Cloning nitrogen fixing genes from Klebsiella pneumoniae in vitro and the isolation of NIF promoter mutants affecting glutamine synthetase regulation.

Abstract

The vast majority of terrestial nitrogen fixation occurs in the soil and in plants which possess prokaryotic nitrogen fixing symbionts (1). Industrial nitrogen fixation probably accounts for less than 10% of the total amount fixed, and the amount fixed by free-living soil bacteria is agronomically negligible (2). Unfortunately, nitrogen fixing symbiont plants do not include the world’s major cereal crops such as wheat, rice or corn; or grass, the world’s major forage crop. Thus, in technologically underdeveloped countries, agricultural productivity of the soil is frequently limited by the amount of nitrogen contributed to the soil by the growth of leguminous crops.