Differential copper impact on density, diversity and resistance of adapted culturable bacterial populations according to soil organic status

作者：Lejon David P H; Pascault Noemie; Ranjard Lionel^*

来源：European Journal of Soil Biology, 2010, 46(2): 168-174.

DOI：10.1016/j.ejsobi.2009.12.002

• Bacteria
• Copper impact
• Soil organic matter
• Copper resistance

The effect of copper on the abundance, diversity and resistance of viable heterotrophic and copper resistant bacterial populations (Cu(R)) was evaluated in soils differing only by their amount and type of organic matter. These soils have been obtained using a vineyard soil that had been subjected to three different organic matter managements (Not Amended (NA) or amended with Straw (5) or Conifer Compost (CC)) in a long term field experiment. Soil microcosms were artificially contaminated with copper (250 mg Cu kg(-1) of soil) and incubated for 35 days. Throughout the incubation, a differential copper impact on viable heterotrophic and Cu(R) bacterial enumeration was demonstrated according to the soil organic status with a magnitude which followed the order: NA > CC >= S. Diversity of Cu(R) bacteria revealed no significant difference between the uncontaminated soils, as determined by 16S rRNA sequencing. However, copper spiking induced an enrichment of particular populations depending on soil, with Methylobacterium, Ralstonia and Staphylococcus like species becoming dominant in NA, S and CC soils, respectively. Evaluation of the copA gene distribution and diversity, through PCR detection and sequencing, revealed that few Cu(R) bacteria (from 7 to 13%) possessed this genetic determinant before the addition of metal. Copper contamination induced an increase in the dissemination of homologous copA genes only in Ralstonia like species indigenous to S soils. From a functional point of view, copper minimum inhibitory concentration for each Cu(R) strain was measured. It did not highlight variable copper resistance efficiency between strains belonging to different taxonomic groups, harboring or not the copA gene, and originating from different soils contaminated or not by copper.

• 出版日期2010-4