Abstract
The increase of bacterial community tolerance to Cu, and of cotolerance to the antibiotics tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC), was studied in three soils spiked with six different Cu concentrations (resulting in 0, 125, 250, 500, 750 and 1000 mg kg−1 into soils) in a laboratory experiment, after 42 days of incubation. The results show significant increases of bacterial community tolerance to the metal when soil Cu concentrations were between 125 and 500 mg kg−1. Moreover, Cu soil pollution also caused cotolerance to the three antibiotics studied but for higher Cu concentrations (1000 mg kg−1).
Highlights
Soil pollution due to Cu is widely extended worldwide, mainly caused by human activities such as agriculture, mining or industry
The results obtained in this study show that Cu pollution may cause increases in bacterial community tolerance to the antibiotics TC, OTC and CTC (Figure 1; Figure 3)
The addition of Cu to the soils studied caused a significant increase in bacterial community expected result, previously found by other authors [5,13,33,39,40,41]
Summary
Soil pollution due to Cu is widely extended worldwide, mainly caused by human activities such as agriculture, mining or industry. Especially regarding allowable threshold for Cu concentrations, is the increase of bacterial community tolerance to antibiotics in Cu polluted soils. It is well known that the increase of the concentration of any pollutant in a soil may suppose a selection pressure on soil bacterial communities, causing tolerance to that pollutant [7]. This effect is called pollution-induced community tolerance (PICT) and may be useful to quantify the harmful effects produced by pollutants on soil bacteria. Cu pollution may increase the bacterial community tolerance to other pollutants, such as different heavy metals or antibiotics [5,12,13]
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