Assessing Bioactive Tetracycline in Soil Samples. Application of a German-Standard-Bioassay DIN 58940 Part 1–3 (5 pp)

Abstract

Background

Tetracycline (TC) is one of the most common antibiotics in animal husbandry. Concentrations of up to 200 µg TC kg–1 have been found in soils, which have repeatedly received pig manure, and it can be assumed that there is an accumulation in soil.

Methods

The established methods for chemical analysis of extractable TC in soil employ HPLC-UV or HPLC-MS-MS. These methods are quite expensive and require well-trained laboratory personnel and sophisticated high-technology equipment. For this reason, a German Standard Bioassay (DIN 58940 Part 1–3) was adjusted and validated in order to establish an alternative low-priced method for monitoring TC contents in soil samples. The tests were conducted with two soils (sand and loamy sand) spiked with TC at 6 concentrations. With this bioassay, TC in soils was analyzed and a simple quantification procedure was established. It will be demonstrated that sand and loamy sand soil properties have an influence on the recoveries of extractable, bioactive TC.

Results

In the loamy sand soil, less bioactive TC was extracted (15–25%) than in the sandy soil (30–55%), when tested against the aqueous TC-solution (100%) as a control. These results were confirmed by HPLC- MS-MS analyses. The bioassay was successfully employed in a degradation study in a greenhouse pot experiment.

Recommendation

It could prove to be expedient to use this bioassay in the assessment of other antibiotics as well.