Biosorption and biotransformation behaviours of veterinary antibiotics under aerobic livestock wastewater treatment processes

Biotransformation of minocycline by a novel strain Kluyvera sp. DM13 isolated from municipal sludge: Performances, removal pathways, and toxicity

Minocycline has been widely used in clinical treatment and its residues were considered to have environmental safety risks due to complex chemical structure. Therefore, it is necessary to find an efficient and environmentally friendly method to remove minocycline from the environment. This study screened and isolated a minocycline degrading strain DM13 from the activated sludge for municipal sewage pipeline, and optimized the biodegradation of minocycline by DM13 under various environmental conditions. The maximum biodegradation efficiency of 50 mg/L minocycline reached 93 % at 72 h with the temperature of 30 °C, the initial pH of 7.0, and the inoculation rate of 3 %. Two potential biotransformation pathways were proposed, including deamination, demethylation, and decarbonylation. The acute toxicity assessment showed that the biotransformation products of minocycline had lower toxicity than the parent compound. In addition, the first-generation tetracycline antibiotics could be removed, suggesting that strain DM13 has the potential for application in treating antibiotic wastewater.

Removal of sulfonamide antibiotics by constructed wetland substrate with NaOH-modified corn straw biochar under different operating conditions

This study examined the elimination of sulfonamide antibiotics (SAs) by constructed wetland substrates with NaOH-modified corn straw biochar and assessed the impact of environmental conditions on the effectiveness of SAs removal. The study demonstrated that the constructed wetland substrate with NaOH-modified biochar significantly eliminated eight SAs, with a removal rate of over 94 %. During the removal process, the intermediates will undergo regeneration of the parent compounds under low DO concentrations. This was based on the linear stepwise regression analysis and Geodetector models. The results showed that SA types COD, NH4+-N, TN, and DO had a stronger influence. The dominant bacteria in the constructed wetland system were mainly affected by antibiotic concentration, DO, NH4+-N and NO3--N, which affected the removal of antibiotics. Overall, the constructed wetland substrate with NaOH-modified corn straw biochar can be effectively employed as an ecological method for eliminating SAs from the environment.

Hyperbranched Polylysine Exhibits a Collaborative Enhancement of the Antibiotic Capacity to Kill Gram-Negative Pathogens

In recent years, traditional antibiotic efficacy outcomes have rapidly diminished due to the advent of drug resistance, and the dose limitation value has increased due to the severe side effect of globalized healthcare. Therefore, novel strategies are required to resensitize resistant pathogens to antibiotics existing in the field and prevent the emergence of drug resistance. In this study, cationic hyperbranched polylysine (HBPL-6) was synthesized using the one-pot polymerization method. HBPL-6 exhibited excellent non-cytotoxicity and bio-solubility properties. The present study also showed that HBPL-6 altered the outer membrane (OM) integrity of Escherichia coli O157:H7, Salmonella typhimurium, and Pseudomonas aeruginosa PAO1 by improving their permeability levels. When administered at a safe dosage, HBPL-6 enhanced the accumulation of rifampicin (RIF) and erythromycin (ERY) in bacteria to restore the efficacy of the antibiotics used. Moreover, the combination of HBPL-6 with colistin (COL) reduced the antibiotic dosage, which was helpful in preventing further drug-resistance outcomes. Therefore, this research provides a new strategy for reducing the dosage of drugs used to combat Gram-negative (G-) bacteria through their synergistic effects.