Two Bacterial Species from Hot Springs Cooperate to Colonize New Niches

A study of two species of thermophilic bacteria found in hot springs from Yellowstone National Park reveals that microbial cooperation not only enhances motility towards light, but also the colonization of new niches and construction of stronger biofilms.

May 22, 2025

A study of two types of bacteria in Yellowstone hot springs revealed an unexpected level of cooperation between distantly related microbes that may enable them to survive in challenging environments. (Image by Freddy Bunbury | University of Chicago)

The Science

Microbial mats are layered microbial communities that thrive in many places, including in extreme environments like the hot springs at Yellowstone National Park. These mats include diverse organisms that interact in complex ways; however, how their structure and behavior respond to environmental cues, such as light, is not fully understood. As part of a multi-institutional study, researchers isolated a unicellular Synechococcus species and a filamentous Chloroflexus species from these mats and observed their movement and biofilm formation. When combined, the two species had coordinated movement toward light and formed more structured and robust biofilms than either species alone. These findings reveal an unexpected level of cooperation between distantly related microbes that may enable them to survive more readily in challenging environments.

The Impact

This work challenges a view of microbial mats in hot springs as static assemblages by demonstrating that microbial interactions can lead to dynamic, light-responsive behavior. Instead, the findings suggest that physical and behavioral cooperation between microbial species enhances collective motility and structural organization. This insight has broader implications for understanding microbial ecology in biofilms, and it could inform strategies for engineering synthetic microbial consortia with applications in environmental biotechnology.

Summary

Diagram showing Chloroflexota species on the left, Cyanobacteria species on the right and both species together in between them. — Three colonies of bacterial isolates from hot springs at Yellowstone National Park moving over moist agar in the presence of light. The isolate of Chloroflexus species (Chloroflexota [magenta]) moves in all directions relative to the light, while the isolate of Synechococcus species (Cyanobacteria [green]) moves toward the light. Together, a mixture of both species (middle) moves further toward the light more than either does alone. (Image by Freddy Bunbury | University of Chicago)

Microbial mats exhibit complex organization and dynamic responses to environmental gradients. To dissect the role of species interactions in these processes, a multi-institutional team studied a two-member model consortium consisting of the unicellular, phototrophic cyanobacterium Synechococcus OS-B′ (Syn OS-B′), and the filamentous phototroph Chloroflexus MS-CIW-1 (Chfl MS-1). Single-species assays revealed that Chfl MS-1 exhibited non-directional filamentous motility, while Syn OS-B′ moved towards a light source (directional phototaxis). When combined, the two species moved cooperatively toward light and made well-organized biofilms that adhered more strongly to surfaces than either species alone. This cooperative behavior was abolished in a mutant of Syn OS-B′ that lacked motility, highlighting the importance of cyanobacterial movement in driving collective microbial behavior. Using advanced microscopy available at the Environmental Molecular Sciences Laboratory (EMSL), a Department of Energy Office of Science user facility at Pacific Northwest National Laboratory, the team discovered that the two species have a tight physical association within the biofilm matrix, and this may be the basis for the coordinated movement and stronger biofilms. These findings advance understanding of complex microbial behaviors and their contributions to the stability and function of natural mats.

Contacts

Freddy Bunbury | University of Chicago | Freddy.bunbury@gmail.com

Devaki Bhaya | Carnegie Institution for Science | dbhaya@carnegiescience.edu

Amar Parvate | EMSL | amar.parvate@pnnl.gov

Funding

This research was supported by the University of Chicago, Carnegie Institution for Science, and a Biotechnology and Biological Sciences Research Council-National Science Foundation Directorate for Biological Sciences collaborative research grant. Additional support was provided by the Department of Energy (DOE) Biological and Environmental Research program (BER) and the National Institutes of Health. A portion of the research was performed on an Exploratory award from EMSL, a DOE Office of Science user facility sponsored by BER.

Publication

F. Bunbury, et al. “Cyanobacteria and Chloroflexota cooperate to structure light-responsive biofilms.” Proceedings of the National Academy of Sciences. 122 (5) e2423574122 (2025). [DOI: 10.1073/pnas.2423574122]