Methanobacterium thermoautotrophicum has been reported to require nickel for growth and to contain high concentrations of a nickel tetrapyrrole designated factor F4o. In this communication it is shown that all methanogenic bacteria investigated incorporated nickel during growth and also synthesized factor F43o. This was also true for Methanobrevibacter smithii, which is dependent on acetate as a carbon source, and for Methanosarcina barkeri growing on acetate or methanol as energy sources. Other bacteria, including Acetobacterium woodii and Clostridium thermoaceticum, contained no factor F430. It is further shown that two yellow nickel-containing degradation products were formed from factor F43o when heated at pH 7. This finding explains why several forms of factor F43o were found in methanogenic bacteria when a heat step was employed in the purification procedure. Growth of Methanobacterium thermoautotrophicum has been shown to be dependent on nickel (23). The transition metal was found to be a component of factor F4o (7, 9, 27), a yellow compound present in M. thermoautotrophicum (17). Ellefson and Wolfe (W. L. Ellefson and R. S. Wolfe, J. Biol. Chem., in press) recently obtained evidence that factor F4w may be the prosthetic group of methyl coenzyme M (CoM) reductase. The complete structure of factor F4o has not yet been elucidated. Labeling studies with ['4C]succinate and [8-'4C]aminolevulinic acid indicate that factor F4w has a nickel tetrapyrrole structure (5, 6). The only other organism in which factor F430 has been found is Methanobacterium bryantii (27), a member of the same genus as M. thermoautotrophicum (1). Two nickel-containing yellow compounds were isolated from this methanogen which were designated factors F4wa and-b. Whether less related methanogenic bacteria also contain nickel tetrapyrroles similar to or identical with factor F4wa orb has not yet been investigated. In the following communication, it is shown that all methanogens examined contained factor F4o: Methanobrevibacter smithii, Methanococcus vannielii, Methanospirillum hungatii, and Methanosarcina barkeri. From these organisms, two are of special interest: (i) M. smithii, because it lacks the ability to grow autotrophically, and (ii) M. barkeri, because this methanogen can grow organotrophically on acetate, methanol, or methyl amines. All other methan-ogens grow on H2 plus C02 or fornate as the sole energy source (1, 18, 28). MATERIALS AND METHODS The 80% H2-20% C02 gas mixture (H2 > 99.993%; CO2 > 99.995%) and H2S (>99.0%) were from Messer Griesheim (Diisseldorf). QAE-Sephadex A-25 was from Pharmnacia Fine Chemicals (Uppsala); Bio-Gel P-6 (100-200 mesh) was from Bio4Rad Laboratories (Munchen). Thin-layer cellulose plates or silica gel plates were from E. Merck (Dannstadt). ['NiJnickel II chloride (11.8 mCi/mg of nickel) was from Amersham Buchler (Braunschweig), and Aqualuma scintillator was from Baker Chemicals (Deventer). Pyridine-2-carbaldehyde-2-chinolyl-hydrazone (purum) was from Fluka (Buchs). Acetobacterium woodii strain WB1 (DS...

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We performed hybridizations between labeled rRNAs from seven representative members of the family Pasteurellaceae and from three other taxa on the one hand and DNAs from 53 strains known or presumed to belong to the Pasteurellaceae on the other hand. The members of the Pasteurellaceae are most closely related to members of the Enterobacteriaceae, the Vibrionaceae, the Aeromonadaceae, and the genus Alteromonas

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In the course of post-mortem bacteriological examinations, several previously unreported bacterial strains were isolated from budgerigars, pigeons, kestrels, and a goose. They have been separated into three distinct collectives according to their cultural, morphological, and biochemical characteristics. Since they require V factors, they were tentatively assigned to the genus Haemophilus Winslow et al. 1917. This preliminary classification was checked by determination of guanine + cytosine contents and genome sizes and by DNA:DNA hybridization tests among reference strains of the three new avian taxa and recognized species of the family Pasteurellaceae Pohl 1981. With the same methods, the genetic relationships of Haemophilus paragallinarum Biberstein and White 1969 within the family were determined. It could be shown that the three avian Haemophilus-like taxa have to be regarded as new species within the family Pasteurellaceae not affiliated with the recognized genera Actinobacillus, Haemophilus and Pasteurella. H. paragallinarum must be excluded from the genus Haemophilus because of its closer relationship to the actinobacilli. All strains investigated can be differentiated from each other and from recognized species of Pasteurellaceae using an appropriate set of biochemical tests.