Ramping Up the Heat on Nitrogenase

摘要

On page 1783 of this issue, Mehta and Baross describe a hyperthermophilic methanogen that can fix nitrogen (N sub(2)). The authors isolated the organism from a deep ( similar to 1500 m) hydrothermal vent. Like other nitrogen-fixing bacteria and archaea, it uses the nitrogenase enzyme to tap the vast reservoir of dissolved N sub(2) gas for its nutritional needs for nitrogen. The discovery is noteworthy for several reasons: It establishes a new temperature maximum of 92 degree C for an active biological nitrogenase system, with biotechnological potential; it provides evidence for a new environment in which nitrogen fixation may occur; and it establishes yet another role for archaea in the marine nitrogen cycle. Furthermore, genomic analysis of this organism may provide important clues to the early evolution of the nitrogenase enzyme system.