Effect of Oxytetracycline and Chlortetracycline on Bacterial Community Growth in Agricultural Soils
Vanesa Santás-Miguel,
Manuel Arias-Estévez,
Montserrat Díaz-Raviña,
María José Fernández-Sanjurjo,
Esperanza Álvarez-Rodríguez,
Avelino Núñez-Delgado,
David Fernández-Calviño
Affiliations
Vanesa Santás-Miguel
Área de Edafoloxía e Química Agrícola, Departamento de Bioloxía Vexetal e Ciencia do Solo, Facultade de Ciencias, Universidade de Vigo, Campus As Lagoas, s/n 32004 Ourense, Spain
Manuel Arias-Estévez
Área de Edafoloxía e Química Agrícola, Departamento de Bioloxía Vexetal e Ciencia do Solo, Facultade de Ciencias, Universidade de Vigo, Campus As Lagoas, s/n 32004 Ourense, Spain
Montserrat Díaz-Raviña
Departamento de Bioquímica del Suelo, Instituto de Investigaciones Agrobiológicas de Galicia (IIAG-CSIC), Apartado 12, Avda Vigo s/n, 15780 Santiago de Compostela, Spain
María José Fernández-Sanjurjo
Departamento de Edafoloxía e Química Agrícola, Escola Politécnica Superior de Enxeñaría, Universidade de Santiago de Compostela, Campus Universitario, s/n 27002 Lugo, Spain
Esperanza Álvarez-Rodríguez
Departamento de Edafoloxía e Química Agrícola, Escola Politécnica Superior de Enxeñaría, Universidade de Santiago de Compostela, Campus Universitario, s/n 27002 Lugo, Spain
Avelino Núñez-Delgado
Departamento de Edafoloxía e Química Agrícola, Escola Politécnica Superior de Enxeñaría, Universidade de Santiago de Compostela, Campus Universitario, s/n 27002 Lugo, Spain
David Fernández-Calviño
Área de Edafoloxía e Química Agrícola, Departamento de Bioloxía Vexetal e Ciencia do Solo, Facultade de Ciencias, Universidade de Vigo, Campus As Lagoas, s/n 32004 Ourense, Spain
Toxicity on soil bacterial community growth caused by the antibiotics oxytetracycline (OTC) and chlortetracycline (CTC) was studied in 22 agricultural soils after 1, 8 and 42 incubation days. The leucine incorporation method was used with this aim, estimating the concentration of each antibiotic which caused an inhibition of 50% in bacterial community growth (log IC50). For OTC, the mean log IC50 was 2.70, 2.81, 2.84 for each of the three incubation times, while the values were 2.05, 2.22 and 2.47 for CTC, meaning that the magnitude of OTC toxicity was similar over time, whereas it decreased significantly for CTC with incubation time. In addition, results showed that the toxicity on bacterial community growth due to CTC is significantly higher than when due to OTC. Moreover, the toxicity on bacterial community growth due to both antibiotics is dependent on soil properties. Specifically, an increase in soil pH and silt content resulted in higher toxicity of both antibiotics, while increases in total organic carbon and clay contents caused decreases in OTC and CTC toxicities. The results also show that OTC toxicity can be well predicted by means of specific equations, using the values of pH measured in KCl and those of effective cation exchange capacity as input variables. CTC toxicity may be predicted (but with low precision) using pH measured in KCl and total organic carbon. These equations may help to predict the negative effects caused by OTC and CTC on soil bacteria using easily measurable soil parameters.
