OSU researchers discover unprecedented diversity of anaerobic fungi in herbivores

Friday, June 30, 2023

Media Contact: Harrison Hill | Senior Research Communications Specialist | 405-744-5827 | harrison.c.hill@okstate.edu

An innovative study has revealed remarkable insights into the diversity and evolution of anaerobic gut fungi in herbivorous animals. These fungi live in environments without oxygen, so little is known about their distribution patterns, host range and diversity.

However, that knowledge has grown significantly thanks to a research project led by Drs. Mostafa Elshahed and Noha Youssef, professors in the department of Microbiology and Molecular Genetics. 

“We have always been fascinated by these interesting critters,” Elshahed said. “These anaerobic gut fungi play a crucial role in host nutrition by breaking down plant material into simpler products.”

The research group consisted of a team of OSU scientists — including graduate students Casey Meili, Adrienne Jones and Carrie Pratt from the Department of Microbiology and Molecular Genetics, and Dr. Andrew Foote, a professor in the Department of Animal and Food Science —as well as scientists from 17 institutions in 12 countries.

With funding from the National Science Foundation Division of Environmental Biology Systematics and Biodiversity Sciences their goal was to examine the global diversity of these fungi and understand some of the factors — both ecological and evolutionary — that influence gut microbial communities.  

The study, titled "Patterns and determinants of the global herbivorous mycobiome" was recently published in Nature Communications. 

“This study ended up revealing 56 previously undiscovered fungal genera,” Youssef said. “This doubles the known anaerobic fungal diversity uncovered over the past 50 years of research.”

Hundreds of fecal samples were obtained from 34 species of plant-eating animals. These samples allowed the group to analyze DNA sequences using a variety of computational tools that highlighted the fungal diversity and community structure without the need to grow the fungi in the lab.  

Beyond documenting the occurrence of novel fungi, the team also used the data set to understand patterns of fungal distribution in their hosts. 

“We uncovered an interesting pattern where animals that are more genetically related to each other (for example goats and sheep or horses and mules) harbor a collection of fungi that are also more similar to each other than to the communities in less related hosts,” Elshahed said. “On the other hand, domestication, geography, and diet appear to play more minor roles in determining the gut fungal community.” 

By combining genomics and fossil dating with these ecological insights, the researchers uncovered an interesting evolutionary phenomenon: many fungal genera appear to have co-evolved with their preferred animal hosts. For example, the evolution of the horse family Equidae occurred at roughly the same time (55 million years ago) as the emergence of their preferred fungal genus Khoyollomyces.  

 “It appears that fungi and animals that evolve together stay together,” Youssef said. “Such evolutionary-based associations appear to be retained today meaning that by looking at present ecological distribution patterns, we could begin to better understand the evolutionary relationships of the past.” 

The identification of these novel genera and the understanding of their evolutionary history have far-reaching implications for future studies on anaerobic fungi and the development of targeted interventions for animal health and nutrition.  

With isolation efforts currently underway, the researchers are hopeful they will be able to learn more about the functional role of these fungi.  

The novel enzymes and antibiotics produced by these organisms could be utilized in biotechnology, agriculture and health.