The response of Rhizobium meliloti to L-methionine DL-sulphoximine.

A strain of Rhizobium meliloti has been shown to be capable of growth in the presence of methionine sulphoximine concentrations at least two orders of magnitude higher than that required for the complete inhibition of glutamine synthetase activity. Neither the specific growth rate, nor the nutritional requirements of the organism were affected by methionine sulphoximine in the medium. Rhizobium meliloti appeared to assimilate ammonia via the glutamate dehydrogenase pathway during growth in the presence of methionine sulphoximine. This suggests that Rhizobium meliloti may have some regulatory mechanism controlling ammonia assimilation that is not present in other enterobacteria possessing similar enzymatic machinery.