The global rise in urbanization and industrial activity has led to the production and incorporation of foreign contaminant molecules into ecosystems, distorting them and impacting human and animal health. Physical, chemical, and biological strategies have been adopted to eliminate these contaminants from water bodies under anthropogenic stress. Biotechnological processes involving microorganisms and enzymes have been used for this purpose; specifically, laccases, which are broad spectrum biocatalysts, have been used to degrade several compounds, such as those that can be found in the effluents from industries and hospitals. Laccases have shown high potential in the biotransformation of diverse pollutants using crude enzyme extracts or free enzymes. However, their application in bioremediation and water treatment at a large scale is limited by the complex composition and high salt concentration and pH values of contaminated media that affect protein stability, recovery and recycling. These issues are also associated with operational problems and the necessity of large-scale production of laccase. Hence, more knowledge on the molecular characteristics of water bodies is required to identify and develop new laccases that can be used under complex conditions and to develop novel strategies and processes to achieve their efficient application in treating contaminated water. Recently, stability, efficiency, separation and reuse issues have been overcome by the immobilization of enzymes and development of novel biocatalytic materials. This review provides recent information on laccases from different sources, their structures and biochemical properties, mechanisms of action, and application in the bioremediation and biotransformation of contaminant molecules in water. Moreover, we discuss a series of improvements that have been attempted for better organic solvent tolerance, thermo-tolerance, and operational stability of laccases, as per process requirements.

In this study, the purification and characterization of two thermostable laccases produced by Pycnoporus sanguineus CS43 (LacI and LacII) were performed. Also, their biotechnological potential was assessed through the degradation of endocrine disrupting chemicals (EDCs). Laccases were purified by ultrafiltration, ion exchange (IEX) and hydrophobic interaction chromatography achieving specific activities close to 285Umg−1. The molecular weights of LacI and LacII, determined by SDS-electrophoresis, were 68 and 66kDa, respectively. Both laccases showed high amino acid sequence similarity (91%) between them and high thermostability, at 50 and 60°C (half-lives of 277.7 and 18h for LacI, 35.8 and 2.25h for LacII). The isoforms oxidized common laccase substrates such as 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonate (ABTS), 2,6-dimethoxyphenol (DMP) and guaiacol at acidic pH conditions. ABTS was the most efficient substrate, showing high specificity constants of 74,816 and 36,746mM−1s−1 for Lac I and LacII, and Michaelis constants (Km) of 6.9 and 12.2μM respectively at pH 3. Both purified laccases remained active at high concentrations of organic solvents (acetonitrile, ethanol and acetone), with an IC50 (v/v) of >64%, 55% and 47% for LacI, and 33%, 52% and 31% for LacII, respectively. LacI and LacII were tested to degrade EDCs, nonylphenol and triclosan, with more than 95% removal after 8h of treatment with 100U/L at pH 5 as determined by means of HPLC. The high thermostability, unique Michaelis–Menten kinetic parameters, and organic solvent tolerance demonstrated for the isoforms produced by P. sanguineus CS43 render them promising candidates for industrial applications. LacI exerted a higher thermal and pH stability, tolerance against inhibitors and was a more efficient catalyst for ABTS and DMP than LacII

The aim of the research was to determine the impact of fermentation with Pleurotus ostreatus on kidney beans, black beans, and oats. The results indicate that the fungus has a positive effect on the substrates when compared to the controls. The antioxidant activity (39.5% on kidney beans and 225% on oats in relation to the controls) and content of total polyphenols (kidney beans three times higher regarding the controls) increased significantly by the presence of the fungus mycelium, even after simulated digestion. There was a significant increase in protein digestibility (from 39.99 to 48.13% in black beans, 44.06 to 69.01% in kidney beans, and 63.25 to 70.01% in oats) and a decrease of antinutrient tannins (from 65.21 to 22.07 mg in black beans, 35.54 to 23.37 in kidney beans, and 55.67 to 28.11 in oats) as well as an increase in the contents of some essential amino acids. Overall, this fermentation treatment with Pleurotus ostreatus improved the nutritional quality of cereals and legumes, making them potential ingredients for the elaboration and/or fortification of foods for human nutrition.

The biodegradation of organic compounds present in water at trace concentration has become a critical environmental problem. In particular, enzymatic oxidation by fungal laccases offers a promising alternative for efficient and sustainable removal of organic pollutants in water. In this work, the biocatalytic ability of laccases from the Pycnoporus sanguineus CS43 fungus was evaluated. A filtered culture supernatant (laccase cocktail) evidenced an enhanced biotransformation capability to remove common endocrine-disruptor compounds (EDCs), such as bisphenol A, 4-nonylphenol, 17-α-ethynylestradiol and triclosan. A biodegradation of around 89–100 % was achieved for all EDCs using synthetic samples (10 mg L⁻¹) and after the enzymatic treatment with 100 U L⁻¹ (50.3 U mg ⁻¹). The biodegradation rates obtained were fitted to a first order reaction. Furthermore, enzymatic biocatalytic activity was also evaluated in groundwater samples coming from northwestern Mexico, reaching biotransformation percentages between 55 and 93 % for all tested compounds. As far as we know this is the first study on real groundwater samples in which the enzymatic degradation of target EDCs by a laccase cocktail from any strain of Pycnoporus sanguineus was evaluated. In comparison with purified laccases, the use of cocktail offers operational advantages since additional purification steps can be avoided.

In this work, the biocatalytic ability of laccases from filtered culture supernatant of Pycnoporus sanguineus was evaluated without mediators and under mild reaction conditions. This 100 U L −1 laccase cocktail removed 50% Diclofenac, 97% β-Naphthol and 71% 2,4 Dichlorophenol within 8 h of reaction and 78% for 5,7-Diiodo-8-hydroxyquinoline within 3.5 h; at initial concentrations of 10 mg L−1 and at 25 °C. Furthermore, this enzyme cocktail also removed in excess of 53% all tested compounds in a real groundwater sample from northwestern Mexico. In comparison with purified laccases, the use of cocktail offers operational advantages since additional purification steps can be avoided