Production, Biochemical Characterization, and Application of Laccase from Halophilic Curvularia lunata MLK46 Recovered from Mangrove Rhizosphere.

Alshammary, Malak; Kotb, Essam; Ababutain, Ibtisam M.; Alabdalall, Amira H.; Aldakeel, Sumayh A.; Alsanie, Sumayah I.; Alhamad, Salwa; Alshwyeh, Hussah; Albarrag, Ahmed M.

Simple Summary: Industrialization including petrochemical and refinery sectors has adversely affected the quality of many coastal and terrestrial regions in many countries. The industrial effluents have prompted concerns about the health of living organisms and the proper functioning of ecosystem. Our hypothesis is that applying biological agents such as fungal laccases to degrade these contaminants may be a viable way to address this problem because of their adaptability, effectiveness, and low cost. Our results show that the isolated fungus C. lunata MLK46 from a marine environment exhibited exceptional productivity, and its oxidative enzyme demonstrated stability under extreme conditions. It also showed high catalytic efficiency in the degradation of several pollutants, positioning it as an eco-friendly and sustainable alternative to conventional chemical methods for bioremediation and environmental pollution control. Laccase production was evaluated in 108 fungal isolates recovered from the eastern coast of Saudi Arabia, a critical element in environmental biodegradation and biotransformation. The most active isolate was identified as Curvularia lunata MLK46 (GenBank accession no. PQ100161). It exhibited maximal productivity at pH 6.5, 30 °C, and incubation for 5 d, with 1% sodium nitrate and 1% galactose as the preferred nitrogen and carbon sources, respectively. Productivity was enhanced by NaCl, CuSO4, and FeCl3 supplementation, with a maximum at 0.3 mM, 0.2 mM, and 61.7 mM concentrations, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) for the purified enzyme through diethylaminoethyl (DEAE)-Sepharose chromatography revealed a prominent band at 71.1 kDa with maximum activity at pH 6 and stability at pH 6–9. Furthermore, it was optimally active at 50 °C and thermally stable at 50–80 °C with a half-life time (T1/2) of 333.7 min to 80.6 min, respectively. Its activity was also enhanced by many metallic ions, especially Fe3+ ions; however, it was inhibited by Hg2+ and Ag+ ions. The enzyme demonstrated significant degradation of specific substrates such as 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), guaiacol, o-dianisidine, and 2,6-dichlorophenol, with a kinetic efficiency constant which ranged from 40.95 mM−1 s−1 to 238.20 mM−1 s−1. UV spectrophotometry confirmed efficient oxidation peaks by electron transition against guaiacol (at 300 nm), o-dianisidine (at 480 nm), ABTS (at 420 nm), and 2,6-dichlorophenol (at 600 nm). The results collectively demonstrate the potential of laccase from C. lunata MLK46 as a promising agent for the effective biodegradation of several industrial pollutants under extreme conditions.

ENZYME stability; SODIUM dodecyl sulfate; POLYACRYLAMIDE gel electrophoresis; INDUSTRIAL wastes; SUSTAINABILITY; LACCASE

Biology (2079-7737), 2025, Vol 14, Issue 4, p402

2079-7737

Academic Journal

10.3390/biology14040402