Control of the expression of bacterial genes involved in symbiotic nitrogen fixation

Complete genome sequence of the Robinia pseudoacacia L. symbiont Mesorhizobium amorphae CCNWGS0123

Mesorhizobium amorphae CCNWGS0123 was isolated in 2006, from effective nodules of Robinia pseudoacacia L. grown in lead-zinc mine tailing site, in Gansu Province, China. M. amorphae CCNWGS0123 is an aerobic, Gram-negative, non-spore-forming rod strain. This paper characterized M. amorphae CCNWGS0123 and presents its complete genome sequence information and genome annotation. The 7,374,589 bp long genome which encodes 7136 protein-coding genes and 63 RNA coding genes, contains one chromosome and four plasmids. Moreover, a chromosome with no gaps was assembled.

Low pH changes the profile of nodulation factors produced by Rhizobium tropici CIAT899

Rhizobium tropici CIAT899 has been cataloged as a nodulator of bean, a plant often growing in areas characterized by highly acidic soils. The purpose of this work was to explore the effects of acidity on the production of Nod factors by this strain and their impact on the establishment of effective symbioses. We report that acidity increases rhizobial Nod factors production, and we exhaustively study the nodulation factor structures produced under abiotic stress. Significant differences were observed between the structures produced at acid and neutral pH: 52 different molecules were produced at acid pH, 29 at neutral pH, and only 15 are common to bacteria grown at pH 7.0 or 4.5. The results indicate that R. tropici CIAT899 has successfully adapted to life in acidic soils and is a good inoculant for the bean under these conditions.