Has cupper ion any effect on Sinorhizobium Melitoili bacteria?

Abstract

Sinorhizobium meliloti is a soil bacterium that in symbiosis with Alfalfa leguminous plants fixes N2 to ammonia. This process occurs after an intimate communication between host and microsimbiont in the rhizosphere niche. This soil bacterium may suffer biotic and abiotic stresses in this complex environment. Resistance to any of this stresses can be an advantage for this type of bacteria. In this work we test the effects of Cupper ion in the bacterium Sinorhizobium meliloti. We found an effect on pigmentation and this effect is specific of each isolate (i.e. it is very pronounced for the isolate AK83 from Aral sea in Russia). On the other hand, comparison of Cupper ion resistance phenotype between isolates 1021 and GR4 suggests that the resistance of GR4 could be due to a set of 10 genes found in the cryptic plasmid pRmeGR4a of this strain. However, this resistance phenotype also appears in other isolates, and it could be explained by an alternative phenotype as Exopolysaccaride production (EPS+).