"Heavy Metallophores"

Heavy metal accumulating plants can be employed to remediate contaminated soils. This cleanup approach termed phytoextraction is sustainable but relatively slow, because metal extraction is limited by the rate of metal uptake into shoots and by shoot biomass production. Bacteria associated with heavy metal accumulating plants have the potential to improve phytoextraction. They may improve plant performance, particularly under plant stress conditions, however, in addition they may greatly enhance heavy metal mobilization in soil making higher amounts of heavy metals available to the plant. In previous studies we identified bacteria belonging to the Microbacteriaceae having heavy metal mobilizing capacities, however, the mechanisms are unknown yet. Our hypothesis is that these bacteria are able to produce secondary metabolites, which are produced in the mobilization process. We will follow a genome sequence-based approach followed by chemical characterization to identify the genetic basis, chemical characteristics, distribution and expression patterns of the observed metallophores. In addition, their interaction with the plant host and relevance to phytoextraction will be analyzed in plant experiments with Salix smithiana.

Heavy metal accumulating plants can be employed to remediate contaminated soils. This cleanup approach termed phytoextraction is sustainable but relatively slow, because metal extraction is limited by the rate of metal uptake into shoots and by shoot biomass production. Bacteria associated with heavy metal accumulating plants have the potential to improve phytoextraction. They may improve plant performance, particularly under plant stress conditions, however, in addition they may greatly enhance heavy metal mobilization in soil making higher amounts of heavy metals available to the plant. We investigated bacteria belonging to the Microbacteriaceae having heavy metal mobilizing capacities, and aimed at elucidating the mechanisms involved. Our hypothesis was that these bacteria are able to produce secondary metabolites, which are involved in the mobilization process. We followed a genome sequence-based approach followed by chemical characterization to identify the genetic basis, chemical characteristics, distribution and expression patterns of the observed metallophores. The investigated strains, partly identified as novel species, were found to host several gene clusters encoding secondary metabolite genes, which were expressed under heavy metal conditions and a potential metal chelating compound was identified.