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Biotransformation of the Fluoroquinolone Antibiotic, Levofloxacin, by the Free and Immobilized Secretome of Coriolopsis gallica

Summary

Researchers discovered that a type of fungus called Coriolopsis gallica can break down the antibiotic levofloxacin, which persists in the environment and contributes to antibiotic resistance. They tested both free enzymes from the fungus and enzymes trapped in alginate beads to see which worked better. The study found that free enzymes degraded more of the antibiotic when a chemical helper molecule called HBT was added, while immobilized enzymes were more stable and could be reused multiple times.

Background

Fluoroquinolone antibiotics are widely used in medical and veterinary applications but persist in the environment due to low biotransformation rates. Conventional water treatment methods are ineffective or economically unsustainable. White-rot fungi like Coriolopsis gallica possess lignin-modifying enzymes that can degrade various recalcitrant compounds including fluoroquinolone antibiotics.

Objective

This study aimed to optimize the efficiency of levofloxacin biotransformation by the secretome of Coriolopsis gallica by evaluating physicochemical parameters and comparing free versus immobilized enzyme systems. The research investigated the effect of mediator concentration, enzyme concentration, temperature, and pH on the biotransformation process.

Results

Free secretome achieved 50% removal of 50 mg L⁻¹ levofloxacin in the presence of 2.5 mM HBT mediator after 24 hours. Immobilized secretome removed only 10 mg L⁻¹ but was reusable and showed greater thermal stability. MS analysis confirmed levofloxacin was transformed into N-oxide levofloxacin and a derivative with an amine replacing the piperazine cycle.

Conclusion

The study demonstrates that C. gallica secretome effectively biotransforms levofloxacin, with optimal conditions at pH 5-6, 40-50°C depending on immobilization status, and 2.5 mM HBT concentration. Immobilization provides greater stability and reusability advantages despite lower degradation rates, making it promising for practical bioremediation applications. Laccases appear to be the primary enzymes responsible for the biotransformation.
  • Published in:Journal of Fungi,
  • Study Type:Experimental Laboratory Study,
  • Source: PMID: 39728357
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