Tiamulin removal by wood-rot fungi isolated from swine farms and role of ligninolytic enzymes

Abstract

Tiamulin (TIA) is a widely used antibiotic in Thai swine farms and persists in swine manure storage. Significant amounts remain in swine manure after composting, posing risks related to the spread of the compound and the evolution of resistant genes when this compost is used as a fertilizer. Therefore, it is necessary to enhance TIA degradation. This study successfully purified TIA-degrading fungi, which have a high capacity for treating antibiotic-contaminated manure. Twelve strains were collected from swine farms and preliminarily examined for their ability to degrade recalcitrant compounds using brilliant green and crystal violet dyes at 0.05% (w/v). Three isolated fungi and three white-rot fungal strains–namely, Lasiodiplodia sp. F1, Fusarium sp. F5, Galactomyces sp. F8, Verticillium sp., Trametes versicolor, and Trametes hirsuta AK4–capable of developing considerable decolorized zones on both dyes exhibited their abilities to degrade 10 mg l−1 of TIA over a period of 12 days: 93.2 ± 0.0%, 82.4 ± 10.2%, 73.8 ± 5.6%, 89.3 ± 0.0%, 86.1 ± 0.0%, and 66.8 ± 4.8%, respectively. Lasiodiplodia sp. F1, Verticillium sp., and Trametes versicolor were able to remove TIA most efficiently (>85%) and have the potential to be applied to swine waste for the elimination of antibiotic substances. Manganese peroxidase (MnP) was predominantly produced; MnP expression was induced by tiamulin, suggesting its main role in TIA degradation.