Geomicrobiology of extreme soils along a transect-slope
Résumé
One third of New Caledonia is constituted of ultramafic rocks. The soils originating from these rocks are considered extreme since they are characterized by low organic matter and high heavy metal content among which nickel is the most abundant. The open cut mines for nickel extraction have a significant impact on the environment by releasing even higher concentration of heavy metals. A new mine, located on the Koniambo, north of New Caledonia,is about to be exploited. This is a unique occasion to study the impact of anthropogenic activity on the microbial diversity. Furthermore this work aims to understand the relations between the soils characteristics and the structure of the microbial communities. We used a DNA microarray, which is an innovative metagenomic tool, to assess the microbial biodiversity after we designed specific 16S oligonucleotides. We showed that the microbial community structures vary strongly in response to local characteristics such as the edaphic parameters and/or the vegetation. For example actinomycetes were dominant in high-nickel concentration soils and planctomycetes were associated with gravelly soils. This work emphasizes the effects of the environment on the microbial biodiversity and the dynamic underlying structure. Our improved knowledge will also help in the rehabilitation of the Koniambo site after the mining exploitation.