Increased production of laccase by pellets of Funalia trogii ATCC 200800 and Trametes versicolor ATCC 200801 in repeated-batch mode

Laccase immobilization and its degradation of emerging pollutants: A comprehensive review

The chronic lack of effective disposal of pollutants has resulted in the detection of a wide variety of EPs in the environment, with concentrations high enough to affect ecological health. Laccase, as a versatile oxidase capable of catalyzing a wide range of substrates and without producing toxic by-products, is a potential candidate for the biodegradation of pollutants. Immobilization can provide favorable protection for free laccase, improve the stability of laccase in complex environments, and greatly enhance the reusability of laccase, which is significant in reducing the cost of industrial applications. This study introduces the properties of laccase and subsequently elaborate on the different support materials for laccase immobilization. The research advances in the degradation of EDs, PPCPs, and PAHs by immobilized laccase are then reviewed. This review provides a comprehensive understanding of laccase immobilization, as well as the advantages of various support materials, facilitating the development of more economical and efficient immobilization systems that can be put into practice to achieve the green degradation of EPs.

Enhanced laccase activity in Trametes versicolor (L.: Fr.) Pilát by host substrate and copper

Laccases are appealing biocatalysts for various industrial utilizations. The fungus Trametes versicolor (L.: Fr.) Pilát causes white rot in wood and has been identified as an important fungal laccase producer. To investigate laccase production and activity in T. versicolor, the native isolate was collected from the host (Quercus castaneifolia) in the forests of Guilan province, northern Iran, and then purified and identified using the molecular marker. Its ability to produce laccase enzyme in the presence of different plant substrates including sawdust and wood chips of oak, poplar, and pine was evaluated. Also, the effect of copper as an enzyme inducer was investigated in vitro. The results showed that adding the wood to the culture medium increased laccase production, and among these, oak sawdust had the greatest effect, a 1.7-fold increase from that in the control (4.8 u/l vs. 2.8 u/l). Also, the enzyme extraction time effect on the optimal recovery yield showed that the 5-h enzyme extraction cycle resulted in the highest yield of the enzyme (18.97 u/l). Moreover, adding different concentrations of copper to the fungal culture medium increased the production of laccase, and the highest amount of enzyme (92.04 u/l) was obtained with 3.5 mM of CuSO4 along with oak sawdust. Based on the results, the addition of host wood sawdust ("oak" in this work) and copper particles together stimulates the fungal growth and the laccase production during submerged cultivation of T. versicolor. Therefore, it would be a safe and cheap strategy for the commercial production of laccase by filamentous fungi.

Optimization of biodegradation yield of reactive blue 49: An integrated approach using response surface methodology based marine predators algorithm

Biodegradation involving the use of biological systems are proving to be more cost-effective, energy efficient and environmentally friendly method for treatment with dye. There are also some advantages of enzymatic degradation to remove pollutants from textile effluents. They are specific and selectable for the substrates. Moreover, the usage of enzymatic degradation with laccase has environmental and social dimensions of sustainable bio-economy when compared with commercial solutions. In this study, besides the conventional RSM (Response Surface Methodology) approaches, the performance of a new metaheuristic, MPA (Marine Predators Algorithm) integrated with RSM has also been tested. The effect of four independent variables time, enzyme amount, agitation speed, and initial dye concentration have been studied to obtain maximum decolorization. Two major techniques of RSM, namely Box Behnken Design (BBD) and Central Composite Design (CCD) have been used to determine optimal levels of parameters. The highest decolorization efficiency (%) of Reactive Blue 49 (RB49) has been achieved as 92.82% with BBD and 90.56% with CCD. Maximum efficiency for BBD based MPA as being 94.69% has been obtained at 70.96 min, 1.5 mL, 74.63 rpm, and 99.09 ppm. For CCD based MPA, the level of efficiency has been obtained as 93.1% at 39.69 min, 1 mL, 72.07 rpm, and 74.41 ppm. The results of MPA indicate that using metaheuristics combined with RSM is a suitable and sustainable way to optimize parameters of RB49% for decolorization.

Tailor-made novel electrospun polycaprolactone/polyethyleneimine fiber membranes for laccase immobilization: An all-in-one material to biodegrade textile dyes and phenolic compounds

In spite of many works on the biodegradation of textile dyes and phenolic compounds, we propose a new, inexpensive, environmentally friendly, and sustainable material based on electrospun fiber and immobilized laccase. The polycaprolactone (PCL)/polyethyleneimine (PEI) electrospun fibers were optimized and prepared by electrospinning technique according to the operational parameters like PCL concentration (12 wt%), PEI concentration (10 wt%), voltage (16 kV), needle tip-collector distance (20 cm), and injection speed (0.7 mL/h). Next, characterization studies were performed to investigate the morphology and structure of the electrospun fibers without and with laccase. The crude laccase was obtained by cultivating the white rot fungus T. trogii (TT), and T. versicolor (TV). The resulting electrospun fibers showed a smooth surface with a mean diameter of around 560 nm, and larger diameters were observed after laccase immobilization. According to the results, immobilization increased the stability properties of laccase such as storage, and operational. For instance, the residual activity of the PCL/PEI/TTL and PCL/PEI/TVL after 10 repeated cycles, was 33.2 ± 0.2% and 26.0 ± 0.9%, respectively. After 3 weeks of storage, they retained around 30% of their original activity. Moreover, the PCL/PEI/TTL and PCL/PEI/TVL were found to possess high decolorization yield to remove Orange II and Malachite Green textile dyes from solutions imitating polluted waters. Among them, the PCL/PEI/TTL exhibited the highest decolorization efficiencies of Orange II and Malachite Green after 8 continuous uses at pH 5 and a temperature of 50 °C, reaching over 86%, and 46%, respectively. Moreover, PCL/PEI/TTL and PCL/PEI/TVL effectively degraded the 2,6-dichlorophenol phenolic compound at an optimal pH and temperature range and exhibited maximum removal efficiency of 52.6 ± 0.1% and 64.5 ± 7.6%, respectively. Our approach combines the advantageous properties of electrospun fiber material and immobilization strategy for the efficient use of industrial scale important enzymes such as laccase in various enzymatic applications.

Impact of textile dyes on health and ecosystem: a review of structure, causes, and potential solutions

The rapid growth of population and industrialization have intensified the problem of water pollution globally. To meet the challenge of industrialization, the use of synthetic dyes in the textile industry, dyeing and printing industry, tannery and paint industry, paper and pulp industry, cosmetic and food industry, dye manufacturing industry, and pharmaceutical industry has increased exponentially. Among these industries, the textile industry is prominent for the water pollution due to the hefty consumption of water and discharge of coloring materials in the effluent. The discharge of this effluent into the aquatic reservoir affects its biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), and pH. The release of the effluents without any remedial treatment will generate a gigantic peril to the aquatic ecosystem and human health. The ecological-friendly treatment of the dye-containing wastewater to minimize the detrimental effect on human health and the environment is the need of the hour. The purpose of this review is to evaluate the catastrophic effects of textile dyes on human health and the environment. This review provides a comprehensive insight into the dyes and chemicals used in the textile industry, focusing on the typical treatment processes for their removal from industrial wastewaters, including chemical, biological, physical, and hybrid techniques.

Laccase Production of Newly Isolated Trametes versicolor under Batch, Repeated-Batch, and Solid-State Fermentation Processes

In this study, the laccase production ability of the newly isolated Trametes versicolor strain was investigated in three different fermentation processes. In all three fermentation processes, the fungus was able to produce the laccase enzyme. During the solid-state fermentation process 13.21 U/mL laccase activity was detected on the 20th day in the 10 mM copper-containing medium, while this value reached to 27.30 U/mL in the medium containing 0.5 mM ABTS+10 mM copper. During the liquid batch fermentation process, laccase activity was significantly induced in the medium containing 1 mM copper and the laccase activities reached 2.25, 19.83 and 24.57 U/mL compared to the medium without copper on the 3rd, 6th, and 9th days, respectively. ABTS and xylidine induced the laccase production of this strain at a much lower level than copper. The liquid repeated-batch process also significantly induced the laccase production. While low level of enzyme activities were detected in a copper-free medium, laccase activities were induced in the copper-containing medium and the activity increased from 0.66 U/mL to 9.87 U/mL at the 6th use of the pellets. Copper was detected as an effective inducer for laccase production in all fermentation processes and activity staining after native polyacrylamide gel electrophoresis clearly showed the active laccase bands. The results revealed that this strain is a good laccase producer and the laccase production yield varies depending on the fermentation process, production time, and inducer used.

Screening and production of a potential extracellular fungal laccase from Penicillium chrysogenum: Media optimization by response surface methodology (RSM) and central composite rotatable design (CCRD)

This paper describes the isolation of potent extracellular-laccase producing white-rot fungus, identified by 18 s-rRNA as Penicillium-chrysogenum and its medium optimization by central-composite-rotatable-design using RSM. The optimum laccase-activity of 6.0 U ml-1 was obtained and maximum activity of 7.9 U ml-1 was achieved by statistical-optimization of the medium at 32 °C for 5 days. The molecular-weight of the laccase was found to be 67 kDa. UV-visible absorption-spectrum analysis shows peak at 600 nm and 325 nm corresponding to the type-I Cu(II) & type-III binuclear Cu(II) pair respectively confirming presence of laccase. The sharp endothermic peak at 150 °C and three-phases of protein denaturation was observed by DSC and TGA analysis for enzyme protein. The FT-IR analysis of laccase shows band at 1405cm-1, 1656 cm-1 &3400cm-1 corresponding to amide-I band, amide-II band and amino-acid group respectively. Results of the study show the enzyme is capable of carrying-out hydrolytic-cleavage of chemical-pollutants from the industrial waste-water for providing sustainable-greener environment.

Determination of the effect of RBBR on laccase activity and gene expression level of fungi in lichen structure

This study provides information about the differential transcription regulation of laccase genes in response to RBBR dye. To this purpose, we determined the laccase gene expression, laccase activity, and protein profile of lichen-forming fungi supported to RBBR dye. For those obtained from optimal laccase genes expression profiles, we modified different RNA extraction protocols to obtain high quality and quantity RNA to be used in downstream applications in lichen-forming fungus. We also determined the expression of ten laccase genes in response to RBBR dye by qRT-PCR and validated protein profile. As a result of our study, a high laccase activity of 522 U mL^-1 was obtained after submerged fermentation for 17 days. The maximal laccase activity to RBBR dye was obtained at 408 h. The expression profiles of laccase gene expression on ten laccase genes showed up- or down-regulation in course of eight fermentation times. The most up-regulated gene during the process was lac8. However, poxa1b gene expression was lowest in lichen-forming fungi biomass supplemented with RBBR dye. This study has revealed the influence of RBBR dye on laccase activity levels and the determination of gene expression levels in lichen-forming fungi.

The morphology of Ganoderma lucidum mycelium in a repeated-batch fermentation for exopolysaccharide production

The morphology of Ganoderma lucidum BCCM 31549 mycelium in a repeated-batch fermentation (RBF) was studied for exopolysaccharide (EPS) production. RBF was optimised for time to replace and volume to replace. G. lucidum mycelium showed the ability to self-immobilise and exhibited high stability for repeated use in RBF with engulfed pellets. Furthermore, the ovoid and starburst-like pellet morphology was disposed to EPS production in the shake flask and bioreactor, respectively. Seven RBF could be carried out in 500 mL flasks, and five repeated batches were performed in a 2 L bioreactor. Under RBF conditions, autolysis of pellet core in the shake flask and shaving off of the outer hairy region in the bioreactor were observed at the later stages of RBF (R4 for the shake flask and R6 for the bioreactor). The proposed strategy showed that the morphology of G. lucidum mycelium can withstand extended fermentation cycles.

Immobilization of Trametes versicolor cultures for improving laccase production in bubble column reactor intensified by sonication

The mycelia of Trametes versicolor immobilized in alginate beads provided higher laccase production than that in pelleted form. An efficient ultrasonic treatment enhanced laccase production from the immobilized T. versicolor cultures. The optimized treatment process consisted of exposing 36-h-old bead cultures to 7-min ultrasonic treatments twice with a 12-h interval using a fixed ultrasonic power and frequency (120 W, 40 kHz). Using the intensification strategy with sonication, laccase production increased by more than 2.1-fold greater than the untreated control in both flasks and bubble column reactors. The enhancement of laccase production by ultrasonic treatment is related to the improved mass transfer of nutrients and product between the liquid medium and the gel matrix. These results provide a basis for the large-scale and highly-efficient production of laccase using sonobioreactors.

Ultrasound-intensified laccase production from Trametes versicolor

An efficient intermittent ultrasonic treatment strategy was developed to improve laccase production from Trametes versicolor mycelia cultures. The optimized strategy consisted of exposing 2-day-old mycelia cultures to 5-min ultrasonic treatments for two times with a 12-h interval at the fixed ultrasonic power and frequency (120 W, 40 kHz). After 5 days of culture, this strategy produced the highest extracellular laccase activity of 588.9 U/L among all treatments tested which was 1.8-fold greater than the control without ultrasound treatment. The ultrasonic treatment resulted in a higher pellet porosity that facilitated the mass transfer of nutrients and metabolites from the pellets to the surrounding liquid. Furthermore, the ultrasonic treatment induced the expression of the laccase gene (lcc), which correlated with a sharp increase in both extracellular and intracellular laccase activity. This is the first study to find positive effects of ultrasound on gene expression in fungal cells. These results provide a basis for understanding the stimulation of metabolite production and process intensification by ultrasonic treatment in filamentous fungal culture.

Laccase production by Trametes versicolor under limited-growth conditions using dyes as inducers

Laccase production by pre-growth pellets of Trametes versicolor using two types of textile dyes as inducers was studied. By decoupling the enzyme production phase from the growth phase, it is possible to reduce the time and nutrients required for laccase production. At the glucose maintenance level, the effect of the nitrogen source and textile dye was analysed using response surface methodology. Ammonium chloride was used as the inorganic nitrogen source. Two types of dyes were tested: Grey Lanaset G (GLG), a metal complex dye mixture containing nitrogen; and Alizarin Red (AR), an anthraquinonic dye with no nitrogen in its chemical structure. GLG induces laccase production at a higher extent than AR. Despite the limiting conditions required for the production of laccase, enzyme production increases with increasing ammonium chloride. When AR, the N-free dye, was used as an inducer, the optimal supply of N for laccase production was 1.2 mg/(g dry cell weight x d) as ammonium chloride. The reuse of fungal pellets in the repeated-batch mode under maintenance conditions was found to be a good strategy for improving laccase production, as enzyme production increased to up to seven times the production of the first cycle. It was demonstrated that GLG can be used as an inducer and as an N source and, thus, it is possible to decolorize the dye and to induce laccase production at the same time without adding an extra N source.

Effect of nitrogen and carbon sources on Indigo and Congo red decolourization by Aspergillus alliaceus strain 121C

The decolourizing ability of Aspergillus alliaceus 121C was investigated on solid medium. The effects of nitrogen (N), carbon (C) sources and supplements on the decolourization of Indigo and Congo red dyes were studied. It has been shown that both the nature and the quantity of available N- and C-sources exert an influence on growth and decolourization. For the six N-sources (NH(4)Cl, Diammonium Tartrate, urea, malt extract, peptone and yeast extract) tested for Congo red decolourization, 8mM yeast extract provided the higher decolourized zone diameter (80 mm) and colony diameter (80 mm). 12 mM urea provided the higher decolourized zone diameter (76+/-2mm) and colony diameter (80 mm) for Indigo decolourization. For the C-sources tested (glucose, starch, glycerol and lactose), above 12.5mM of glucose and 62.5mM of starch provided the higher decolourized zones diameters of 80 mm and 77+/-3mm for Indigo and Congo red, respectively. When the fungi was grown in liquid medium containing optimum carbon and nitrogen sources supplemented with oak sawdust and wheat bran, more than 98.6% and 98% of colour removal are obtained for Indigo and Congo red dyes, respectively. The detection of ligninolytic enzymes proved that laccase and lignine-peroxidase (LiP) are the two enzymes responsible of the decolourization of the two dyes.

Melanoidin-containing wastewaters induce selective laccase gene expression in the white-rot fungus Trametes sp. I-62

Wastewaters generated from the production of ethanol from sugar cane molasses may have detrimental effects on the environment due to their high chemical oxygen demand and dark brown color. The color is mainly associated with the presence of melanoidins, which are highly recalcitrant to biodegradation. We report here the induction of laccases by molasses wastewaters and molasses melanoidins in the basidiomycetous fungus Trametes sp. I-62. The time course of effluent decolorization and laccase activity in the culture supernatant of the fungus were correlated. The expression of laccase genes lcc1 and lcc2 increased as a result of the addition of complete molasses wastewater and its high molecular weight fraction to fungal cultures. This is the first time differential laccase gene expression has been reported to occur upon exposure of fungal cultures to molasses wastewaters and their melanoidins.