Description of a New Strain of Methanothrix soehngenii and Rejection of Methanothrix concilii as a Synonym of Methanothrix soehngenii

Abstract

A new mesophilic strain of Methanothrix, strain FE, was highly purified from the sludge of an anaerobic digester after enrichment on sodium acetate and is described. Strain FE was compared with other strains of Methanothrix, Methanothrix soehngenii strain OpfikonT (= DSM 2139T) (T = type strain) and Methanothrix concilii strain GP6T (= DSM 3671T). The differences within the strains were mainly related to their requirement for yeast extract. The three strains were found to be similar in their deoxyribonucleic acid guanine-plus-cytosine contents (50.2 to 52.6 mol %) and showed 100 % deoxyribonucleic acid-deoxyribonucleic acid homology. For these reasons we propose to recognize synonymy, reject the name Methanothrix concilii Patel 1985, 35223, and assign this organism to the species Methanothrix soehngenii Huser, Wuhrmann and Zehnder 1983, 33: 439.Methanothrix soehngenii was first isolated by serial dilution from a continuous culture on acetate starting from anaerobically digested sludge in Switzerland (17, 40; B. A.Huser, thesis, Eidgenossischen Teschnischen Hochschule, Zurich, Switzerland, 1981). This bacterium was unique at that time among the methane bacteria because of its ability tlo split acetate into methane and carbon dioxide and its inability to use other methanogenic substrates, especially H,-C02. It was first described as a slow-growing bacterium with doubling times ranging from 5 to 8 days. This bacterium was positioned in the family Methanosarcinaceae by 16s ribosomal ribonucleic acid oligonucleotide sequencing (33). In 1984 (27), Patel described the isolation of Methanothrix concilii, which differed from Methanothrix soehngenii mainly by deoxyribonucleic acid (DNA) base composition and nutritional requirements. In this paper we characterize a new strain of Methanothrix, strain FE, and compare it with the two mesophilic type strains of the genus. MATERIALS AND METHODSSources of strains. Strain FE was initially purified from the sludge of an industrial mesophilic anaerobic contact digester treating wastewaters from the vegetable-canning industry (39). Methanothrix soehngenii strain OpfikonT (= DSM 2139T) (T = type strain) and Methanothrix concilii strain CiP6T (= DSM 3671T) were obtained from the Deutsche Slammlung von Mikroorganismen, Gottingen, West Germany. All of the strains used for immunological studies were also obtained from the Deutsche Sammlung von Mikroorganismen, except for Methanosarcina sp. strains CHTI55, MST-A1, and MC3, which were isolated in our laboratory, and Methanobrevibacter arboriphilicus AZ and Methanosarcina barkeri MST, which were gifts from J. G. Zeikus.Media and culture conditions. Cultivation of methanogens was done on BCYT medium as previously described (37). The medium was buffered with 50 mM HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) or PIPES [piperazine-l,4-bis(2-ethanesulfonic acid)] unless otherwise indicated. The anaerobic gas was an N,-CO, mixture (85:15). * Corresponding author.The sterile media were inoculated with 2% (vol/vol) portions of previo...

Methanosaeta concilii gen. nov., sp. nov. ("Methanothrix concilii") and Methanosaeta thermoacetophila nom. rev., comb. nov.

“…based on blackening of Postgate medium) and a rodshaped sporeformer (H. Hippe, DSM, personal communication). The presence of contaminating bacteria in strains OpfikonT and FE of Methanothrix soehngenii was confirmed in our laboratory and by Touzel et al (23). No axenic culture of either strain OpfikonT (= DSM 2139T) or FE (= DSM 3013) has been deposited with the DSM (Hippe, personal communication).…”

Challenging Opinion 75

“…In studies on the type strains of the species Methanothrix soehngenii and Methanothrix thermoacetophila, Touzel et al (1988), Patel & Sprott (1990), Stackebrandt et al (1982) and Kamagata et al (1992) used either one or both of the type strains in their studies of protein patterns, DNA-DNA hybridization, G+C content and 16S rRNA gene sequencing, without addressing the question of whether the filament-forming methanogen described by the original authors could be 'critically identified'; in other words, they accepted the fact that they were dealing with data obtained from the methanogen. Patel & Sprott (1990), however, called into question the purity of strain Opfikon (the type of Methanothrix soehngenii) in order to create the new genus Methanosaeta, with Methanosaeta concilii as the type species.…”

“…As long as Methanothrix soehngenii and Methanothrix concilii were treated as different species, Patel (1984) did not call into question the published data collected on Methanothrix soehngenii. It should also be noted that, although Touzel et al (1988) indicated that Methanothrix soehngenii and Methanothrix concilii should be treated as synonyms, their proposal that the name Methanothrix concilii be rejected has no standing in nomenclature. Kamagata et al (1992) have also indicated that the name Methanothrix thermoacetophila should be rejected because the type was originally not based on a pure culture.…”

Isolation and Characterization of a Novel Thermophilic Methanosaeta Strain

“…was first described as an "acetate organism" by Zehnder et al, and these authors designated their organism Methanothrix soehngenii Opfikon (11,28). After this description, several other mesophilic Methanosaeta strains were isolated (8, 19,26). Very recently, Patel and Sprott, who purified Methanothrix concilii GP6 (19), proposed that the genus Methanothrix should be changed to the genus Methanosaeta because the genus Methanothrix is nomenclaturally invalid according to the International Code of Nomenclature of Bacteria (13,20).…”

“…Very recently, Patel and Sprott, who purified Methanothrix concilii GP6 (19), proposed that the genus Methanothrix should be changed to the genus Methanosaeta because the genus Methanothrix is nomenclaturally invalid according to the International Code of Nomenclature of Bacteria (13,20). On the basis of the proposal by Patel and Sprott (20) and Touzel et al (26), the mesophilic strains previously described (11,12,19,26) should be assigned to the species Methanosaeta concilii.…”