Regular Paper

Photosynthesis Research

, Volume 107, Issue 3, pp 257-268

First online:

An alphaproteobacterium capable of both aerobic and anaerobic anoxygenic photosynthesis but incapable of photoautotrophy: Charonomicrobium ambiphototrophicum, gen. nov., sp. nov.

  • J. T. CsotonyiAffiliated withDepartment of Microbiology, University of Manitoba
  • , E. StackebrandtAffiliated withDSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
  • , J. SwiderskiAffiliated withDSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
  • , P. SchumannAffiliated withDSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
  • , V. YurkovAffiliated withDepartment of Microbiology, University of Manitoba Email author 

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A facultatively aerobic deep brown coccoid to ovoid bacterium, strain EG17T, was isolated from a saline effluent stream in the NaCl-dominated brine spring system known as East German Creek in the province of Manitoba, Canada. The strain produced BChl a incorporated into a functional reaction center and two light-harvesting complexes with absorption peaks at 802, 850, and 879 nm. EG17T is the first reported anoxygenic phototroph capable of photoheterotrophic growth under both oxic and anoxic conditions. It yielded proportionally the greatest aerobic photosynthetic biomass under oligotrophic conditions. The results of 16S rRNA gene sequence comparisons revealed that EG17T was related most closely to the aerobic anoxygenic phototrophs Roseibacterium elongatum (98.3%) and quite distantly to both Dinoroseobacter shibae (95.2%) and Roseicyclus mahoneyensis (94.7%). The DNA G + C content was 65.6 mol%. On the basis of the unique dual aerobic/anaerobic photosynthetic capability, the distinctive spectrophotometric absorption of the photosynthetic apparatus, diagnostic physiological and biochemical traits, and the moderate phylogenetic separation between EG17T and its nearest relatives, it is concluded that this microorganism should be classified as a novel genus and species, Charonomicrobium ambiphototrophicum gen. nov., sp. nov., with EG17T as the type strain.


Charonomicrobium ambiphototrophicum AAP Aerobic anoxygenic phototorphs Anoxygenic photosynthesis Purple nonsulfur bacteria Photoautotrophy Bacteriochlorophyll a