The Chloroflexi are a class of bacteria that produce energy from light. They make up the bulk of the filamentous anoxygenic phototrophs (formerly known as green non-sulfur bacteria), though some are classified separately as the Thermomicrobia.^{[1] [2]} They are named for their green pigment, usually found in photosynthetic bodies called chlorosomes.

Chloroflexi are typically filamentous, and can move about through bacterial gliding. They are facultatively aerobic, but do not produce oxygen in the process of producing energy from light, or phototrophy. Additionally Chloroflexi have a different method of phototrophy (photoheterotrophy) than true photosynthetic bacteria. Phylogenetic analysis indicates that they had a separate origin.

Photo: Chloroflexus photomicrograph from the Joint Genome Institute of the United States Department of Energy