Characterisation of Laccase Isolated from Pleurotus pulmonarius for Antibiotic Degradation Potential
Ikeanyibe Nneoma Collette*, Eze SOO & Omeje KO and Ezike TC
ABSTRACT
The study aimed to characterize a laccase enzyme isolated from the white rot fungi Pleurotus pulmonarius and to evaluate its potential in biodegradation of antibiotics. Laccase was produced by the isolated white rot fungi under solid-state fermentation supplemented with rice bran as the lignocellulosic support. A time-course study for enzyme production indicated that day ten (10) gave the maximum enzyme production. The crude Pleurotus pulmonarius laccase (Ppl) was precipitated by 80 % ammonium sulphate precipitation and purified using a Sephadex G-100 column, which was equilibrated with 0.1 M sodium phosphate buffer (pH 7.0). The optimum pH and temperature of the laccase were 3.5 and 60°C, respectively. The stability of Pleurotus pulmonarius laccase to temperature was studied, at various temperatures of 50, 60, and 70 °C in which the enzyme activity was most stable at 50 °C after incubating for 120 min. Additionally, the enzyme was more stable at a pH of 6.0. The maximum velocity (Vmax) and Michaelis constant (Km) of the enzyme are 3333.33 µmol/ min and 0.6667 µM, respectively using 2,2 azino bis-3-ethylbenzothiozoline-6-sulfonic acid (ABTS) as substrate. Furthermore, metal ions significantly influenced laccase catalytic activity. The effect of some metal ions on the activation of enzyme activity was in the following order Cu2+˃ Mg2+˃ Zn2+ ˃ Mn2+ ˃ Ba2+. The enzyme was characterised and evaluated in vitro for its potential for antibiotic degradation. The spectral studies on the degradation of antibiotics revealed that Pleurotus pulmonarius laccase significantly decreased the absorbance of the antibiotics at their maximum absorption wavelength at different concentrations as the incubation time was increased. Hence, the findings highlight that Pleurotus pulmonarius laccase (Ppl) has the potential for antibiotic degradation, opening new avenues for biotechnological applications. The utilization of enzymatic bioremediation, particularly employing laccases from lignin-degrading fungi such as Pleurotus pulmonarius, offers a promising avenue for targeted degradation of pharmaceutical pollutants. The significance of this research lies in its potential to offer a sustainable and efficient approach to pharmaceutical wastewater treatment, promoting the removal of antibiotics and reducing the risk of antibiotic resistance in the environment. Furthermore, the outcome of this study can contribute to the development of environmentally friendly practices in pharmaceutical industries, fostering a more responsible and eco-conscious approach to wastewater management
