Name: "Bacteroides fragilis subsp. thetaiotaomicron" (Distaso 1912) Holdeman and Moore 1970

Category: Subspecies

Proposed as: comb. nov.

Basonym: "Bacillus thetaiotaomicron" Distaso 1912

Etymology: the.ta.io.ta.o.mi’cron. N.L. neut. n. iotaomicron; N.L. neut. n. thetaiotaomicron, a combination of the Greek letters theta, iota and omicron, relating to the morphology of vacuolated forms (nominative in apposition)

Pronunciation (Latin), gender: … t^he-ta-io-ta-o-MI-kron, masculine

Nomenclatural type: ATCC 29148; CCUG 10774; CIP 104206; DSM 2079; JCM 5827; NCTC 10582; VPI 5482

See detailed strain information at

Conduct genome-based taxonomy at

16S rRNA gene: M58763 Analyse FASTA

Original publication: Holdeman LV, Moore WEC. Bacteroides. In: Cato EP, Cummins CS, Holdeman LV, Johnson JL, Moore WEC, Smibert RM, Smith LD (eds), Outline of clinical methods in anaerobic bacteriology, Virginia Polytechnic Institute Anaerobe Laboratory, Blacksburg, 1970, p. 1-107.

Nomenclatural status: not validly published

Taxonomic status: synonym (and no standing)

Correct name: Bacteroides thetaiotaomicron (Distaso 1912) Castellani and Chalmers 1919 (Approved Lists 1980)

Risk group: 2

• Synonyms:

  • Name	Kind
    "Bacillus thetaiotaomicron" Distaso 1912	homotypic synonym, not validly published, basonym of name in Approved Lists, distinct rank
    Bacteroides thetaiotaomicron (Distaso 1912) Castellani and Chalmers 1919 (Approved Lists 1980)	homotypic synonym, validly published under the ICNP, distinct rank

• Notes:
  • 😷 The risk group for Belgium has been imported on 2024-02-05. The full classification is: risk group = 2, note = "human pathogen". — The risk group for Canada has been imported on 2024-02-27. The full classification is: risk group = 2, note = "Animal classification RG: 1 - Security sensitive biological agent: No - Terrestrial animal pathogen under Canadian Food Inspection Agency authority: No - Containment level: Containment Level 2". — 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.

Parent taxon: Bacteroides fragilis (Veillon and Zuber 1898) Castellani and Chalmers 1919 (Approved Lists 1980)

Assigned by: Holdeman LV, Moore WEC. Bacteroides. In: Cato EP, Cummins CS, Holdeman LV, Johnson JL, Moore WEC, Smibert RM, Smith LD (eds), Outline of clinical methods in anaerobic bacteriology, Virginia Polytechnic Institute Anaerobe Laboratory, Blacksburg, 1970, p. 1-107.

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Record number: 4698