Laccases are versatile and relatively accessible catalysts with practical/industrial applications. Their proteic nature entails limited stability under non-native conditions, especially such as those that would be required for industrial applications. Here, derivatization of a laccase from Sclerotinia sclerotiorum is reported, using an (methyl-PEG12)3-PEG4) N-succinimide ester in order to improve the thermostability of the enzyme. The PEGylated laccase is characterized using gel electrophoresis, size-exclusion chromatography, catalytic parameters and thermal stability. A 50% increase in residual activity after incubation at 50°C for up to two hours was achieved for the PEGylated laccase compared to the native enzyme.

Industrialization, intensive farming, rapid population growth and urbanization are the source of a large number of pollutants entering the environment. The current concentration of xenobiotics released into the environment exceeds its natural ability to decompose them. Enzymatic degradation of pollutants seems to be an environmentally friendly process. Due to the wide spectrum of substrate specificity, from inorganic compounds to high molecular weight organic compounds such as PAH or dyes, as well as favorable biochemical properties, laccase has been used in the biological removal of xenobiotics from the environment. It is important to understand the degradation mechanisms of pollutants and to evaluate the final products in terms of their toxicity. The laccase oxidizes the substrates with the simultaneous reduction of molecular oxygen to water, which is the purest reaction co-substrate. That is why it is called a green biocatalyst. The trend is an increase in the production of enzymes related to the intensive development of industry, bioremediation or synthetic chemistry. This leads to the search for laccases with greater activity and stability under extreme conditions. The potential of laccases to degrade xenobiotics can be promoted by improving enzymatic catalytic characterization using protein engineering and other genetic engineering methods.

The primary contributor to global warming has been the careless usage of fossil fuels. Urbanization's threat to the depletion of these resources has made it necessary to find alternatives due to the rising demand. Four different forms of biofuels are now available and constitute a possible replacement for fossil fuels. The first generation of biofuels is generated from the edible portion of biomass, the second generation is made from the non-edible portion of biomass, the third generation is made from algal biomass, and the fourth generation is made using molecular biology to improve the algal strain. Second generation biofuels are extremely important because they are derived from non-edible biomass, such as agricultural and agro-industrial wastes rich in cellulose, hemicellulose, pectin, and starch impregnated with lignin, and are hydrolyzed after delignification by physio-chemical or biological pretreatments using ligninases. There has been a lot of research on their production using chemical and enzymatic hydrolysis, but it has not been economically viable in comparison to first generation biofuels due to the formation of several inhibitors with chemical hydrolysis and the high cost of the enzymes. Furthermore, the need for multiple enzymes due to the various types of carbohydrates in the feedstocks makes the enzymatic process too expensive. This article examines the enzymes involved in the hydrolysis of feedstocks for the production of second generation bioethanol, a highly acceptable biofuel.

The over use of pharmaceutical compounds, essentially antibiotics, led to an increase of their concentrations in aquatic ecosystems. In this study, the white-rot fungus Coriolopsis gallica (high-laccase-producing fungus) was investigated for the biodegradation of ampicillin (AMP) under different cultivation conditions. The biotransformation of the antibiotic was confirmed by means of high-performance liquid chromatography (HPLC), and the antibacterial activity was evaluated via the bacterial growth inhibition agar well diffusion method using Escherichia coli as an ampicillin-sensitive test strain. The results showed that AMP (50 mg L-1) was totally removed by C. gallica after 6 days of incubation in a liquid medium. The antibiotic removal rate was maximal with a fungal culture aged 9 days. Such a culture achieved the removal of a higher concentration of up to 500 mg L-1 of ampicillin in 3 days. This higher antibiotic removal rate was concomitant with the maximal laccase production in culture supernatant. In addition, four consecutive doses of 500 mg L-1 of ampicillin were transformed by the same fungal culture in 24 days. After that, the fungus was unable to remove the antibiotic. The measurement of ligninolytic enzyme activity showed that laccase of C. gallica might participate in the biotransformation of AMP.

We studied the capacity of glutathione and a specific inactivated dry yeast rich in glutathione to protect white grape must from browning compared to using sulphur dioxide. The results indicate that sulphur dioxide drastically reduces the oxygen consumption rate, protects hydroxycinnamic acids from oxidation and prevents grape must against browning even in the presence of laccase. Glutathione, pure or in the form of a specific inactivated dry yeast rich in glutathione, also reduces the oxygen consumption rate but to a lesser extent than sulphur dioxide. It favours the formation of GRP from hydroxycinnamic acids and effectively protects grape must against browning in healthy grape conditions. Nevertheless, in the presence of laccase it was not effective enough. Therefore, both forms of glutathione can be considered as interesting alternative tools to sulphur dioxide for preventing browning in white grape must, but only when the grapes are healthy.

The textile industry produces high volumes of colored effluents that require multiple treatments to remove non-adsorbed dyes which could be recalcitrant due to their complex chemical structure. Most of the studies have dealt with the biodegradation of mono or diazo dyes but rarely with poly-azo dyes. Therefore, the aim of this paper was to study the biodegradation of a four azo-bond dye (Sirius grey) and to optimize its decolorization conditions. Laccase-containing cell free supernatant from the culture of a newly isolated fungal strain, Coriolopsis gallica strain BS9, was used in the presence of 1-hydroxybenzotriazol (HBT) to optimize the dye decolorization conditions. A Box-Benken design with 4 factors namely: pH, enzyme concentration, HBT concentration and dye concentration, was performed to determine optimal conditions for the decolorization of Sirius grey. The optimal conditions were pH 5, 1 U/mL of laccase, 1 mM of HBT, and 50 mg/L of initial dye concentration ensuring a decolorization yield and rate of 87.56 % and 2.95 %/min respectively. Decolorized dye solution showed a decrease of its phytotoxicity (Germination index GI = 80 %) compared to the non-treated solution (GI = 29 %). This study suggests that laccase-mediator system could be a promising alternative for dyes removal from textile wastewaters.

Although laccase has been recognized as a wonder molecule, and green enzyme, the use of low yielding fungal strains, poor production, purification, and low enzyme kinetics have hampered its larger-scale applications. Hence the present research was aimed to select high yielding fungal strains and to optimize the production, purification, and kinetics of laccase of Aspergillus sp. HB_RZ4. Aspergillus sp. HB_RZ4 produced a copious amount of laccase on under meso-acidophillic shaking conditions in a medium containing glucose and yeast extract. A 25 µM of CuSO4 enhanced the enzyme yield. The enzyme was best purified on Sephadex G-100 column. Purified enzyme resembled with the laccase of A. flavus. Kinetics of purified enzyme revealed the high substrate specificity and good velocity of reaction with ABTS as substrate. The enzyme was stable over a wide range of pH and temperature. The peptide structure of the purified enzyme resembled with the laccase of A. kawachii IFO 4308. The fungus decolorized various dyes independent of the requirement of a laccase mediator system (LMS). Aspergillus sp. HB_RZ4 came out as a potent natural producer of laccase, it decolorized the dyes even in absence of LMS and thus can be used for bioremediation.

Alginate is naturally occurring polymer derived from brown algae biomass, which has found numerous applications in various fields. Chemical modification of alginate is widely used to improve the physicochemical properties of alginate and to provide new potential for various applications. In this article, we modified alginate with L-DOPA, using periodate oxidation and reductive amination, in order to be get more suitable biopolymer for biocatalysts immobilization and hydrogel formation. Obtained modified alginate was used for immobilization of laccase on cell walls. For this purpose, laccase from Streptomyces cyaneus was expressed on the surface of Saccharomyces cerevisiae EBY100 cells. Obtained cell wall laccase was immobilized within L-DOPA-alginate beads, by crosslinking of L-DOPA-alginate with calcium ions and laccase. The effect of additional crosslinking of beads by green light induced photopolymerization with eosin Y was investigated. The immobilized laccase systems were used for dye decolorization and also investigated in multiple treatment processes of dye decolorization. Beads with L-DOPA-alginate with higher degree of modification (5.0 mol%) showed higher enzymatic activity and better de-colorization efficiency compared to those with lower degree of modification (2.5 mol%). Obtained immobilized biocatalysts are suitable for the decolorization of dye Evans Blue due to their high efficiency and reusability.

White-rot fungi (WRF) have specific enzymes to degrade lignocellulosic and phenolic compounds. Therefore, their direct application could be an alternative to biodegrade complex lignocellulosic biomass such as olive mill solid waste (OMSW). The aim of this study was to evaluate the capacity of A. discolor and S. hirsutum to grow in OMSW as the sole substrate under static conditions and evaluate the phenolic removal compounds and lignin degradation. The lignolytic enzyme activity was determined, as was the phenolic compound removal. At the same time, lignin degradation and structural changes were evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscope (SEM), respectively. Both strains were able to grow using OMSW as the sole substrate without adding other nutrients, oxygen and/or agitation. The higher ligninolytic enzyme activity was found at day 8, and the highest phenolic removal (more than 80% with both strains) was reached after 24 days of incubation. The CLSM analysis confirmed lignin degradation through the drop in lignin fluorescence from 3967 for untreated OMSW to 235 and 221 RFU after 24 days of treatment by A. discolor and S. hirsutum respectively. The results indicate that both WRF could be suitable candidates to design an in-situ pretreatment step of OMSW, as long as in future research the WRFs have the same performance in non-sterile conditions.