Abstract
In recent years, an increasing number of lakes and soils around the world have been polluted by antibiotics, seriously threatening the ecological balance and human health. Currently, there is a lack of understanding of the biodegradation mechanism of typical antibiotics by microorganisms. In this study HD1, a novel Bacillus sp. strain called capable of effectively degrading ofloxacin (OFL), a typical antibiotic with a high detection rate in the environment, was isolated from soil contaminated by OFL. The results of single-factor experiments showed that the optimal conditions for OFL degradation included 30°C, pH 7.0, and 10 g L–1 NaCl. After 7 days of incubation under aerobic conditions, the degradation efficiency of OFL (5 mg L–1) was about 66.2%. Five degradation products were detected by LC-MS analysis, and it was deduced that the possible degradation pathways of OFL included the oxidation of the piperazine ring, demethylation, hydroxylation, and methoxy cleavage. Metabolomics analysis indicated that key pathways with the highest difference with HD1 metabolites included the phenylalanine, arginine, and proline metabolism pathways. By regulating energy, amino acid metabolism, and carbohydrate metabolism, HD1 could alleviate OFL stress to degrade better. This study explored the degradation mechanism of OFL by HD1 and provides a theoretical basis and technical support for the remediation of OFL-contaminated environments by functional microorganisms.
Highlights
Ofloxacin (OFL), a third-generation fluoroquinolone (FQ) antibiotic, is internationally recognized as an extremely important broad-spectrum antimicrobial agent that is widely used for the clinical treatment of infections and diseases caused by Gram-negative bacteria (Aggio et al, 2010)
The results showed that the toxic effect of DDT was significantly dose-dependent, while the presence of microplastics weakened the response of DDT to the growth and metabolism of E. coli
Five strains of OFL-resistant bacteria were obtained after 3 ∼ 4 purification cycles, which were labeled HD1, HD2, HD3, HD4, and HD5, respectively
Summary
Ofloxacin (OFL), a third-generation fluoroquinolone (FQ) antibiotic, is internationally recognized as an extremely important broad-spectrum antimicrobial agent that is widely used for the clinical treatment of infections and diseases caused by Gram-negative bacteria (Aggio et al, 2010). Aqueous environments around the world have increasingly been polluted by FQs (Karthikeyan and Meyer, 2006; Yang et al, 2018). As a semi-synthetic antibiotic, the stable chemical properties of OFL make it resistant to biodegradation even after decades (Schulz et al, 2019). Due to its high solid-water partition coefficient, it is enriched on the surface of various stable environmental particle carriers, including atmospheric dust, soil particles, and aqueous sediments (Golet et al, 2003; Zhao et al, 2016; Reis et al, 2020). Accumulation and retention of antibiotics in the environment can promote the selection of resistance genes in bacterial populations and affect the dynamics of biological populations followed by entering the human body through the biological chain, which may lead to high risks for ecosystems and human health (Xu et al, 2015; Yang et al, 2018).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
