Bioethanol from oil palm empty fruit bunches as a second-generation bioethanol (bioethanol G2) has been developed. It produces high amounts of black liquor wastewater which also contains alkaline ...solution (NaOH). Black liquor wastewater is harmful to aquatic ecosystems if discharge directly into waters. This study aimed to determine decolorization of black liquor wastewater by using chemical and biological methods. Coagulation-flocculation method by using Poly Aluminium Chloride (PAC) and alumwith different ratio was also investigated. This study also identified the ability of white-rot fungi to decolorize black liquor wastewater on agar and liquid medium.The results showed that black liquor wastewater with initial concentration 30,000ppm can be decolorized by using two methods, coagulation-flocculation and decolorization by white-rot fungi.The optimum condition to obtain 96% decolorization was using concentration coagulant 1% combination alum-PAC 3:1 with total retention time 33minutes.Out of the three fungi studied, Trametes versicolor U97 showed the most degraded fungus onagar medium containing black liquor. In liquid medium, the percentage of decolorization ranged from 70% to 89% at 30 days depending on the fungal strain.
Emerging contaminants are a wide group of chemical products that are found at low concentrations in the environment. These contaminants can be either natural, e.g., estrogens, or synthetics, such as ...pesticides and pharmaceuticals, which can enter the environment through the water and sludge from wastewater treatment plants (WWTP). The growth of Trametes versicolor on membrane biological reactor (MBR) sludge in bioslurry systems at the Erlenmeyer scale was assessed and its capacity for removing pharmaceutical and personal care products (PPCPs) was evaluated. The ability of the fungus to remove hydrochlorothiazide (HZT) from liquid media cultures was initially assessed. Consequently, different bioslurry media (complete nutrient, glucose and no-nutrient addition) and conditions (sterile and non-sterile) were tested, and the removal of spiked HZT was monitored under each condition. The highest spiked HZT removal was assessed under non-sterile conditions without nutrient addition (93.2%). Finally, the removal assessment of a broad set of pharmaceuticals was performed in non-spiked bioslurry. Under non-sterile conditions, the fungus was able to completely degrade 12 out of the 28 drugs initially detected in the MBR sludge, achieving an overall degradation of 66.9%. Subsequent microbial analysis showed that the microbial diversity increased after 15 days of treatment, but there was still some T. versicolor in the bioslurry. Results showed that T. versicolor can be used to remove PPCPs in bioslurry systems under non-sterile conditions, without extra nutrients in the media, and in matrices as complex as an MBR sludge.
This paper describes electrochemical behavior of laccase from the fungus Trametes versicolor. The issues related to discrimination of the redox potentials corresponding to copper centers T1 and T2/T3 ...in the active site and possible mechanism of intramolecular electron transfer have been discussed. The electron‐transfer rate constant for laccase immobilized on carbon electrode is 3.4 s−1. The bioelectrocatalytic activity of the enzyme was studied in the presence of 1,4‐hydroquinone (HQ). The kinetics of HQ oxidation is very fast (KM=3.8 μM). However, the catalytic activity of laccase in the presence of high concentration of HQ decreases drastically. It is suggested that the T2/T3 copper center is able to accept electrons from HQ molecules directly via intramolecular channel.
•The transient kinetics of the laccase-catalyzed oxidation of aqueous phenol was modeled.•Phenol concentrations were in the micromolar to sub-micromolar range.•Inactivation of the enzyme during the ...oxidation reaction was insignificant.•The 4-parameter model was validated over wide ranges of phenol and enzyme concentrations.•The model could be simplified to a 3 parameter model with only minor loss in accuracy.
Oxidoreductase enzymes have the potential to be used to catalyze the oxidation of aromatic trace contaminants in wastewaters. The feasibility of this approach can be explored by modeling transient kinetics, particularly in the low substrate concentration range, where the model may be used to predict the quantity of enzyme and time required to achieve a particular level of conversion of a target compound. Laccase from Trametes versicolor was selected as a candidate enzyme due to its wide substrate specificity and its use of molecular oxygen as an oxidant. Phenol was selected as a target substrate. A four-parameter kinetic model was developed based on the known reactions of laccase. The model was applied to 30 sets of data collected from batch reactions conducted at pH 5 and 25°C over a three hour period. Initial phenol concentrations ranged from 0.5 to 50μM and applied enzyme concentrations ranged from 0.12 to 2.5μM. The model demonstrated its utility for predicting the quantities of enzyme and reaction times required to achieve desired levels of oxidation of phenol for varying initial concentrations. A three-parameter simplified version of the kinetic model was also developed to facilitate calibration and mathematical solution of its equations.
The lack of a commercially available robust and inexpensive laccase is a major barrier to the widespread application of this enzyme in various industrial sectors. By using an efficient system ...developed in Streptomyces lividans, we have produced by homologous expression 350 mg L⁻¹ of a bacterial laccase with a high purity and without any extensive purification. This is the highest production yield reported in the literature for a bacterial laccase. The secreted enzyme achieved oxidation under a wide pH range depending on the substrate: 4.0 for 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) and 9.0 for 2,6-dimethoxyphenol. Furthermore, this bacterial laccase was found to be quite resistant under various conditions. It withstands pH from 3.0 to 9.0, shows a great thermostability at 70°C and was highly resistant toward conventional inhibitors. For instance, while the laccase of Trametes versicolor was completely inhibited by 1 mM NaN₃, the laccase of Streptomyces coelicolor was fully active under the same conditions. To assess application potential of this laccase, we have investigated its ability to decolourise Indigo carmine. This enzyme was able to rapidly decolourise the dye in the presence of syringaldehyde as a redox mediator.
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► Enzymatic membranes prepared by grafting laccases onto ceramic supports. ► Phenolic compounds depletion from aqueous solutions by enzymatic membrane. ► Membrane plugging phenomena ...by polymers formed from phenols degradation. ► Enzymatic membranes well adapted for low reactive phenols compounds depletion.
This work describes the optimization and characterization of enzymatic membranes assessed for the degradation of two phenolic compounds (2,6-dimethoxyphenol (DMP) and guaiacol) by laccases from Trametes versicolor using the “flow-through membrane reactor” concept. The results obtained show that the optimized membrane is very reactive, although polymer formation during DMP degradation causes membrane plugging that subsequently decreases permeate flow. Nevertheless, the enzymatic membrane can be of interest for much diluted substrates or for relatively un-reactive reaction intermediates that do not cause significant membrane plugging by polymer formation. This work opens new perspectives for the application of enzymatic membranes for the removal of refractory pollutants containing phenolic groups.
The incidence and mortality of colorectal cancer have shown an upward trend in the past decade. Therefore, the prevention, diagnosis, and treatment of colorectal cancer still need our continuous ...attention. Finding compounds with strong anticancer activity and low toxicity is a good strategy for colorectal cancer (CRC) therapy. Trametes versicolor is a traditional Chinese medicinal mushroom with a long history of being used to regulate immunity and prevent cancer. Its extractions were demonstrated with strong cell growth inhibitory activity on human colorectal tumor cells, while the anticancer activity of them is not acted through a direct cytotoxic effect. However, the intricacy and high molecular weight make mechanistic research difficult, which restricts their further application as a medication in clinical cancer treatment. Recent research has discovered a small molecule polysaccharide peptide derived from Trametes versicolor that has a distinct structure after decades of Trametes versicolor investigation. Uncertain molecular weight and a complex composition are problems that have been solved through studies on its structure, and it was demonstrated to have strong anti-proliferation activity on colorectal cancer in vitro and in vivo via interaction with EGFR signaling pathway. It opens up new horizons for research in this field, and these low molecular weight polysaccharide peptides provide a new insight of regulation of colorectal cancer proliferation and have great potential as drugs in the treatment of colorectal cancer.
Solid-state fermentation requires the development of more efficient cultivation systems for its industrial application. The objective of this work was to evaluate the effect of aeration regime on the ...production of biomass and several lignocellulolytic enzymes (laccase, manganese peroxidase, endoxylanase, β-glucosidase, and total cellulases) by Trametes versicolor in a novel fixed-bed solid-state pilot-scale bioreactor. Three regimes were assessed: natural convection, low aeration level (10 min every 6 h at 10 L/h air flowrate), and high aeration level (1 h every 6 h at 10 L/h air flowrate). The mushroom was grown on a medium based on lignocellulosic residues. The design of the bioreactor, as well as the control of aeration, humidity, and temperature of the beds, allowed T. versicolor to grow properly on the medium, reaching a maximum biomass production of 204.7 mg/g dry solid (ds). The influence that aeration regime had on the production of lignocellulolytic enzymes was determined. Low level of forced aeration favored obtaining the highest titers of laccase (6.37 U/g ds) compared to natural convection and high aeration level. The greatest lignin degradation was also verified for low aeration regime. For the first time, pilot scale cultivation of T. versicolor was reported in a fixed-bed bioreactor.
The natural durability of wood is linked to its chemical composition and in particular the presence of metabolites called extractives that often possess chemical reactivity. For dealing with these ...compounds, wood degraders have developed detoxification systems usually involving enzyme families. Among these enzymes, glutathione transferases (GSTs) are involved in the decrease of the reactivity of toxic compounds. In this study, the hypothesis that the detoxification systems of wood decaying fungi could be indicators of the chemical reactivity of wood extracts has been tested. This approach has been evaluated using 32 wood extracts coming from French Guiana species, testing their antimicrobial ability, antioxidative properties, and reactivity against six GSTs from the white rot Trametes versicolor. From the obtained data, a significant correlation between the antimicrobial and antioxidative properties of the tested wood extracts and GST interactions was established. In addition, the chemical analysis performed on one of the most reactive extracts (an acetonic extract of Bagassa guianensis) has demonstrated oxyresveratrol as a major constituent. We were able to cocrystallize one GST with this commercially interesting compound. Taken together, the presented data support the hypothesis that detoxifying enzymes could be used to identify the presence of molecules of industrial interest in wood extracts.
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