Enzymes of arginine biosynthesis in methanogenic bacteria

Summary Methanobacterium thermoautotrophicum, Methanococcus vannielii andMethanobrevibacter arboriphilus, the 3 methanogenic bacteria tested, possessed an ornithine acetyltransferase and an arginine-sensitiveN-acetylglutamate 5-phopshtransferase. These 2 enzymes, as well as acetylornithinase and ornithine carbamoyltransferase, were insensitive to oxygen and were present at activity levels comparable to the levels observed in eubacteria.Acknowledgments. This work was supported by the Swiss National Foundation for Scientific Research (project No. 3.287.82). We thank A. Kiener for valuable discussions.