Genomics for the environment: the hidden power of bacteria

Plants harbor a plethora of microorganisms with which they mutually interact, so to be considered as ‘super-organisms’. Plants are able to shape their associated microbiome and to recruit microbes useful for nutrition, growth and defense from pathogens and adverse environmental conditions. The genomics of plant associated microorganisms is then an emerging field with highly important outcomes for agriculture and, in general, for green biotechnologies. In the last years, an increasing number of genomes from plant-associated microorganisms have been sequenced, discovering an extraordinary number of genes potentially useful for biotechnology applications. This presentation will review some of the relevant application of plant associated bacterial genomics and will focus on the exploration of the genome of the plant symbiont Sinorhizobium meliloti for genes relevant for the adaptation to heavy metal polluted soil. Heavy-metal tolerance in bacteria is indeed a widespread phenotype; in particular nickel tolerance has been characterized as depending on the nre system, which employs a Ni/H+ antiporter (NreB) to pump nickel out from the cell. An orthologous of nreB gene was found in Sinorhizobium meliloti by genome scanning. The evolutionary origin of this gene and its functions have been extensively studied and a perspective for its potential biotechnology applications will be reviewed.