Geogenic factors as drivers of microbial community diversity in soils overlying polymetallic deposits

Abstract

This study shows that the geogenic factors landform, lithology and underlying mineral deposits (expressed by elevated metal concentrations in overlying soils) are key-drivers of microbial community diversity in naturally metal-rich Australian soils with different landuse, i.e., agriculture vs. natural bushland. 168 soil samples were obtained from two metal-rich provinces in Australia, i.e., the Fifield Au-Pt-field (New South Wales) and the Hillside Cu-Au-U-rare-earth-element (REE) deposit (South Australia). Soils were analyzed using three-domain multiplex terminal-restriction-fragment-length-polymorphism (M-TRFLP) and PhyloChip microarrays. Geogenic factors were determined using field-mapping techniques and analyses of >50 geochemical parameters. At Fifield, microbial communities differed significantly with geogenic factors and equally with landuse (P<0.05). At Hillside, communities in surface soil (0.03-0.2 m depth) differed significantly with landform and landuse (P<0.05). Communities in deeper soils (>0.2 m) differed significantly with lithology and the mineral deposit (P<0.05). Across both sites, elevated metal contents in soils overlying mineral deposits were selective for a range of bacterial taxa, most importantly Acidobacteria, Bacilli, and Beta- and Epsilon-Proteobacteria. In conclusion, long-term geogenic factors can be equally important in determining soil microbial community diversity than landuse.