Regulation of urease in Bradyrhizobium colonizing green gram (Vigna radiata (L.) Wilczek).

In the present study attempts have been made to characterize urease expression in slow growing Bradyrhizobium strains TAL442 and MO5 which are endosymbionts of green gram (Vigna radiata (L.)Wilczek). It was found that urease activity in vegetative cells of both the strains was inducible unlike their fast growing counterparts. Mode of regulation in TAL442 was governed by presence of ammonia. Urease expression was also detectable in bacteroids of both the strains which was not influenced by presence of external nickel chloride in high concentration, a situation detrimental to the vegetative cells.