, University of Oregon
  3. Department of Human Physiology, University of Oregon
  4. Charles H. Lundquist College of Business, University of Oregon
  5. School of Journalism and Communication, University of Oregon
  6. Department of Landscape Architecture, University of Oregon
  7. Counseling Psychology and Human Services, College of Education, University of Oregon
  8. Institute of Ecology and Evolution, University of Oregon


What do ‘microbes’ have to do with social equity? On the surface, very little. But these little organisms are integral to our health, the health of our natural environment, and even impact the ‘health’ of the environments we have built. Early life and the maturation of the immune system, our diet and lifestyle, and the quality of our surrounding environment can all impact our health. Similarly, the loss, gain, and retention of microorganisms ⁠— namely their flow from humans to the environment and back⁠ — can greatly impact our health and well-being. It is well-known that inequalities in access to perinatal care, healthy foods and fiber, a safe and clean home, and to the natural environment can create and arise from social inequality. Here, we focus on the argument that access to microorganisms as a facet of public health, and argue that health inequality may be compounded by inequitable microbial exposure.

In the Media

  1. ” UMaine prof: Inequity is creating a gut microbe gap.” Mike Tipping and Ben Chin, Maine People’s Alliance. Dec 20, 2019.
  2. Inequity takes a toll on your gut microbes, too.” Sue Ishaq,  The Conversation, Dec 4, 2019.
    1. Picked up by The Telegraph, Alton, Illinois, and other agencies
    2. Included on UMaine news
  3. All people have a right to healthy gut microbes.” Paige Jarreau and Signe Asberg, Lifeapps. Dec 3, 2019.  
  4. Rich People Have Access to Better Microbes Than Poor People, Researchers Say.” Becky Ferreira, Vice. Nov 26, 2019.
  5. Microbiome is a Human Right.” Heather Smith, Sierra. Nov 26, 2019.
  6. Life, liberty—and access to microbes?” Press release for Plos Biology. Nov 19, 2019.

Story picked up by (non-exhaustive list)