Temperature impacts community structure and function of phototrophic Chloroflexi and Cyanobacteria in two alkaline hot springs in Yellowstone National Park

Temperature plays a key role in shaping the distribution and activity of phototrophic Chloroflexi alongside Cyanobacteria in alkaline hot springs, challenging previous assumptions that only temperature constrains these microbial communities. While phototrophic Cyanobacteria richness and oxygenic photosynthesis declined with increasing temperature, Chloroflexi maintained diversity and anoxygenic photosynthetic rates even at near the upper thermal limits (~72-73°C). This suggests niche differentiation among Chloroflexi taxa, potentially influenced by factors beyond temperature such as morphology or metabolic pathways. The study used 16S rRNA gene sequencing and photoassimilation microcosms to analyze samples from 45 to 72°C in two Yellowstone hot springs, revealing distinct temperature-driven distributions for Roseiflexus, Chloroflexus (Chloroflexi), and Leptococcus (Cyanobacteria). Carbon isotopic data further indicated shifting metabolic pathways with temperature. These findings highlight the resilience and adaptability of phototrophic Chloroflexi in extreme environments.

Bennett, A. C., Murugapiran, S. K., & Hamilton, T. L. (2020). Temperature impacts community structure and function of phototrophic Chloroflexi and Cyanobacteria in two alkaline hot springs in Yellowstone National Park. Environmental Microbiology Reports, 12(5), 503–513. Portico. https://doi.org/10.1111/1758-2229.12863