Degradation performance and bioinformatic analysis of graphite electrode electrolysis cells for erythromycin fermentation residue

To remove antibiotics and alleviate the resistance threats from the land application of erythromycin fermentation residues, this study evaluated the degradation of erythromycin by an electrolytic cell, focusing on four parameters: reaction time, voltage, electrode distance and initial pH. Metagenome sequencing community composition and resistance gene profile were also examined under optimal conditions. The results showed that the removal rate of erythromycin reached 95.75% under optimal conditions (reaction time: 4 h, voltage: 14 V, electrode distance: 3.72 cm, pH: 4.52). Through dehydration and condensation of erythromycin, mainly under the action of hydroxyl radical, C5-desosamine was mineralized to form inorganic substances such as CO2, H2O and NO2. The relative abundance of macrolide resistance genes was significantly decreased, among which five erm classes were translocated and two were degraded (Isa and mphA). The migration risk of these genes was dominated by transposase tnpA and integrases intl. The relative abundance of Proteobacteria and Actinobacteria exhibited an increasing trend, whereas the abundance of the erythromycin-producing bacterium Saccharopolyspora erythraea were degraded by 97.25–98.67%. These results are expected to provide a basis for the development of new disposal strategies for pharmaceutical waste residues to efficiently remove antibiotics and avoid the spreading of antibiotic resistance genes.