Interactions between soil properties and tetracycline toxicity affecting to bacterial community growth in agricultural soil

The effect of tetracycline toxicity on the growth of soil bacterial communities was assessed using 22 agricultural soils with different pH values (between 4.1 and 7.4) and organic carbon concentrations (1.1–10.9%). Samples from all these soil types were spiked with different concentrations of tetracycline, and bacterial community growth was estimated after 1, 8, and 42 days of incubation, by using the H leucine incorporation method. Although tetracycline toxicity persisted in the soil during the incubation period, its magnitude gradually decreased with time. Moreover, tetracycline toxicity largely depends on soil characteristics, decreasing as a function of increasing organic matter, clay content, and effective exchangeable cation capacity (eCEC), and decreasing soil pH values. Further, an equation that allows the prediction of the direct effect of tetracycline on the growth of soil bacterial community was developed considering easily determinable parameters as the input; this equation will help achieve quick assessment of potentially hazardous situations.
This study has been funded by the Spanish Ministry of Economy and Competitiveness through the projects CGL2015-67333-C2-1-R and -2-R (FEDER Funds). David Fernández Calviño holds a Ramón y Cajal con- tract (RYC-2016-20411), financed by the Spanish Ministry of Economy, Industry and Competitiveness.