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Study Highlights Diversity of the Gut Microbiome in Gorillas

A western lowland gorilla looks toward the camera.
Photo credit: Dušan veverkolog.

For Immediate Release

Erin McKenney

A new study led by North Carolina State University and the Denver Zoo sheds light on the gut microbiome of gorillas, moving researchers closer to developing tools that can use the microbiome to diagnose potential health challenges for gorillas in human care. Specifically, the study found significant diversity among gorilla microbiomes, suggesting that what constitutes a “healthy” microbiome can vary between individuals.

The gut microbiome refers to the ecosystem of microbial organisms that exist in the gastrointestinal tract of animals. Research has found that the type and number of microbes present can significantly impact an animal’s health and well-being.

“Longitudinal data sets that characterize a gut microbiome over time can be hugely useful for establishing what a healthy normal is, which can help us determine when things are out of balance and may affect an animal’s health,” says Erin McKenney, co-author of the study and an assistant professor of applied ecology at NC State. “Our work here is currently the longest-term, most heavily sampled dataset that captures what healthy gut microbiomes look like in gorillas that are under human care.”

“And yet we feel this is really just the tip of the iceberg,” says Kimberly Ange-van Heugten, corresponding author of the study and an associate professor of animal science at NC State. “We’re finding that the more we learn, the more we appreciate how much there is still to learn about the relationship between gut microbiomes and health in gorillas.”

For this study, a team of researchers from half a dozen institutions worked together to better understand how the gut microbiomes of western lowland gorillas (Gorilla gorilla gorilla) vary across individuals, across different institutions, and over time.

“It’s important to look at gorillas at different institutions because zoos often have different management protocols – they may provide gorillas with different diets, housing, access to outdoor space, and so on,” McKenney says. “All of these factors could potentially influence a gorilla’s gut microbiome.”

To that end, the research team collected fecal samples from 19 gorillas in human care at three institutions: six at the Denver Zoo, five at the Riverbanks Zoo, and eight at the North Carolina Zoo. The ages of the gorillas ranged from 2 to 45. Samples were collected every two weeks for seven months. The researchers then analyzed the samples to determine which microbes were present in each sample, and in what amounts.

The researchers detected profound differences in the complexity of the microbial communities found in individual gorillas, in terms of which kinds of microbes were present, how many kinds of microbes were present, and the relative abundance of the different types of microbes present. These differences could not be linked primarily to diet or other variables.

“In other words, the microbial differences between two gorillas were not driven primarily by variations between institutions; we found minor differences related to environmental variables, but not substantial ones,” McKenney says.

“That means two gorillas could both be healthy and yet have very different microbiomes,” Ange-van Heugten says. “That suggests it is important to understand what an individual gorilla’s healthy microbiome looks like in order to detect changes that could indicate a health problem.”

Previous studies have documented variation among individuals, across a variety of species.

“But long-term studies, like this one, help us identify how those differences relate to health, if at all,” McKenney says. “Our research emphasizes the importance of understanding what ‘healthy’ means across individuals, over time, for any population or species of interest.”

“We looked only at gorillas that are in human care, not at wild populations,” Ange-van Heugten says. “But our findings highlight that even if free-ranging gorillas and gorillas in human care have different microbiomes, that doesn’t necessarily mean one population is healthy and one isn’t. We need longitudinal studies from many populations of healthy animals to understand more about what constitutes a ‘normal’ microbiome for a species or an individual.”

“It’s interesting that previous studies of humans also detected microbial profiles that differ between individuals but remain fairly consistent over time,” McKenney says. “This suggests that individual context may be important at least across primates – and perhaps across all different species. Obviously a lot of additional work is needed to explore that possibility, but it’s very exciting.”

The paper, “Host Identity and Geographic Location Significantly Affect Gastrointestinal Microbial Richness and Diversity in Western Lowland Gorillas (Gorilla gorilla gorilla) Under Human Care,” is published open access in the journal Animals. First author of the paper is Katrina Eschweiler, a former graduate student at NC State who is now at the Denver Zoo. The paper was co-authored by Jonathan Clayton of the University of Nebraska at Omaha and the University of Nebraska-Lincoln; Anneke Moresco was at the Denver Zoo and is also an adjunct faculty member at NC State; Larry “Jb” Minter of the North Carolina Zoo and is also an adjunct faculty member at NC State; Mallory Suhr Van Haute of the University of Nebraska-Lincoln; William Gasper, Shivdeep Singh Hayer and Kathryn Cooper of the University of Nebraska at Omaha; and Lifeng Zhu of Nanjing Normal University.

The work was conducted with partial support from the Primate Microbiome Project at the University of Nebraska-Lincoln.

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Note to Editors: The study abstract follows.

“Host Identity and Geographic Location Significantly Affect Gastrointestinal Microbial Richness and Diversity in Western Lowland Gorillas (Gorilla gorilla gorilla) Under Human Care”

Authors: Katrina Eschweiler, North Carolina State University and Denver Zoo; Jonathan Clayton, University of Nebraska at Omaha and University of Nebraska-Lincoln; Anneke Moresco, Denver Zoo, North Carolina State University; Erin McKenney and Kimberly Ange-van Heugten, North Carolina State University; Larry “Jb” Minter, North Carolina Zoo and North Carolina State University; Mallory Suhr Van Haute, University of Nebraska-Lincoln; William Gasper, Shivdeep Singh Hayer and Kathryn Cooper, University of Nebraska at Omaha; and Lifeng Zhu, Nanjing Normal University

Published: Nov. 28, Animals

DOI: 10.3390/ani11123399

Abstract: The last few decades have seen an outpouring of gastrointestinal (GI) microbiome studies across diverse host species. Studies have ranged from assessments of GI microbial richness and diversity to classification of novel microbial lineages. Assessments of the “normal” state of the GI microbiome composition across multiple host species has gained increasing importance for distinguishing healthy versus diseased states. This study aimed to determine baselines and trends over time to establish “typical” patterns of GI microbial richness and diversity, as well as inter-individual variation, in three populations of western lowland gorillas (Gorilla gorilla gorilla) under human care at three zoological institutions in North America. Fecal samples were collected from 19 western lowland gorillas, every two weeks, for seven months (n=248). Host identity and host institution significantly affected GI microbiome community composition (p<0.05), although host identity had the most consistent and significant effect on richness (p=0.03) and Shannon diversity (p=0.004) across institutions. Significant changes in microbial abundance over time were observed only at Denver Zoo (p<0.05). Our results suggest that individuality contributes to most of the observed GI microbiome variation in the study populations. Our results also showed no significant changes in any individual’s microbial richness or Shannon diversity during the 7-month study period. While some microbial taxa (Prevotella, Prevotellaceae and Ruminococcaceae) were detected in all gorillas at varying levels, determining individual baselines for microbial composition comparisons may be the most useful diagnostic tool for optimizing non-human primate health under human care.

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