'Candidatus Viridifilum namsaraevi' gen. nov., sp. nov., a new mesophilic filamentous anoxygenic phototrophic bacterium from the mesothermal lake Umkhey (Buryatia).

A novel mesophilic filamentous phototrophic bacterium, 'Candidatus Viridifilum namsaraevi', was identified from Lake Umkhey, revealing unique metabolic features within Chloroflexota.

• Why it matters: Understanding the evolution of phototrophy and carbon fixation in Chloroflexota is limited by the scarcity of cultured mesophilic representatives, hindering insights into their metabolic diversity and evolutionary history.
• What they did: Researchers reconstructed the genome of this bacterium from environmental samples using metagenomics, analyzing its phylogenetic position and metabolic pathways, including CO2 fixation and sulfur metabolism.
• The result: The findings expand knowledge of Chloroflexota evolution, highlighting metabolic adaptations and providing a genomic reference that informs studies of microbial evolution and ecology in sulfide-rich, alkaline environments.