CHARACTERISTICS OF GLUTAMINE SYNTHETASE I AND II MUTANTS OF RHIZOBIUM

Abstract

Mutants of Rhizobium meliloti 41 and AK631 deficient in either glutamine synthetase I or II were characterized for growth and acetylene reduction activity. Comparison of the various mutants indicates that either GSI or GSII is competent to provide glutamine for cellular requirements with ammonia as the nitrogen source. The acetylene reduction activity of nodules induced by some GSI^- or GSII^- mutants was equal to the wild- type activity indicating that neither GS is required for symbiotic effectiveness and that either form is sufficient for effectiveness. No effect of purines on growth was found in the GS mutants of this strain.