Some problems with the genera Methanothrix and Methanosaeta
The type strain of ¤ Methanothrix soehngenii Huser et al. 1983 is contaminated by two morphologically distinct bacteria. According to the "old Rule 31a" (i.e. before January 2001), Methanothrix soehngenii is invalid. Consequently, the genus Methanothrix did not have nomenclatural standing.
Reference: PATEL (G.B.) and SPROTT (G.D.): Methanosaeta concilii gen. nov., sp. nov. ("Methanothrix concilii") and Methanosaeta thermoacetophila nom. rev., comb. nov. Int. J. Syst. Bacteriol., 1990, 40, 79-82.
Original article in IJSEM Online
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In a Request for an Opinion, Boone 1991 proposed that strain GP6 (= NRC 2989 = ATCC 35969= DSM 3671 = OCM 69), the type strain of Methanosaeta (Methanothrix) concilii, be adopted as the neotype of Methanothrix soehngenii. This would have the effect of reducing Methanosaeta (Methanothrix) concilii to a synonym, rendering it invalid. Patel 1992 has published a counterargument to this proposal. The Judicial Commission concluded that the interests of clarity and stability would be served best by denying the Request for an Opinion. Strain GP6 remains the type of Methanosaeta (Methanothrix) concilii; there does not appear to be an extant type strain for Methanothrix soehngenii, which remains a species of doubtful validity. Consequently, the genus Methanothrix remains a genus of doubtful validity.
References:
1 BOONE (D.R.): Strain GP6 is proposed as the neotype strain of Methanothrix soehngeniiVP pro synon. Methanothrix conciliiVP and Methanosaeta conciliiVP. Request for an Opinion. Int. J. Syst. Bacteriol., 1991, 41, 588-589.
Original article in IJSEM Online
2 PATEL (G.B.): A contrary view to the proposal to assign a neotype strain for Methanothrix soehngenii. Int. J. Syst. Bacteriol., 1992, 42, 324-326.
Original article in IJSEM Online
3 WAYNE (L.G.): Actions of the Judicial Commission of the International Committee on Systematic Bacteriology on Requests for Opinions published between January 1985 and July 1993. Int. J. Syst. Bacteriol., 1994, 44, 177-178.
Original article in IJSEM Online
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Boone and Kamagata 1998 [1], requested a Judicial Opinion to reject the name Methanothrix soehngenii as a nomen confusum and to place this name on the list of rejected names. This request was accepted by the Judicial Commission [2, 3]. However, this vote failed to take into consideration that the wording of Rule 31a had been changed in such a way that this Rule no longer makes references to mixed cultures [4, 5]. Moreover, the presence of more than one species in the culture of the strain Opfikon = DSM 2139 did not adversely affect the data collected [2].
References:
1 BOONE (D.R.) and KAMAGATA (Y.): Rejection of the species Methanothrix soehngeniiVP and the genus MethanothrixVP as nomina confusa, and transfer of Methanothrix thermophilaVP to the genus MethanosaetaVP as Methanosaeta thermophila comb. nov. Request for an Opinion. Int. J. Syst. Bacteriol., 1998, 48, 1079-1080.
Original article in IJSEM Online
2 DE VOS (P.), TRÜPER (H.G.) and TINDALL (B.J.): Judicial Commission of the International Committee on Systematics of Prokaryotes Xth International (IUMS) Congress of Bacteriology and Applied Microbiology. Minutes of the meetings, 28, 29 and 31 July and 1 August 2002, Paris, France. Int. J. Syst. Evol. Microbiol., 2005, 55, 525-532.
Original article by De Vos et al. 2005 in IJSEM Online
3 JUDICIAL COMMISSION OF THE INTERNATIONAL COMMITTEE ON SYSTEMATICS OF PROKARYOTES: Rejection of the genus name Methanothrix with the species Methanothrix soehngenii Huser et al. 1983 and transfer of Methanothrix thermophila Kamagata et al. 1992 to the genus Methanosaeta as Methanosaeta thermophila comb. nov. Opinion 75. Int. J. Syst. Evol. Microbiol., 2008, 58, 1753-1754.
Opinion 75 in IJSEM Online
4 DE VOS (P.) and TRÜPER (H.G.): Judicial Commission of the International Committee on Systematic Bacteriology. IXth International (IUMS) Congress of Bacteriology and Applied Microbiology. Minutes of the meetings, 14, 15 and 18 August 1999, Sydney, Australia. Int. J. Syst. Evol. Microbiol. 2000, 50, 2239-2244.
Original article by De Vos and Trüper 2000 in IJSEM Online
5 TINDALL (B.J.): Challenging Opinion 75. Int. J. Syst. Evol. Microbiol., 2008, 58, 1768-1771.
Original article in IJSEM Online
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Opinion 75 ruled to reject the genus name Methanothrix and the species name Methanothrix soehngenii Huser et al. 1983 on the grounds that the names contravene Rule 31a of the Code. In addition, the species Methanothrix thermophila was transferred to the genus Methanosaeta as Methanosaeta thermophila (Kamagata et al. 1992) Boone and Kamagata 1998 comb. nov. This opinion was challenged by B. J. Tindall for reasons of misinterpretation of the Code and contradictory assertions in the Opinion. So, B.J. Tindall requests that the Judicial Commission re-examines Opinion 75.
Reference: TINDALL (B.J.): Challenging Opinion 75. Int. J. Syst. Evol. Microbiol., 2008, 58, 1768-1771.
Original article in IJSEM Online
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On 6 August 2008, the Opinion 75 was reviewed by the Judicial Commission. The Minute 22 (2) of the meeting of the Judicial Commission, 3, 4 and 6 August 2008, Istanbul, Turkey, states the following:
(i) It was agreed unanimously that the name Methanothrix soehngenii Huser et al. 1983 does not contravene the wording of Rule 31a and is thus validly published.
(ii) It was agreed unanimously that the name Methanothrix thermoacetophila Nozhevnikova and Chudina 1988 does not contravene the wording of Rule 31a and is considered validly published.
(iii) It was agreed unanimously that the names Methanothrix thermophila Kamataga et al. 1992 and Methanothrix thermoacetophila Nozhevnikova and Chudina 1988 refer to the same taxon. The consequence of this ruling is that Methanothrix thermophila is illegitimate, should be rejected and Methanothrix thermoacetophila should be retained in its place.
(iv) It was agreed unanimously that the name Methanosaeta Patel and Sprott 1990 and Methanothrix Huser et al. 1983 refer to the same taxon.
As a consequence of these decisions, the name Methanosaeta is illegitimate and should be rejected as a source of confusion. It should be replaced with the genus name Methanothrix. The replacement name will be nom. nov. (sic) and all species in the genus Methanosaeta should be transferred to the genus Methanothrix.
Reference: GARRITY (G.M.), LABEDA (D.P.) and OREN (A.): Judicial Commission of the International Committee on Systematics of Prokaryotes. XIIth International (IUMS) Congress of Bacteriology and Applied Microbiology. Minutes of the meetings, 3, 4 and 6 August 2008, Istanbul, Turkey. Int. J. Syst. Evol. Microbiol., 2011, 61, 2775-2780.
Original article in IJSEM Online
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