Characterisation of the mineralosphere bacterial communities and genes involved in the mineral weathering process in forest soils. – BACTOWEATHER

Unlike farmland, forests growing on acidic soils are among the terrestrial ecosystems that are least influenced or amended by man. Forests developed on acidic soils are characterized by an important stock of inorganic nutrients entrapped in poorly weatherable soil minerals. Aside from the contribution of rainwater, atmospheric deposits and the recycling of elements contained in falling leaves and dead roots, soil minerals (primary and secondary) constitute the main source of inorganic nutrients for the long-lasting functioning of forest ecosystems. The mineral weathering process is so of great importance because such minerals are not easily accessible to tree roots. To date, several bacterial genera have been noted for their ability to weather minerals and for some of them to improve tree nutrition. Nevertheless, few studies have focused their analyses on the mineral weathering bacterial communities in relation to their ecological origin, and the mechanisms used by bacteria to weather minerals as well as the genes involved remain poorly investigated or unknown. The proposed project will investigate the functional, metabolic and taxonomic characteristics of the bacterial communities colonizing a specific ecological niche of the soil, the mineralosphere, using cultivation dependent and independent approaches. The project will also decipher the genomic characteristics and the genes involved in mineral weathering in two model bacterial strains efficient to weather minerals and belonging to the genera Burkholderia and Collimonas, by combining sequencing, genomics, genetics and bioinformatics. At least, the impact of the minerals on the activity of the bacterial communities will be investigated. The identification of the mineral weathering bacterial communities as well as the understanding of the mechanisms used by bacteria to weather minerals are challenging era of research, not only for the fundamental and ecological significance of the mineral weathering process, but also because the bacteria or genes involved in this process may be used as bioindicators of the fertility status of a soil.