Involvement of a Selenoprotein in Glycine, Sarcosine, and Betaine Reduction by Eubacterium acidaminophilum

Abstract

Eubacterium acidaminophilum is a versatile anaerobic bacterium fermenting amino acids and related compounds (Zindel et al. 1988). Glycine degradation to NH₃, CO₂, and acetate requires the presence of 1 µM selenite (optimum) as does the reduction of betaine, sarcosine, or creatine to acetate, methylamines and urea (Fig. 1) irrespective of NAD(P)H, H₂, formate, or e.g., valine being the reductant. However, growth on serine is independent of selenite addition as that on alanine, aspartate, valine, leucine, and malate in the presence of an H₂-scavenging organism. The involvement of selenium in glycine metabolism is well documented for a variety of anaerobic bacteria such as Clostridium sticklandii, C. lentoputrescens (Turner and Stadtman 1973; Stadtman 1978), C. sporogenes (Costilow 1977), the purinolytic species C. purinolyticum, C. acidiurici, and C. cylindrosporum (Dürre and Andreesen 1982, 1983), Peptostreptococcus magnus, P. glycinophilus (Dürre et al. 1983), and C. histolyticum (Lebertz and Andreesen 1988). Betaine reduction has so far only been studied with C. sporogenes (Naumann et al. 1983). The observed formation of trimethylamine was dependent on the presence of 1 µM selenite.

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