New CCI bioinformatics research helps explain key role of protists in modern analogs to ancient microbial ecosystems

UNC Charlotte Assistant Professor of Bioinformatics Dr. Richard Allen White III, faculty in the College of Computing and Informatics and the North Carolina Research Campus, has published new research explaining how microscopic protist organisms and tiny animals called metazoans affect the growth and health of modern microbialites, which are modern versions of ancient ecosystems that form “living rock” organic structures containing illuminating information about life on Earth as far back as 3.45 billion years.

This study, published in scientific journal NPJ Biofilms and Microbiomes, was led by White and fellow microbiologists Dr. Anthony M. Bonacolta and Dr. Javier del Campo (University of Miami), alongside Dr. Pieter Visscher (University of Connecticut). Their analysis reached around the entire world, focusing on the freshwater Kelly Lake and Pavilion Lake in British Columbia, the marine Highborne Cay in the Bahamas, and the hypersaline Shark Bay in Australia.

“It’s been a long time coming, but we have finally illuminated the diversity and the potential roles of protists and metazoans in freshwater modern microbialites and have directly compared them to marine and hypersaline microbialites,” said White. “Freshwater microbialites are less studied than marine and hypersaline microbialites, especially for protists, metazoans, fungi, viruses, and bacteriophage,” said White. “Our group with excellent collaborators such as Dr. Visscher and Dr. Del Campo finally have revealed these communities to all,” said White. 

White and his collaborators explain the important part protists play in the life of microbialites by contributing to photosynthesis, grazing on bacterial communities, and producing the carbon-based exopolymeric substances (EPS) that help form and stabilize the sediment structures that compose modern microbialites. 

Modern microbialites house a wide diversity of eukaryotes, the diversity of which is impacted by salinity. Salinity appears to be a main driver of the protist community composition and structure in modern microbialites globally. Formation of modern microbialites are directly impacted by the abiotic processes of light and salinity. Even with this varying amount of salinity, varying protists occupy niches within the microbialite communities to provide various different roles, including building through photosynthesis or grazing. While the researchers found that the exact types of protists and metazoans present in different bodies of water differ significantly based on the water’s salt level, with a higher abundance of chlorophytes including green eukaryotic algae in freshwater compared to the overall higher abundance of diatoms in marine environments. 

Microbialites are made of either pure calcium carbonate or magnesium carbonates that trap carbon dioxide from the atmosphere and transform it into stone. Beyond their roles as analogs to the earliest microbial ecosystems, their functional role may help us learn how to bank carbon in the form of stone that could be used in modern building materials or other applications. 

“Microbialites give us a model system for proxies into how life assembled in its earliest forms, with the hope that it will give us some insight into the rules of life as we know it,” said White. 

Read the full article here: https://www.nature.com/articles/s41522-024-00547-z