Copper resistance in multispecies bacterial communities: a synthetic community study

Description

In the bacterial world, many different copper resistance were described (complexation, efflux, reduction, mineral formation, etc.). However, bacteria are never alone in ecosystems and usually live in complex bacterial communities such as biofilms composed of hundred of species. In these multispecies biofilms, interspecific interactions have probably a major ecological role. However, few elements are known about these interspecific interactions and their possible influence on the expression of metal resistance genes, particularly for copper. Are there bacterial strains able to resist high copper levels only in complex bacterial communities? How will different strains influence each other? What are the genes involved in cooperation? Are there cooperation genes in metal resistance clusters? To answer these questions a simplified ecosystem, composed of 4 bacterial strains, will be considered. For that, numerous bacterial strains will be isolated from a copper contaminated soil. These strains will the be grouped by 4 and placed in biofilm. Hundreds of combinations will be tested. The biofilms of 4 species that form the largest biomass in the presence of copper will be selected and studied further. The genome of the 4 strains will be determined. The proteome of the 4 isolated strains will then be compared to the proteome of the 4-species biofilm. Genes whose expression levels vary in the presence of the other strains will be studied further. These genes will then be eliminated from the corresponding strains (knockout mutants) and the mutant strains will be replaced in biofilm and studied. Genes potentially involved in the interspecific communication established during copper resistance will then be tentatively identified in the 4 species synthetic community.