Archives of Microbiology

, Volume 100, Issue 1, pp 5–24

A phototrophic gliding filamentous bacterium of hot springs, Chloroflexus aurantiacus, gen. and sp. nov.

  • Beverly K. Pierson
  • Richard W. Castenholz

DOI: 10.1007/BF00446302

Cite this article as:
Pierson, B.K. & Castenholz, R.W. Arch. Microbiol. (1974) 100: 5. doi:10.1007/BF00446302


Chloroflexus aurantiacus, gen. and sp. n., is a filamentous phototrophic bacterium of hot springs. On an agar surface, holotype strain J-10-fl glides at 0.01–0.04 μm/sec. The filaments are 0.6–0.7 μm in width and indeterminate in length. Pigments include bacteriochlorophyll c and bacteriochlorophyll a (identified by spectrophotometry) in addition to β and γ-carotene and glycosides of the latter. Chlorobium vesicles are present. Photoheterotrophic growth occurs under anaerobic conditions. Aerobic chemoheterotrophic growth also occurs in darkness or light. Bacteriochlorophyll syntheses cease under aerobic conditions but some types of carotenoids continue to be made. The filament coloration is orange under all except anaerobic conditions in low light intensity where it is dull green. The pH optimum is near 8, the temperature optimum between 52° and 60°C. The DNA base composition for strain J-10-fl is 54.9 ± 1.0 moles % guanine + cytosine. Chloroflexus is unique in that there have been no previous reports of filamentous or gliding phototrophic bacteria. The combinations of bacteriochlorophylls a and c and the presence of chlorobium vesicles in a photoheterotroph and in an organism capable of aerobic growth are also unique. This metabolically versatile organism extends the taxonomic and phylogenetic limits of the “green line” of phototrophic bacteria.

Key words

Chloroflexus Thermophilic Photosynthetic Bacterium Filamentous Gliding Bacteriochlorophyll Chlorobium Vesicles Photoheterotrophic 

Copyright information

© Springer-Verlag 1974

Authors and Affiliations

  • Beverly K. Pierson
    • 1
  • Richard W. Castenholz
    • 1
  1. 1.Department of BiologyUniversity of OregonEugene