Figure 1 shows the phylogenetic neighborhood of T. acidaminovorans strain Su883^T in a 16S rRNA based tree. The three 16S rRNA gene sequences in the genome of strain Su883^T differed from each other by up to three nucleotides, and by up to 29 nucleotides (2%) from the previously published 16S rRNA sequence, generated from DSM 6589 (AF071414). The significant difference between the genome data and the reported 16S rRNA gene sequence, which contains ten ambiguous base calls, is most likely due to sequencing errors in the previously reported sequence data.

T. acidaminovorans cells are curved rods of 0.5-0.6 × 2.5-3.0 µm in size (Table 1 and Figure 2), with round ends, occur singly, in pairs, or in long chains when grown in a complex medium [3]. The organism is Gram-negative, non-spore-forming, moderately thermophilic, motile by means of a tuft of lateral flagella at the concave side, and strictly anaerobic for growth [1]. Interestingly, it tolerates flushing with air for at least one hour, and it produces catalase [3]. While being exposed to air, strain Su883^T loses its motility [3]. Strain Su883^T is able to grow by oxidative decarboxylation of succinate to propionate. A mechanism for reductive propionate formation could be excluded [3]. Glutamate, α-ketoglutarate, histidine, arginine, ornithine, lysine, and threonine are fermented to acetate and propionate. Serine, pyruvate, alanine, glucose, fructose, xylose, glycerol and citrate are fermented to acetate. Branched-chain amino acids are converted to branched-chain fatty acids. Hydrogen is the only reduced end product [3]. The growth and the substrate conversion are strongly enhanced by co-cultivation with methanogens, e.g., M. thermoautotrophicum [3]. Strain Su883^T contains b-type cytochromes [3]. Originally, it was reported that in strain Su883^T thiosulfate, nitrite, sulfur and fumarate are not reduced [3]. However, a more recent study shows that, although elemental sulfur (1%) inhibits the growth of strain Su883^T on glucose, strain Su883^T could grow lithoheterotrophically with H₂ as electron donor, S⁰ as electron acceptor, and yeast extract as carbon source [16]. The catablolism of arginine has been studied in detail. Apparently, degradation of arginine occurs by the arginine deiminase (ADI) pathway [2]. No activity of arginase, a key enzyme of the arginase pathway, could be detected [2]. No growth was observed on glycine, aspartate, gelatin, xylose, ribose, galactose, lactose, sucrose, mannose, lactate, ethanol, methanol, acetoin, betaine, malonate, and oxalate [3]. With either succinate, α-ketoglutarate or glutamate, the following enzyme activities were measured in cell free extracts: propionyl CoA:succinate IISCoA transferase, propionate kinase, acetate kinase, glutamate dehydrogenase, pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, malate dehydrogenase, citrate lyase and hydrogenase [3]. The following enzymes were not detected: succinate thiokinase, fumarate reductase, succinate dehydrogenase, β-methylaspartase, hydroxyglutarate dehydrogenase, isocitrate dehydrogenase and formate dehydrogenase [3]. Unfortunately, no chemotaxonomic data are currently available for T. acidaminovorans strain Su883^T.