Copper and temperature modify microbial communities, ammonium and sulfate release in soil

10 páginas.-- 4 figuras.-- 3 tablas.-- 26 referenciasRecent studies suggest an important role of thermophilic bacterial communities of the Phylum Firmicutes on soil C, N and S cycling, and a positive effect on crop productivity through the production of sulfate (SO2 4) and ammonium (NHþ4), essential plant nutrients. Copper (Cu) is commonly supplemented to soils as a fungicide in phytosanitary treatments although its consequences to the bacterial communities is frequently overlooked. Herein, we report on the influence of temperature and Cu on the microbial communities, namely those of the Phylum Firmicutes, from a soil collected at an olive orchard in S Portugal. Community fingerprints and band identification through sequencing was combined with measurement of SO2 4 and NHþ4 production at different supplemented amounts of Cu and at moderate and high temperatures (30 C and 50 C, respectively). Both temperature and Cu induced changes in these communities, selecting for specific bacteria. Temperature induced the dominance of Brevibacillus, and Cu addition to soil caused a reduction of SO2 4 release by soil bacteria. Ammonium production during bacterial growth at moderate and high temperatures was not affected by Cu addition. A Cu-tolerant thermophilic isolate, belonging to the Bacillus genus, showed significant inhibition by high Cu concentrations and a reduction of NHþ4 release during growth; genera Brevibacillus and Bacillus have been previously reported as high NHþ4 and SO2 4 producers of the Firmicutes phylum. Results indicate that Cu treatments select specific tolerant bacterial strains which could influence natural soil fertilization in Cu-treated orchards.This work was funded by FEDER Funds through the Operational Program for Competitiveness Factors (COMPETE) and National Funds through FCT (Foundation for Science and Technology) under the Strategic Project PEst-C/AGR/ UI0115/2011. We thank Eng. G. Pinheiro from Eugenio Almeida Foundation (FEA) for providing access to an FEA olive orchard and Professor C. Alexandre for guidance in soil parameters evaluation.Peer reviewe