Name: Methanobacterium thermoflexum Kotelnikova et al. 1994

Category: Species

Proposed as: sp. nov.

Etymology: ther.mo.fle’xum. Gr. fem. adj. thermê, heat; L. neut. perf. part. flexum, curved, bent, crooked; N.L. neut. part. adj. thermoflexum, heat-(loving) and bent or crooked

Pronunciation (Latin), gender: … t^her-mo-FLE-ksum, neuter

Type strain: ATCC 51444; DSM 7268; IDZ; OCM 571; VKM B-1963

See detailed strain information at

16S rRNA gene: X99047 Analyse FASTA

Effective publication: Kotelnikova SV, Obraztsova AY, Gongadze GM, Laurinavichius KS. Methanobacterium thermoflexum sp. nov. and Methanobacterium defluvii sp. nov., thermophilic rodshaped methanogens isolated from anaerobic digester sludge. Syst. Appl. Microbiol. 1993; 16:427-435.

IJSEM list: Anonymous. Validation list no. 48. Validation of publication of new names and new combinations previously effectively published outside the IJSB. Int J Syst Bacteriol 1994; 44:182-183.

Nomenclatural status: validly published under the ICNP

Taxonomic status: synonym

Correct name: Methanothermobacter thermoflexus (Kotelnikova et al. 1994) Boone 2002

Risk group: 1

• Synonyms:

  • Name	Kind
    Methanothermobacter thermoflexus (Kotelnikova et al. 1994) Boone 2002	homotypic synonym, validly published under the ICNP
    "Methanothermobacter thermoflexus" (Kotelnikova et al. 1994) Wasserfallen et al. 2000	homotypic synonym, not validly published

• Notes:
  • ❗ Methanobacterium thermoflexum is the correct name instead if this species is regarded as a separate species (i.e., if its nomenclatural type is not assigned to another species whose name is validly published, legitimate and not rejected and has priority) within a separate genus Methanobacterium.
  • 😷 The risk group for Canada has been imported on 2024-02-27. The full classification is: risk group = 1, note = "Security sensitive biological agent: No - Terrestrial animal pathogen under Canadian Food Inspection Agency authority: No". — The risk group for Swiss Confederation has been imported on 2024-02-01. The full classification is: risk group = 1. — The risk group for Germany has been imported on 2023-10-29. The full classification is: risk group = 1. — If in doubt, use the risk group given in the regulations for your country and, if these are not available, use the risk group given in the catalogue of the culture collection from which you have obtained or intend to obtain the strain.
  • 🎓 Name mentioned 0 times in PubMed until 2025-06-04.
  • 🧍 However, this new combination was not described according to the Rules of the Bacteriological Code (1990 Revision), and it was not cited in the Notification List published in the March 2000 issue of the IJSEM [2]. Publication: Anonymous. Notification list. Notification that new names and new combinations have appeared in volume 50, part 1 of the IJSEM. Int J Syst Evol Microbiol 2000; 50:425-426.
  • 🧍 In the January 2000 issue of the International Journal of Systematic and Evolutionary Microbiology, Wasserfallen et al. [1] proposed to transfer Methanobacterium thermoflexum Kotelnikova et al. 1994 into the new genus Methanothermobacter as "Methanothermobacter thermoflexus" (Kotelnikova et al. 1994) Wasserfallen et al. 2000, comb. nov. However, this new combination was not described according to the Rules of the Bacteriological Code (1990 Revision), and it was not cited in the Notification List published in the March 2000 issue of the IJSEM [2]. Later, Methanothermobacter thermoflexus was listed in the second edition of the Bergey's Manual of Systematic Bacteriology [3] and it was validly published in Validation List no. 85 (Cf. infra) [4]. Publication: Wasserfallen A, Nolling J, Pfister P, Reeve J, Conway de Macario E. Phylogenetic analysis of 18 thermophilic Methanobacterium isolates supports the proposals to create a new genus, Methanothermobacter gen. nov., and to reclassify several isolates in three species, Methanothermobacter thermautotrophicus comb. nov., Methanothermobacter wolfeii comb. nov., and Methanothermobacter marburgensis sp. nov. Int J Syst Evol Microbiol 2000; 50:43-53. 🇨🇭
  • 🧍 Later, Methanothermobacter thermoflexus was listed in the second edition of the Bergey's Manual of Systematic Bacteriology [3] and it was validly published in Validation List no. 85 (Cf. infra) [4]. Publication: Boone DR. Genus IV. Methanothermobacter Wasserfallen, Nölling, Pfister, Reeve and Conway de Macario 2000, 51VP. In: Boone DR, Castenholz RW, Garrity GM (eds), Bergey's Manual of Systematic Bacteriology, second edition, vol. 1 (The Archaea and the deeply branching and phototrophic Bacteria), Springer-Verlag, New York, 2001, p. 230-233. 🇺🇸

Parent taxon: Methanobacterium Kluyver and van Niel 1936 (Approved Lists 1980)

Assigned by: Kotelnikova SV, Obraztsova AY, Gongadze GM, Laurinavichius KS. Methanobacterium thermoflexum sp. nov. and Methanobacterium defluvii sp. nov., thermophilic rodshaped methanogens isolated from anaerobic digester sludge. Syst. Appl. Microbiol. 1993; 16:427-435.

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Record number: 777810