Analysis of the interaction of antibiotics and organic matter in natural water: spectral studies
Paramonova A.1,2, Terekhova V.1,2, Patsaeva S.3
1.Faculty of Soil Sciences, M.V.Lomonosov Moscow State University, Moscow, Russia;
2.A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia;
3.Faculty of Physics, M.V.Lomonosov Moscow State University, Moscow, Russia.
Abstract
The widespread distribution of antibiotics in the environment and the increase in the pool of resistance genes in microbial communities raise concerns about the natural loss of the effectiveness of their targeted use. The behavior of antibiotics in natural environments, their interaction, in particular, with organic substances, has not been sufficiently studied for a number of reasons, including methodological ones.
We applied an optical method for measuring the absorption spectra of aqueous samples dissolved organic matter (DOM) in natural water with the addition of antibiotics (tetracycline and ampicillin) and lignohumate (an organic substance (humic preparation, highly soluble in water that dissolves well in water) in order to identify their possible interaction. Absorption spectra were registered in the range of 200-700 nm using a Solar PB2201 spectrophotometer for aqueous sample placed in quartz cells with a path length of 1 cm in order to identify their possible interaction.
As a result, the characteristics of the spectra were obtained, which indicate the presence of the analyzed substances in the composition of sea and fresh water. The absorption spectra of dissolved organic matter (DOM) of sea water - lignohumate and antibiotics - tetracycline and ampicillin were recorded. The absorption spectra of DOM in seawater showed monotonous decrease along with wavelength. When using preparations of lignohumate, absorption band with a maximum at 270 nm was observed (due to residues of phenolic structures), signaling its presence in sea and cultivation water. The optical density of DOM in seawater showed an inverse dependence on the change in wavelength (the shorter the wavelength, the higher the optical density).
When using humic substances, absorption bands with a maximum at 270 nm were observed, signaling its presence in sea and fresh water. When measuring samples with antibiotics, more pronounced absorption bands were found at 380 nm, which clearly made it possible to isolate and separate samples with ampicillin and tetracycline.
The absorption bands of the antibiotic tetracycline practically do not change in both sea and fresh water (except for a slight change in the sample with tetracycline at a wavelength of 290-310 nm, which was presumably due to the degradation of tetracycline under the influence of light). The stable state of the absorption spectrum of sea and fresh water is also confirmed by the results of measurements of samples with ampicillin. This suggests that there is no interaction between organic matter of natural water and the antibiotic. At the same time, the presence of intrinsic absorption bands of antibiotics allows quantitative measurements of the concentration of antibiotics in water.
This work was partly supported by Moscow State University Grant for Leading Scientific Schools «Depository of the Living Systems» in a frame of the MSU Development Program and carried out within the framework of the RFBR project №18-44-920007 «Role of global and local factors for the formation of ichthyoplanctonic communities in the Black Sea»
Speaker
Anastasia Paramonova
Lomonosov Moscow State University
Russia
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