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Title: Nutrient requirements and growth physiology of the photoheterotrophic Acidobacterium, Chloracidobacterium thermophilum

A novel thermophilic, microaerophilic, anoxygenic, and chlorophototrophic member of the phylum Acidobacteria, Chloracidobacterium thermophilum strain BT, was isolated from a cyanobacterial enrichment culture derived from microbial mats associated with Octopus Spring, Yellowstone National Park, Wyoming. C. thermophilum is strictly dependent on light and oxygen and grows optimally as a photoheterotroph at irradiance values between 20 and 50 µmol photons m⁻² s⁻¹. C. thermophilum is unable to synthesize branched-chain amino acids (AAs), L-lysine, and vitamin B₁₂, which are required for growth. Although the organism lacks genes for autotrophic carbon fixation, bicarbonate is also required. Mixtures of other AAs and 2-oxoglutarate stimulate growth. As suggested from genomic sequence data, C. thermophilum requires a reduced sulfur source such as thioglycolate, cysteine, methionine, or thiosulfate. The organism can be grown in a defined medium at 51° C (Topt; range 44–58°C) in the pH range 5.5–9.5 (pHopt = ~7.0). Using the defined growth medium and optimal conditions, it was possible to isolate new C. thermophilum strains directly from samples of hot springs mats in Yellowstone National Park, Wyoming. The new isolates differ from the type strain with respect to pigment composition, morphology in liquid culture, and temperature adaptation.
 [1] ;  [2]
  1. The Pennsylvania State Univ., University Park, PA (United States). Dept. of Biochemistry and Molecular Biology
  2. The Pennsylvania State Univ., University Park, PA (United States). Dept. of Biochemistry and Molecular Biology; Montana State Univ., Bozeman, MT (United States). Dept. of Chemistry and Biochemistry
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Frontiers in Microbiology
Additional Journal Information:
Journal Volume: 06; Journal Issue: 5; Journal ID: ISSN 1664-302X
Frontiers Research Foundation
Research Org:
The Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org:
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES bacteriochlorophyll; anoxygenic photosynthesis; photoheterotroph; thermophile; Acidobacteria