Degradation of Erythromycin by a Novel Fungus, Penicillium oxalicum RJJ-2, and the Degradation Pathway

Abstract

This study aimed to isolate effective erythromycin-degrading fungi and determine the characteristics and pathway of degradation. Erythromycin-degrading fungi were isolated from erythromycin-contaminated samples using a standard enrichment and isolation method. The degradation characteristics were investigated in mineral salt medium (MSM) with erythromycin as a sole carbon source. Key degradation intermediates were analyzed by high performance liquid chromatography–mass spectrometry (HPLC–MS) and used to deduce the erythromycin degradation pathway of strain RJJ-2. A novel erythromycin-degrading fungus RJJ-2, was isolated from a contaminated sample. Based on its morphology and internal transcribed spacer (ITS) sequence, the strain was 100% similar to P. oxalicum (MN759650) and named P. oxalicum RJJ-2. The strain RJJ-2 degraded 84.88% erythromycin after 96-h incubation at 35 °C and pH 6.0 in MSM with erythromycin (100 mg L−1) as the sole carbon source. Optimal degradation conditions for P. oxalicum RJJ-2 were 35 °C, and pH 6.0 with 0.1% ammonium sulfate supplementation. HPLC–MS analysis indicated that the main degradation intermediates were 3-depyranosyloxy erythromycin A, cladinose, desosamine, and 7,12-dyhydroxy-6-deoxyerythronolide B. It was inferred that the erythromycin was degraded to 3-depyranosyloxy erythromycin A by a glycoside hydrolase in the initial reaction. This study demonstrated that P. oxalicum RJJ-2 is a novel erythromycin-degrading strain, which can provide a new eco-friendly and cost-effective approach for the disposal of erythromycin fermentation wastes and other hazardous chemicals.