Laccases as Effective Tools in the Removal of Pharmaceutical Products from Aquatic Systems

Abstract

This review aims to provide a comprehensive overview of the application of bacterial and fungal laccases for the removal of pharmaceuticals from the environment. Laccases were evaluated for their efficacy in degrading pharmaceutical substances across various categories, including analgesics, antibiotics, antiepileptics, antirheumatic drugs, cytostatics, hormones, anxiolytics, and sympatholytics. The capability of laccases to degrade or biotransform these drugs was found to be dependent on their structural characteristics. The formation of di-, oligo- and polymers of the parent compound has been observed using the laccase mediator system (LMS), which is advantageous in terms of their removal via commonly used processes in wastewater treatment plants (WWTPs). Notably, certain pharmaceuticals such as tetracycline antibiotics or estrogen hormones exhibited degradation or even mineralization when subjected to laccase treatment. Employing enzyme pretreatment mitigated the toxic effects of degradation products compared to the parent drug. However, when utilizing the LMS, careful mediator selection is essential to prevent potential increases in environment toxicity. Laccases demonstrate efficiency in pharmaceutical removal within WWTPs, operating efficiently under WWTP conditions without necessitating isolation.

Evaluation of Antibiotic Biodegradation by a Versatile and Highly Active Recombinant Laccase from the Thermoalkaliphilic Bacterium Bacillus sp. FNT

“…In the case of OTC, biotransformation reached 36, 42, and 26% at 40, 30, and 20 • C and pH 6.0, respectively, whereas the enzyme alone reached a maximum of 11% at 20 • C, indicating that FNTL requires the addition of a redox mediator for the removal of OTC. These results are in agreement with previous studies indicating that significant antibiotic elimination by laccases usually requires the involvement of an appropriate mediator [40,82].…”

“…Subsequently, the hydroxyl at C6 was removed to form TC5, which could be further decomposed to produce TC6, TC7, and TC8 [ 89 ]. Similar reactions leading to the formation of degradation products with a smaller molecular size have been reported for biodegradation of TC by fungal laccases, [ 48 , 82 , 87 ].…”

“…Future studies need to be directed towards establishing the nature and toxicity levels of the enzyme-generated degradation products. It has been proposed that a putative mechanism of TC biotransformation by laccases involves the opening of the aromatic ring to form small acidic molecules, which results in a loss of antibiotic activity [ 82 ]. The main transformation products of TC biodegradation by the action of the bacterial laccase from B. amyloliquefaciens have been identified by LC-MS, and the authors proposed three putative pathways for TC degradation [ 89 ].…”

Antibiotics: environmental impact and degradation techniques

“…Finally, it was found that this rate varied between 26.0% and 48.4% for antibiotics included in the tetracycline group, such as oxytetracycline, chlortetracycline, doxycycline, and tetracycline. These differences between the removal rates are thought to be due to the molecular structure of antibiotics [71,72]. However, the use of enzyme-based techniques also presents limitations.…”