Chloroflexus is a genus of green nonsulfur bacteria in the family Chloroflexaceae. They are photosynthetic (using or formed by photosynthesis), thermophilic (growing best at elevated temperatures from 35°C to 70°C), filamentous (thin in diameter and resembling a thread) gliding bacteria found in hot springs. Chloroflexus aurantiacus can survive in the dark if oxygen is available. When grown in the dark, it has a dark orange color. When grown in sunlight, it is dark green. These bacteria tend to form colonies and are unique in that they lack Calvin cycle, as well as the reverse TCA cycle. The main pigments in Chloroflexus are large aggregates of bacteriochlorophyll-c and carotenoids.2

Synechococcus (rod-like cells, 1.2 µm wide), some dividing, and Chloroflexus aurantiacus trichomes
Source: PubMed Central

Chloroflexus aurantiacus is a filamentous anoxygenic phototrophic bacterium isolated from hot springs. It has specialized light-harvesting antenna machines which can convert light energy into ATP via photosynthetic electron transfer. In its natural habitat, C. aurantiacus consumes organic nutrients (short-chain fatty acids, acetate, etc.) released from cyanobacteria in the associated microbial mats.3


  1. Bacteriologists: Webster's Quotations, Facts and Phrases. Inc Icon Group International
  2. Microbial diversity: Form and function in prokaryotes. Oladele Ogunseitan
  3. Glycine Cleavage Powers Photoheterotrophic Growth of Chloroflexus aurantiacus in the Absence of H2. Lian He,1 Yaya Wang,2 Le You,1 Yadana Khin,2 Joseph K.-H. Tang,2,3,* and Yinjie J. Tang1,* Front Microbiol. 2015; 6: 1467.



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