Definition
Chloroflexota is a bacterial phylum comprising a diverse group of Gram‑negative, filamentous bacteria, many of which are capable of anoxygenic photosynthesis and are often referred to as “green non‑sulfur bacteria.”
Overview
Members of the phylum Chloroflexota are found in a variety of environments, including hot springs, marine sediments, soils, and wastewater treatment systems. The phylum includes both phototrophic and non‑phototrophic lineages; phototrophic species typically possess bacteriochlorophyll a and perform photosynthesis without producing oxygen. Several genera, such as Chloroflexus and Roseiflexus, are thermophilic and thrive at temperatures up to 70 °C. The phylum also contains heterotrophic representatives that degrade organic compounds under aerobic or anaerobic conditions.
Etymology / Origin
The name “Chloroflexota” derives from the Greek words chloros (“green”) and flexus (“bent” or “flexible”), referring to the characteristic green pigmentation and filamentous morphology of many members. The suffix “‑ota” is a standard taxonomic ending used for bacterial phyla. The phylum was formerly known as Chloroflexi; the updated name aligns with recent conventions in prokaryotic nomenclature.
Characteristics
- Cell morphology: Typically filamentous, with cells arranged in long, flexible threads; some species form bundles or mats.
- Cell wall structure: Gram‑negative cell envelope with an outer membrane containing lipopolysaccharide.
- Metabolism:
- Phototrophic members: Conduct anoxygenic photosynthesis using bacteriochlorophyll a; do not evolve O₂ and often use light‑induced electron transport for carbon fixation.
- Chemotrophic members: Aerobic or anaerobic heterotrophs that oxidize organic substrates such as carbohydrates, fatty acids, and aromatic compounds.
- Ecophysiology: Many are thermophiles or moderate thermophiles; some are alkaliphilic or halotolerant.
- Genomic features: Genomes range from ~3 to >5 Mbp; they encode photosynthetic reaction‑center proteins (puf genes) in phototrophic lineages and a variety of enzymes for carbohydrate and lipid metabolism in heterotrophs.
- Ecological roles: Contribute to carbon cycling in hot‑spring microbial mats, participate in the degradation of organic pollutants, and serve as model organisms for studying the evolution of photosynthesis.
Related Topics
- Chloroflexus – a genus of thermophilic, filamentous, anoxygenic phototrophs within Chloroflexota.
- Anoxygenic photosynthesis – a photosynthetic process that does not produce molecular oxygen.
- Thermophilic bacteria – microorganisms that grow optimally at elevated temperatures.
- Bacterial taxonomy – the classification system for prokaryotic organisms, including recent revisions of phylum names.
- Microbial mats – multilayered communities of microorganisms, often dominated by Chloroflexota in hot‑spring environments.