Paraconiothyrium Variabile Research Articles

Ability of marine-derived fungi isolated from polluted saline environment for enzymatic hydrocarbon remediation.

Marine-derived fungi have attracted much attention due to their ability to present a new biosynthetic diversity. About 50 fungal isolates were obtained from Tunisian Mediterranean seawater and then screened for the presence of lignin-peroxidase (LiP), manganese-dependent peroxidase (MnP), and laccase (Lac) activities. The results obtained from both qualitative and quantitative assays showed that four of marine fungi isolates had a high potential to produce lignin-degrading enzymes. They were characterized taxonomically by a molecular method, based on international spacer (ITS) rDNA sequence analysis, as Chaetomium jodhpurense (MH667651.1), Chaetomium maderasense (MH665977.1), Paraconiothyrium variabile (MH667653.1), and Phoma betae (MH667655.1) which have been reported as producers of ligninolytic enzyme in the literature.The enzymatic activities and culture conditions were optimized using a Fractional Factorial design (2 7- 4). Then, fungal strains were incubated with the addition of 1% of crude oil in 50% of seawater for 25days to evaluate their abilities to simultaneously degrade hydrocarbon compounds and to produce ligninolytic enzymes. The strain P. variabile exhibited the highest crude oil degradation rate (48.3%). Significant production of ligninolytic enzymes was recorded during the degradation process, which reached 2730 U/L for the MnP, 410 U/L for LiP, and 168.5 U/L for Lac. The FTIR and GC-MS analysis confirmed that the isolates rapidly biodegrade crude oil under ecological and economic conditions.

Simultaneous Heavy Metal-Polycyclic Aromatic Hydrocarbon Removal by Native Tunisian Fungal Species.

Multi-contamination by organic pollutants and toxic metals is common in anthropogenic and industrial environments. In this study, the five fungal strains Chaetomium jodhpurense (MH667651.1), Chaetomium maderasense (MH665977.1), Paraconiothyrium variabile (MH667653.1), Emmia lacerata, and Phoma betae (MH667655.1), previously isolated in Tunisia, were investigated for the simultaneous removal and detoxification of phenanthrene (PHE) and benzo[a]anthracene (BAA), as well as heavy metals (HMs) (Cu, Zn, Pb and Ag) in Kirk's media. The removal was analysed using HPLC, ultra-high performance liquid chromatography (UHPLC) coupled to a QToF mass spectrometer, transmission electron microscopy, and toxicology was assessed using phytotoxicity (Lepidium sativum seeds) and Microtox® (Allivibrio fisherii) assays. The PHE and BAA degradation rates, in free HMs cultures, reached 78.8% and 70.7%, respectively. However, the addition of HMs considerably affected the BAA degradation rate. The highest degradation rates were associated with the significant production of manganese-peroxidase, lignin peroxidase, and unspecific peroxygenase. The Zn and Cu removal efficacy was considerably higher with live cells than dead cells. Transmission electron microscopy confirmed the involvement of both bioaccumulation and biosorption processes in fungal HM removal. The environmental toxicological assays proved that simultaneous PAH and HM removal was accompanied by detoxification. The metabolites produced during co-treatment were not toxic for plant tissues, and the acute toxicity was reduced. The obtained results indicate that the tested fungi can be applied in the remediation of sites simultaneously contaminated with PAHs and HMs.

Molecular crosstalk between the endophyte Paraconiothyrium variabile and the phytopathogen Fusarium oxysporum – Modulation of lipoxygenase activity and beauvericin production during the interaction

Plants comprise many asymptomatic fungal endophytes with potential roles of plant protection against abiotic and biotic stresses. Endophytes communicate with their host plant, with other endophytes and with invading pathogens but their language remains largely unknown. This work aims at understanding the chemical communication and physiological interactions between the fungal endophyte Paraconiothyrium variabile and the phytopathogen Fusarium oxysporum. Oxylipins, common means of communication, such as 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE), had been shown in our earlier studies to be overproduced during dual culture between the two fungal antagonists. On the other hand, the mycotoxin beauvericin was reduced in the interaction zone. The present work addresses the mechanisms underlying these changes. Hydroperoxy oxylipins are produced by lipoxygenases and P. variabile contains two lipoxygenase genes (pvlox1 and pvlox2), whereas pvlox2, but not pvlox1, is specifically up regulated during the interaction and none of the F. oxysporum lox genes vary. Heterologous expression of pvlox2 in yeast shows that the corresponding enzyme PVLOX2 produces 13-HPODE and, therefore, is most likely at the origin of the overproduced 13-HPODE during the interaction. Compellingly, beauvericin synthase gene beas expression is induced and beauvericin amounts increase in F. oxysporum mycelium when in contact with P. variabile. 13-HPODE, however, does not affect beas gene expression. Beauvericin, indeed, inhibits P. variabile growth, which counteracts and biotransforms the mycotoxin leading to reduced amounts in the interaction zone which allows further expansion of the endophyte. In order to study the interaction between the protagonists in planta, we set up an in vitro tripartite interaction assay, including the model plant Arabidopsis thaliana. F. oxysporum rapidly kills A. thaliana plants, whereas P. variabile provides up to 85% reduction of plant death if present before pathogen attack. Future studies will shed light on the protection mechanisms and the role of oxylipins and beauvericin degradation herein with the long-term aim of using endophytes in plant protection.

An Integrative Approach to Decipher the Chemical Antagonism between the Competing Endophytes Paraconiothyrium variabile and Bacillus subtilis.

An integrative approach combining traditional natural products chemistry, molecular networking, and mass spectrometry imaging has been undertaken to decipher the molecular dialogue between the fungus Paraconiothyrium variabile and the bacterium Bacillus subtilis, which were isolated as endophytes from the conifer Cephalotaxus harringtonia and are characterized by a strong and mutual antibiosis. From this study, we highlight that bacterial surfactins and a fungal tetronic acid are involved in such competition and that the fungus is able to hydrolyze surfactins to fight against the bacterial partner.

A Reactive Eremophilane and Its Antibacterial 2(1H)-Naphthalenone Rearrangement Product, Witnesses of a Microbial Chemical Warfare.

Two sesquiterpenes, 4-epi-microsphaeropsisin (1) and a dihydrofurano-2(1H)-naphthalenone (variabilone, 2) which represents a new skeleton, were isolated from endophytic fungus Paraconiothyrium variabile. Reactivity studies showed that eremophilane 1 is a precursor of 2 through acid-promoted methyl 1,2-migration and aromatization. An electrophilic intermediate of this transformation was intercepted by N-acetylcysteamine, a biomimetic nucleophile. Only compound 2 was antibacterial against endophytic bacterium Bacillus subtilis (coisolated with P. variabile), suggesting a role in the microbial competition in plants.

Studies on the laccase-mediated decolorization, kinetic, and microtoxicity of some synthetic azo dyes

BackgroundEnzymatic elimination of synthetic dyes, one of the most environmentally hazardous chemicals, has gained a great interest during the two last decades. The present study was performed to evaluate the decolorization and detoxification potential of the purified laccase of Paraconiothyrium variabile in both non-assisted and hydroxybenzotriazole-aided form against six azo dyes.ResultsThe obtained results showed that Acid Orange 67, Disperse Yellow 79, Basic Yellow 28, Basic Red 18, Direct Yellow 107, and Direct Black 166 were decolorized up to 65.3, 53.3, 46.7, 40.7, 34, and 26.2 %, respectively, after 1 h treatment with laccase (0.5 U/mL). Addition of HBT up to 5 mM enhanced decolorization percent of all the investigated dyes. The results of kinetic study introduced the monoazo dye of Acid Orange 67 as the most suitable substrate for laccase with Km of 0.49 mM and Vmax of 189 mmol/min/mg. Evaluation the toxic effect of laccase-treated dye sample based on the growth inhibition of standard bacterial strains revealed decrease in toxicity of all applied dyes after treatment by laccase.ConclusionsApplication of the P. variabile laccase as biocatalyst efficiently decreased the toxicity of all studied synthetic azo dyes.

Environmental stress and elicitors enhance taxol production by endophytic strains of Paraconiothyrium variabile and Epicoccum nigrum.

This study examined the effect of different elicitors (seven, different concentrations) and environmental factors (water activity (aw), pH) on taxol production by strains of two endophytic fungi, Paraconiothyrium variabile and Epicoccum nigrum, isolated from temperate yew trees. A defined liquid broth medium was modified with elicitors, solute aw depressors at different pH values. For P. variabile, the best elicitor was salicylic acid at 50mg/l which gave a taxol yield of 14.7±4.8μg/l. The study of synergistic effects between elicitor, aw and pH on taxol production showed that the highest yield of taxol (68.9±11.9μg/l) was produced under modified ionic stress of 0.98aw (KCl) at pH 5 when supplemented with 20mg/l of salicylic acid. For E. nigrum, serine was the best elicitor which increased yield significantly (29.6 fold) when KCL was used as the aw depressor (0.98aw) at pH 5.0 with 30mg/l of serine. The maximum taxol yield produced by E. nigrum was 57.1±11.8μg/l. Surface response models were used to build contour maps to determine the conditions for maximum and marginal conditions for taxol yield in relation to the best elicitor and aw, and the best pH for the first time. This will be beneficial for identifying key parameters for improvement of taxol yields by endophytic fungi.

Isolation, identification, and ecology of growth and taxol production by an endophytic strain of Paraconiothyrium variabile from English yew trees (Taxus baccata)

Endophytic fungi were isolated/screened from temperate Taxus baccata (Yew) for production of the anti-cancer drug taxol. Of 242 endophytic fungi isolated from surface-sterilised Yew tree twig segments, only two produced taxol in a defined liquid medium; confirmed by HPLC and LC-MS/MS analyses. They were identified by molecular means by sequencing of ITS1/ITS2 regions and shown to be Paraconiothyrium variabile and Epicoccum nigrum. They produced 1.75 and 1.32 μgL−1 taxol respectively in a defined medium. Studies focussed on the P. variabile strain as it produced higher taxol amounts. Solute type (NaCl, KCl, Glucose, Glycerol, sorbitol), temperature (20, 25 and 30 oC) and water availability (water activity, aw; 0.90–0.99) on growth and taxol production by P. variabile was determined. Growth was similar on media with different solutes (1.0–1.25 mm d−1), optimum at 0.99 aw and 25 oC. In contrast, optimum taxol production was in a defined medium modified with KCl, at 0.98 aw and 20/25 oC, with approx. 2.3 and 7 μgL−1 respectively. No taxol was produced at <0.96 aw, at 25–30 oC, and <0.94 aw at 20 oC. This suggests that taxol producing endophytic fungi are in English yew trees and may have potential for utilisation as cell factories for production of this pharmaceutically useful compound.

Paraconiothyrium variabile, an ascomycete endophyte, suppresses mycotoxin production in the plant pathogen Fusarium oxysporum

Fungal plant pathogens produce more than 70% of all major crop diseases and destroy 15% of global agricultural production through yield losses and mycotoxin contamination, making them by far the most harmful class of plant pathogens. Fusarium is a cosmopolitan genus of filamentous ascomycete fungi that includes many toxin-producing plant pathogens of agricultural importance [1]. Mycotoxin contamination of agricultural products makes them unsuitable for food or feed. As phytopathogens, fusaria employ a broad range of infection strategies and host specificity varies among Fusarium species. The ubiquitous soil-borne F. oxysporum causes vascular wilt disease in over 100 different plant species and it is also an emerging pathogen of humans that can cause invasive infections in immunocompromised patients [2]. Research in our laboratory focuses on secondary metabolites produced by endophytic fungi, which live in plants without provoking disease symptoms. We showed that the endophyte Paraconiothyrium variabile, when co-cultured with F. oxysporum, has an antagonistic growth effect on the phytopathogen and actively suppresses the production of beauvericin, a mycotoxin of F. oxysporum involved in virulence [3]. Our study also showed that the oxylipin 13-oxo-9,11-octadecadienoic acid (13-oxo-ODE) is overproduced during this antagonistic interaction and is responsible for over 50% of beauvericin suppression. The genome sequencing of the endophyte P. variabile is in progress and we have already established a genetic transformation system in this fungus. Using molecular approaches, we are currently trying to elucidate the biosynthesis of the 13-oxo-ODE oxylipin in P. variabile and its mode of action on beauvericin regulation in F. oxysporum.

Efficient decolorization and detoxification of reactive orange 7 using laccase isolated from Paraconiothyrium variabile, kinetics and energetics

The fungal laccase isolated from Paraconiothyrium variabile was applied to optimize the enzymatic decolorization and detoxification of the azo dye reactive orange 7 using response surface methodology. Initial screening using fractional factorial design was carried out to select important independent variables that significantly affect the yield of decolorization including enzyme activity, pH, and incubation time. Optimum condition for maximal dye decolorization obtained by central composite design and surface plots were laccase activity 1.25 U/mL, pH 6.0, and incubation time 12.5 min. In addition, the kinetic and energetic parameters for enzymatic decolorization of reactive orange 7 were studied and the calculated values for Km, Vmax, Ea, ΔH, and ΔS were 1.14 mM, 283.28 mM/min.mg, 40 kJ/mol, 89 kJ/mol, and 285 J/mol.K, respectively. Decolorization is endothermic and spontaneous at temperatures higher than 37.8 °C. Microtoxicity evaluation demonstrated a decrease in toxicity of the laccase-treated dye in comparison with the parent dye.

Laccase-catalyzed decolorization and detoxification of Acid Blue 92: statistical optimization, microtoxicity, kinetics, and energetics.

BackgroundIn recent years, enzymatic-assisted removal of hazardous dyes has been considered as an alternative and eco-friendly method compared to those of physicochemical techniques. The present study was designed in order to obtain the optimal condition for laccase-mediated (purified from the ascomycete Paraconiothyrium variabile) decolorization of Acid Blue 92; a monoazo dye, using response surface methodology (RSM). So, a D-optimal design with three variables, including pH, enzyme activity, and dye concentration, was applied to optimize the decolorization process. In addition, the kinetic and energetic parameters of the above mentioned enzymatic removal of Acid Blue 92 was investigated.ResultsDecolorization of Acid Blue 92 was maximally (94.1% ± 2.61) occurred at pH 8.0, laccase activity of 2.5 U/mL, and dye concentration of 75 mg/mL. The obtained results of kinetic and energetic studies introduced the laccase-catalyzed decolorization of Acid Blue 92 as an endothermic reaction (Ea, 39 kJ/mol; ΔS, 131 J/mol K; and ΔH, 40 kJ/mol) with Km and Vmax values of 0.48 mM and 227 mM/min mg, respectively. Furthermore, the results of microtoxicity study revealed that the toxicity of laccase-treated dye was significantly reduced compared to the untreated dye.ConclusionsTo sum up, the present investigation introduced the Paraconiothyrium variabile laccase as an efficient biocatalyst for decolorization of synthetic dye Acid Blue 92.

A new amperometric biosensor based on Fe3O4/polyaniline/laccase/chitosan biocomposite-modified carbon paste electrode for determination of catechol in tea leaves.

In the present study, a new biosensor based on laccase from Paraconiothyrium variabile was developed for catechol. The purified enzyme entrapped into the Fe3O4/polyaniline/chitosan (Fe3O4/polyaniline (PANI)/chitosan (CS)) biocomposite matrix film without the aid of other cross-linking reagents by a one-step electrodeposition on the surface of carbon paste electrode (CPE). The formed layer of biocomposite was characterized with scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The biosensor was optimized with respect to biocomposite composition, enzyme loading, and solution pH by amperometry method. The biosensor exhibited noticeable eletrocatalytic ability toward catechol with a linear concentration range from 0.5 to 80 μM and a detection limit of 0.4 μM. The biosensor showed optimum response within 8 s, at pH 5, and 40 °C. The apparent Michaelis-Menten (K M (app)) was found to be 1.092 μM. The fabricated biosensor could be applied for determination of catechol in tea leaf samples.

The fungal leaf endophyte Paraconiothyrium variabile specifically metabolizes the host-plant metabolome for its own benefit

Fungal endophytes live inside plant tissues and some have been found to provide benefits to their host. Nevertheless, their ecological impact is not adequately understood. Considering the fact that endophytes are continuously interacting with their hosts, it is conceivable that both partners have substantial influence on each other’s metabolic processes. In this context, we have investigated the action of the endophytic fungus Paraconiothyrium variabile, isolated from the leaves of Cephalotaxus harringtonia, on the secondary metabolome of the host-plant. The alteration of the leaf compounds by the fungus was monitored through metabolomic approaches followed by structural characterization of the altered products. Out of more than a thousand molecules present in the crude extract of the plant leaf, we have observed a specific biotransformation of glycosylated flavonoids by the endophyte. In all cases it led to the production of the corresponding aglycone via deglycosylation. The deglycosylated flavonoids turned out to display significant beneficial effects on the hyphal growth of germinated spores. Our finding, along with the known allelopathic role of flavonoids, illustrates the chemical cooperation underlying the mutualistic relationship between the plant and the endophyte.

Removal of phenol and bisphenol-A catalyzed by laccase in aqueous solution.

BackgroundElimination of hazardous phenolic compounds using laccases has gained attention during recent decades. The present study was designed to evaluate the ability of the purified laccase from Paraconiothyrium variabile (PvL) for elimination of phenol and the endocrine disrupting chemical bisphenol A. Effect of laccase activity, pH, and temperature on the enzymatic removal of the mentioned pollutants were also investigated.ResultsAfter 30 min treatment of the applied phenolic pollutants in the presence of PvL (5 U/mL), 80% of phenol and 59.7% of bisphenol A was removed. Increasing of laccase activity enhanced the removal percentage of both pollutants. The acidic pH of 5 was found to be the best pH for elimination of both phenol and bisphenol A. Increasing of reaction temperature up to 50°C enhanced the removal percentage of phenol and bisphenol A to 96.3% and 88.3%, respectively.ConclusionsTo sum up, the present work introduced the purified laccase of P. variabile as an efficient biocatalyst for removal of one of the most hazardous endocrine disruptor bisphenol A.

Decolorization of two synthetic dyes using the purified laccase of Paraconiothyrium variabile immobilized on porous silica beads

BackgroundDecolorization of hazardous synthetic dyes using laccases in both free and immobilized form has gained attention during the last decades. The present study was designed to prepare immobilized laccase (purified from Paraconiothyrium variabile) on porous silica beads followed by evaluation of both free and immobilized laccases for decolorization of two synthetic dyes of Acid Blue 25 and Acid Orange 7. Effects of laccase concentration, pH and temperature alteration, and presence of 1-hydroxybenzotriazole (HBT) as laccase mediator on decolorization pattern were also studied. In addition, the kinetic parameters (K m and V max ) of the free and immobilized laccases for each synthetic dye were calculated.ResultsImmobilized laccase represented higher temperature and pH stability compare to free one. 39% and 35% of Acid Blue 25 and Acid Orange 7 was decolorized, respectively after 65 min incubation in presence of the free laccase. In the case of immobilized laccase decolorization percent was found to be 76% and 64% for Acid Blue 25 and Acid Orange 7, respectively at the same time. Increasing of laccase activity enhanced decolorization percent using free and immobilized laccases. Relative decolorization of both applied dyes was increased after treatment by laccase-HBT system. After nine cycles of decolorization by immobilized laccase, 26% and 31% of relative activity were lost in the case of Acid Blue 25 and Acid Orange 7, respectively.ConclusionsTo sum up, the present investigation introduced the immobilized laccase of P. variabile on porous beads as an efficient biocatalyst for decolorization of synthetic dyes.

First Report of Leaf Spot of Phoenix theophrasti Caused by Paraconiothyrium variabile in Greece.

In the spring of 2011, a severe leaf spot disease of Phoenix theophrasti was observed in the vicinity of Heraklion (Crete), Greece. Initial symptoms were small, round-ovoid spots of varying shades of brown on the leaves, later being transformed into oblong streaks (average dimensions 7.3 ± 1.0 × 3.3 ± 0.5 mm), surrounded by dark brown rings. As the disease progressed, the expanding streaks often coalesced to form enlarged necrotic lesions. Similar symptoms were also detected on petioles and leaf bases. Extended spotting and blighting occasionally resulted in leaf death. A filamentous fungus was consistently isolated onto potato dextrose agar plates from the periphery of the characteristic lesions, with cultures invariably producing brick to cinnamon colonies with sparse aerial mycelium, subglobose and dark brown superficial pycnidial conidiomata on pine needles, 1- to 3-celled hyaline conidiophores, and hyaline, subcylindrical to ellipsoidal, 1-celled, smooth- and thin-walled conidia, with average dimensions of 3.5 ± 0.6 × 1.7 ± 0.4 μm (n = 100). Total DNA of two isolates was extracted and used for PCR amplification and sequencing of the ITS1-5.8S-ITS2 region, together with parts of the flanking 18S and 28S rRNA genes (4). Both sequences (GenBank Accession Nos. JX456476 and JX456477) were 100% identical to deposited Paraconiothyrium variabile ITS sequences (EU295640 to 48, JN983440 and 41, and JF934920), and were clustered together as a single group with these sequences with good support by phylogenetic analysis that included representatives of the relative P. brasiliense and P. africanum species. Based on the morphological, molecular, and phylogenetic analyses, the pathogen was identified as P. variabile Riccioni, Damm, Verkley & Crous (2). To prove pathogenicity, 10 P. theophrasti 2-year-old seedlings were sprayed with a conidial suspension of the fungus (107 conidia ml-1, 10 ml per plant), while five additional control plants were treated with sterile distilled water. All plants were maintained in the greenhouse at 15 ± 5°C, with 90% humidity. Characteristic leaf spots were evident 4 weeks post inoculation on the older leaves, and P. variabile was consistently reisolated from all inoculated plants. No symptoms were observed on control plants. Paraconiothyrium variabile has been isolated from various woody host plants such as Prunus persica, P. salicina, and Malus sp. in South Africa (1,2), Actinidia chinensis and A. deliciosa in Italy (2), Laurus nobilis in Turkey (2), and Salix matsudana in China (3). To our knowledge, this is the first report of P. variabile naturally infecting and causing a leaf spot disease on a palm species. Palms are extensively used as ornamentals throughout Greece and the occurrence of P. variabile can potentially result in economic loss to the local ornamental industry.

The enzymatic decolorization and detoxification of synthetic dyes by the laccase from a soil-isolated ascomycete, Paraconiothyrium variabile

The enzymatic decolorization of 13 synthetic dyes with azo- and anthraquinone-based chemical structures using the purified laccase from Paraconiothyrium variabile was assessed in the presence and absence of 1-hydroxybenzotriazole (HBT) as a laccase mediator. The highest decolorization percentage was found for Acid Red 18 (97%) followed by Direct Red 81 (68.3%), Reactive Yellow 15 (60.2%), and Disperse Blue 56 (58%) after 15 min of incubation in the presence of 0.1 U mL−1 of the enzyme. The use of the laccase-HBT system increased decolorization percentage of Reactive Orange 16, Reactive Black 5, Direct Blue 71, Disperse Red 177, and Acid Yellow 36, while other chemical dyes were not affected by an increase of the HBT concentration. The kinetic parameters of the purified laccase for each textile dye were also calculated. A microtoxicity study with respect to the inhibition of bacterial growth showed a decrease in toxicity of the laccase-treated dye solution.

Evaluation of fungus-induced agilawood from Aquilaria sinensis in China

Agilawood is a rare and valuable traditional medicine used worldwide since ancient times. However, its formation in the tree Aquilaria sinensis under natural conditions takes a long time. Fungi with high levels of bioactivity for triggering agilawood formation could enable the establishment of plantations of A. sinensis for improved production of this traditional medicine in Hainan Province, China. The objective of the present study was to evaluate the chemical components of agilawood induced in A. sinensis by inoculation with the fungus Paraconiothyrium variabile. The results using by GC-MS and HPLC indicated that sesquiterpenoids, chromones and their analogues were produced when the fungus was inoculated for 8 months into the host tree. Dibutyl phthalate and Phenol,2,2′-methylenebis[6-(1,1-dimethylethyl)- 4-methyl]-, the main components of A. sinensis, wood were converted into components of agilawood. The data showed that the fungus-induced agilawood samples were similar to natural agilawood and could be used as an agilawood substitute. This is the first time that agilawood formation has been shown to result from inoculation of A. sinensis with the bioactive fungus P. variabile.

One-step enantioselective synthesis of (4S)-isosclerone through biotranformation of juglone by an endophytic fungus

We describe here a direct access to (4S)-isosclerone (+)-1, an important structural component of several natural products featuring a spirobisnaphthalene ring system. Starting with the commercially available 5-hydroxy-1,4-naphthalenedione (juglone), biotransformation by the isosclerone-producing endophytic fungus Paraconiothyrium variabile is described. The absolute configuration of (+)-1 was determined unambiguously using circular dichroism and by measurement of the optical rotation. Moreover, the biotransformations of other naphthalene derivatives were undertaken and led to the corresponding (4S)-hydroxy-1-tetralone. At last, this work brings some insights on the biosynthesis of natural tetralones.

Synthetic dye decolorization by three sources of fungal laccase

Decolorization of six synthetic dyes using three sources of fungal laccase with the origin of Aspergillus oryzae, Trametes versicolor, and Paraconiothyrium variabile was investigated. Among them, the enzyme from P. variabile was the most efficient which decolorized bromophenol blue (100%), commassie brilliant blue (91%), panseu-S (56%), Rimazol brilliant blue R (RBBR; 47%), Congo red (18.5%), and methylene blue (21.3%) after 3 h incubation in presence of hydroxybenzotriazole (HBT; 5 mM) as the laccase mediator. It was also observed that decolorization efficiency of all dyes was enhanced by increasing of HBT concentration from 0.1 mM to 5 mM. Laccase from A. oryzae was able to remove 53% of methylene blue and 26% of RBBR after 30 min incubation in absence of HBT, but the enzyme could not efficiently decolorize other dyes even in presence of 5 mM of HBT. In the case of laccase from T. versicolor, only RBBR was decolorized (93%) in absence of HBT after 3 h incubation.