Degradation of streptomycin in aquatic environment: kinetics, pathway, and antibacterial activity analysis

Abstract

Streptomycin used in human and veterinary medicine is released into the environment mainly through excretions. As such, its elimination in water should be investigated to control pollution. In this study, the degradation of streptomycin in water was studied, and the influence of variables, including light exposure, solution pH, temperature, ionic strength, dissolved organic matter (DOM), and coexisting surfactants, on degradation was investigated. Streptomycin degradation was consistent with the first-order model in aquatic environments. Its degradation rate under light exposure was 2.6-fold faster than that in the dark. Streptomycin was stable under neutral conditions, but it was easily decomposed in acidic and basic environments. Streptomycin degradation was enhanced by high temperature, and its half-life decreased from 103.4 days at 15 °C to 30.9 days at 40 °C. This process was also accelerated by the presence of Ca and slightly improved by the addition of HA. Streptomycin degradation was suppressed by high levels of the cationic surfactant cetyltri- methylammonium bromide (CTAB), but was promoted by the anionic surfactant sodium dodecyl benzene sulfonate (SDBS). The main degradation intermediates/products were identified through liquid chromatography-mass spectrometry, and the possible degradation pathway was proposed. The antibacterial activity of streptomycin solution was also determined during degradation. Results showed that STR degradation generated intermediates/products with weaker antibacterial activity than the parent compound.

Effect of Sunlight on the Efficacy of Commercial Antibiotics Used in Agriculture

“…The half-life of streptomycin was determined to be nearly 105, 42, and 30 days at 15, 25, and 40 • C, respectively, implying a decreased rate of degradation when compared to oxytetracycline. A description of the possible degradation products of oxytetracycline and streptomycin are available (Xuan et al, 2010;Shen et al, 2017). Our results showing a faster loss of efficacy for oxytetracycline than streptomycin upon sunlight exposure are therefore in agreement with the reported degradation kinetics of these antibiotics.…”

“…Several reports on degradation kinetics and mechanisms of degradation of the antibiotics that are discussed here are available (Wang and Yates, 2008;Xuan et al, 2010;Slana and Dolenc, 2013;Liu et al, 2015;Shen et al, 2017;Leal et al, 2019a,b;Li et al, 2019b;Choi et al, 2020). It has been reported that the half-life of oxytetracycline at 25 • C is approximately 7 days, at 35 • C is 3 days and at 60 • C is 0.2 day, indicating a rapid temperaturedependent degradation of oxytetracycline, as the half-life at 4 • C is 120 days (Xuan et al, 2010).…”

“…According to the same study, the half-life due to photolysis in the presence of sunlight is in the same order of magnitude. A similar investigation exists evaluating the photostability and temperature stability of streptomycin (Shen et al, 2017). Briefly, the photodegradation of streptomycin is more modest than oxytetracycline by nearly 10-fold.…”

Dysbiosis and early mortality in zebrafish larvae exposed to subclinical concentrations of streptomycin

“…Even though streptomycin can degrade in the environment under the effect of light and temperature among other things, all three streptomycin concentrations used in this were previously reported in environmental surveys (Shen et al. 2017 ). Again, approximately 80% of media was exchanged daily for sterile 1 × E3 media with the relevant antibiotic concentration when applicable.…”

Bacteria From the Multi-Contaminated Tinto River Estuary (SW, Spain) Show High Multi-Resistance to Antibiotics and Point to Paenibacillus spp. as Antibiotic-Resistance-Dissemination Players

“…Some studies have shown that streptomycin can persist in aquatic environments for some time and its degradation products still maintain certain antibacterial activity (Shen et al, 2017). On the other hand, selection of Sm R bacteria in in vitro evolution experiments with low concentrations of antibiotic has been observed even after only 96 h (Spagnolo et al, 2015).…”