Archives of Microbiology

, Volume 128, Issue 4, pp 365–370

Thermobacteroides acetoethylicus gen. nov. and spec. nov., a new chemoorganotrophic, anaerobic, thermophilic bacterium

  • Arie Ben-Bassat
  • J. G. Zeikus

DOI: 10.1007/BF00405914

Cite this article as:
Ben-Bassat, A. & Zeikus, J.G. Arch Microbiol (1981) 128: 365. doi:10.1007/BF00405914


The taxonomic and metabolic characteristics of a new caldoactive bacterium, Thermobacteroides acetoethylicus, that is prevalent in volcanic features where organic matter is vigorously being decomposed is described. T. acetoethylicus is a nonsporing, obligately anaerobic rod that stains gram-negative and exists singly or in pairs. Electron micrographs revealed peritrichous flagellation and a distinctive outer wall envelope structure without an outer wall membrane layer. The temperature range for growth was >40°C and <80°C; the pH range was between 5.5 and 8.5. The DNA base composition was 31±1 mol% guanosine plus cytosine. Fermentable carbohydrates included glucose, mannose, cellobiose, lactose, maltose, sucrose and starch. Growth on glucose in complex medium was associated with a 30 min doubling time; and ethanol, acetate, H2/CO2, butyrate and isobutyrate accounted for a balanced fermentation. Lactic acid was not formed. Growth was inhibited by O2, 2% NaCl, penicillin, streptomycin, vankomycin and neomycin, but not by chloramphenicol or hydrogen (2 atm). Glucose was metabolized via the Embden-Meyerhoff Pathway. A molar growth yield of 18.3 g cell per mol glucose and an ATP yield of 8 g cell per mol ATP produced was obtained. These results support the absence of detectable cytochromes and suggest that energy conservation is via substrate level phosphorylation alone.

Key words

Thermobacteroides acetoethylicusSpecies descriptionMicrobial diversityCaldoactive anaerobeEthanol/acetate productionGlycolysisGrowth yields



deoxyribonucleic acid


adenosine triphosphate


low phosphate buffered basal


tryptone yeast extract glucose


optical density


molar ATP yield


guanosine plus cytosine

Copyright information

© Springer-Verlag 1981

Authors and Affiliations

  • Arie Ben-Bassat
    • 1
  • J. G. Zeikus
    • 1
  1. 1.Department of BacteriologyUniversity of WisconsinMadisonUSA