Characterization of Penicillium crustosum L-asparaginase and its acrylamide alleviation efficiency in roasted coffee beans at non-cytotoxic levels.

This work aims at isolating a fungal source for L-asparaginase production to be applied in reducing acrylamide levels in coffee beans at non-cytotoxic levels. An L-asparaginase-producing fungus was isolated from an agricultural soil sample and identified as Penicillium crustosum NMKA 511. A maximum L-asparaginase activity of 19.10 U/mL was obtained by the above-mentioned fungus when grown under optimum conditions (i.e. 16.96 g/L sucrose as carbon source, 1.92 g/L peptone as nitrogen source, pH 7.7 and 33.5 °C). Further, the produced L-asparaginase was purified and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that P. crustosum L-asparaginase was a heterodimer enzyme with molecular weights of approximately 41.3 and 44.4 kDa. Also, the purified P. crustosum L-asparaginase was specific towards L-asparagine and showed negligible and no effects towards L-glutamine and D-asparagine, respectively. Additionally, the purified L-asparaginase reduced the acrylamide levels by 80.7% and 75.8% in light and dark roasted coffee beans, respectively. The amount of L-asparaginase used to reduce acrylamide was considered safe when cell viability reached 94.6%.

Enzymatic potential for the valorization of agro-industrial by-products.

Agro-industrial residues and by-products are a crescent environmental problem since they are often discarded without proper treatment, and still have growing production. These residues are rich from a nutritional point of view and contain various industrial relevant compounds, such as phenolic compounds, fibers, vitamins, sugars and others. The crescent worrying about environmental issues has led researchers and industries to focus on "eco-friendly" solutions for everyday problems. In this sense, the use of enzymes for the valorization of agro-industrial residues is a safe and green alternative technology. Hence, this review aims to show the enzyme potential for the use and valorization of several agro-industrial residues, focusing on the most produced residues worldwide, such as fruits, grains and lignocellulosic residues, as well as a brief explanation of microbial enzymes, its production and optimization, altogether with tools to identify producing microorganisms.

Reversible covalent immobilization of Trametes villosa laccase onto thiolsulfinate-agarose: An insoluble biocatalyst with potential for decoloring recalcitrant dyes.

The development of a solid-phase biocatalyst based on the reversible covalent immobilization of laccase onto thiol-reactive supports (thiolsulfinate-agarose [TSI-agarose]) was performed. To achieve this goal, laccase-producing strains isolated from Eucalyptus globulus were screened and white rot fungus Trametes villosa was selected as the best strain for enzyme production. Reduction of disulfide bonds and introduction of "de novo" thiol groups in partially purified laccase were assessed to perform its reversible covalent immobilization onto thiol-reactive supports (TSI-agarose). Only the thiolation process dramatically improved the immobilization yield, from 0% for the native and reduced enzyme to 60% for the thiolated enzyme. Mild conditions for the immobilization process (pH 7.5 and 4°C) allowed the achievement of nearly 100% of coupling efficiency when low loads were applied. The kinetic parameters, pH, and thermal stabilities for the immobilized biocatalyst were similar to those for the native enzyme. After the first use and three consecutives reuses, the insoluble derivative kept more than 80% of its initial capacity for decolorizing Remazol Brilliant Blue R, showing its suitability for color removal from textile industrial effluents. The possibility of reusing the support was demonstrated by the reversibility of enzyme-support binding.

Immobilized-laccase bioreactors for wastewater treatment.

Laccases have shown to be efficient biocatalysts for the removal of recalcitrant pollutants from wastewater. Thus, they catalyze the oxidation of a wide variety of organic compounds by reducing molecular oxygen to water. However, the use of free laccases holds several drawbacks such as poor reusability, high cost, low stability and sensitivity to different denaturing agents that may occur in wastewater. Such drawbacks can be circumvented by immobilizing laccase enzymes in/on solid carriers. Hence, during the last decades different approaches considering various techniques and solid carriers to immobilize laccase enzymes have been developed and tested for the removal of pollutants from wastewater. To scale up wastewater treatment bioprocesses, immobilized laccases are placed in different reactor configurations.

Biologically active secondary metabolites from white-rot fungi.

In recent years, there has been a considerable rise in the production of novel metabolites derived from fungi compared to the ones originating from bacteria. These organic substances are utilized in various sectors such as farming, healthcare, and pharmaceutical. Since all dividing living cells contain primary metabolites, secondary metabolites are synthesized by utilizing intermediate compounds or by-products generated from the primary metabolic pathways. Secondary metabolites are not critical for the growth and development of an organism; however, they exhibit a variety of distinct biological characteristics. White-rot fungi are the only microorganisms able to decompose all wood components. Hence, they play an important role in both the carbon and nitrogen cycles by decomposing non-living organic substrates. They are ubiquitous in nature, particularly in hardwood (e.g., birch and aspen) forests. White-rot fungi, besides ligninolytic enzymes, produce different bioactive substances during their secondary metabolism including some compounds with antimicrobial and anticancer properties. Such properties could be of potential interest for the pharmaceutical industries. Considering the importance of the untapped biologically active secondary metabolites from white-rot fungi, the present paper reviews the secondary metabolites produced by white-rot fungi with different interesting bioactivities.

Decolorization of the metal textile dye Lanaset Grey G by immobilized white-rot fungi.

In this paper we studied the ability of four Tunisian-isolated fungi (i.e. Coriolopsis gallica, Bjerkandera adusta, Trametes versicolor and Trametes trogii) immobilized into Ca-alginate beads to decolorize the metal textile dye Lanaset Grey G (LG). The effect of different operational conditions, such as initial dye concentration, temperature, pH, beads/medium ratio and agitation, on dye decolorization by the immobilized fungi was investigated. Maximal decolorization percentages of 88.7%, 89.3%, 82.1% and 81.3% for C. gallica, B. adusta, T. versicolor and T. trogii were attained, respectively, when operating at an initial LG concentration of 150 mg/L, pH values of 5.0-6.0, temperatures of 40-45 °C and a beads/medium ratio of 20% (w/v) in static conditions after 72 h of incubation. Subsequently, the re-usability of the immobilized fungi was evaluated. After three decolorization cycles, the decolorization percentage of free cell cultures dropped to values below 36%, while decolorization percentages of about 75%, 70%, 60% and 68% were obtained by the immobilized cultures of C. gallica, B. adusta, T. versicolor and T. trogii, respectively.

The Determination of Assay for Laccase of Bacillus subtilis WPI with Two Classes of Chemical Compounds as Substrates.

Ligninolytic enzyme complexes are involved in lignin degradation. Among them laccases are outstanding because they use molecular oxygen as a co-substrate instead of hydrogen peroxide as used by peroxidases. Bacterial laccase of Bacillus genus was first reported in Claus and Filip (Microbiol Res 152:209-216, 1997), since then more bacterial laccases have been found. In this research, laccase-producing bacteria were screened from pulp and paper industry wastewater, bagass and sugarcane rhizosphere. Nutrient agar medium containing 0.5 mM of guaiacol was used. It was observed that the laccase-producing strains developed brown colour from which 16 strains of Bacillus were identified. One of the isolated strains was identified as Bacillus subtilis WPI based on the results of biochemical tests and 16S rDNA sequence analysis. This strain showed laccase-like activity towards the oxidizing substrates ABTS and guaiacol. In this study guaiacol was used as the substrate of laccase activity assay. For determination of laccase activity of this isolate guaiacol was used as a substrate of assay for the first time in this study. SDS-PAGE and Native-PAGE confirmed the presence of laccase.

Can polymer-degrading microorganisms solve the bottleneck of plastics' environmental challenges?

Increasing world population and industrial activities have enhanced anthropogenic pollution, plastic pollution being especially alarming. So, plastics should be recycled and/or make them biodegradable. Chemical and physical remediating methods are usually energy consuming and costly. In addition, they are not ecofriendly and usually produce toxic byproducts. Bioremediation is a proper option as it is cost-efficient and environmentally friendly. Plastic production and consumption are increasing daily, and, as a consequence, more microorganisms are exposed to these nonbiodegradable polymers. Therefore, investigating new efficient microorganisms and increasing the knowledge about their biology can pave the way for efficient and feasible plastic bioremediation processes. In this sense, omics, systems biology and bioinformatics are three important fields to analyze the biodegradation pathways in microorganisms. Based on the above-mentioned technologies, researchers can engineer microorganisms with specific desired properties to make bioremediation more efficient.

Socio-Environmental Determinants and Human Health Exposures in Arid and Semi-Arid Zones of Iran-Narrative Review.

Lifestyle is different in arid and semi-arid zones. However, where people are born and live have a lasting influence on their social and environmental exposure. This review focuses on the, various dimensions of environmental health imbalance inequality especially in significant environmental sources such as (ie, air, water, soil) among provinces that creates a big health gap in the center, East and the Southeast of Iran. Thus, the population of the arid and semi-arid zones of Iran is facing respiratory, cardiovascular, cancer and infection diseases linked to environmental problems such as chemical and microbial pollution due to air pollution and unsafe water sources, respectively. The prevalence of certain types of cancer such as skin, stomach, bladder, prostate and colorectal cancer together with some respiratory and cardiovascular diseases in arid and semiarid zones such as Kerman, Yazd, etc., has been reported in comparison with other provinces frequently. These impacts have effects on multiple levels of health security in those zones. Based on these concerns, we propose key questions that should guide research in the context of the socio environmental science to support science-based management actions in Iran and other similar semi-arid areas worldwide.

Cost analysis in laccase production.

In this paper the cost of producing the enzyme laccase by the white-rot fungus Trametes pubescens under both submerged (SmF) and solid-state fermentation (SSF) conditions was studied. The fungus was cultured using more than 45 culture medium compositions. The cost of production was estimated by analyzing the cost of the culture medium, the cost of equipment and the operating costs. The cost of the culture medium represented, in all cases, the highest contribution to the total cost, while, the cost of equipment was significantly low, representing less than 2% of the total costs. The cultivation under SSF conditions presented a final cost 50-fold lower than the one obtained when culturing under SmF conditions at flask scale. In addition, the laccase production under SSF conditions in tray bioreactors reduced the final cost 4-fold compared to the one obtained under SSF conditions at flask scale, obtaining a final price of 0.04 cent €/U.

Robust nanocarriers to engineer nanobiocatalysts for bioprocessing applications.

The synergistic integration of bio-catalysis engineering with nanostructured materials, as unique multifunctional carrier matrices, has emerged as a new interface of nanobiocatalysis (NBC). NBC is an emerging innovation that offers significant considerations to expand the designing and fabrication of robust catalysts at the nanoscale with improved catalytic characteristics for multipurpose bioprocessing applications. In addition, nanostructured materials with unique structural, physical, chemical, and functional entities have manifested significant contributions in mimicking the enzyme microenvironment. A fine-tuned enzyme microenvironment with an added-value of NBC offers chemo- regio- and stereo- selectivities and specificities. Furthermore, NBC is growing rapidly and will become a powerful norm in bio-catalysis with much controlled features, such as selectivity, specificity, stability, resistivity, induce activity, reaction efficacy, multi-usability, improved mass transfer efficiency, high catalytic turnover, optimal yield, ease in recovery, and cost-effectiveness. Considering the above critics and unique structural, physicochemical, and functional attributes, herein, we present and discuss advances in NBC and its bioprocessing applications in different fields. Briefly, this review is focused on four parts, i.e., (1) NBC as a drive towards applied nanobiocatalysts (as an introduction with opportunities), (2) promising nanocarriers to develop nanobiocatalysts, (3) applications in the fields of biotransformation, biofuel production, carbohydrate hydrolysis, bio-/nanosensing, detergent formulations, and extraction and purification of value-added compounds, and (4) current challenges, concluding remarks, and future trends.

New Type Biomembrane: Transport and Biodegradation of Reactive Textile Dye.

In traditional separation processes, there are environmental risks still because of the presence of toxic agents. Thus, a novel biomembrane microreactor named eco-green biomembrane (EgBM) was developed to perform the transport, biodegradation, and cleaning of a textile dye aqueous solution (3 mg/L) from the donor (i.e., textile dye) to the acceptor (i.e., laccase enzymes) phases. In the present work, Morchella esculenta pellets were used as carriers and degraders instead of using the traditional chemical carriers. The optimized EgBM was made of cellulose triacetate (16.1%) as a base polymer, 2-nitrophenyl octyl ether (25.2%) as a plasticizer, and M. esculenta fungus pellets (58.7%) as both carriers and degraders. A decoloration percentage of 98.6% ± 0.8 in 60 h was attained, which was due to two mechanisms: biosorption (15.4% ± 0.1) on fungal mycelium and biodegradation (83.2% ± 0.6) by laccase enzymes. The EgBM was achieved not only by the transport of reactive textile dyes used in the donor phase but also by the biodegradation and biosorption of the dyes.

A comprehensive study on the application of FeNi3@SiO2@ZnO magnetic nanocomposites as a novel photo-catalyst for degradation of tamoxifen in the presence of simulated sunlight.

Pharmaceutical compounds at trace concentrations are found in the environment, especially in drinking water and food, posing significant negative effects on humans as well as on animals. This paper aimed to examine the diagnostic catalytic properties and efficacy of a novel synthesized photocatalyst, namely FeNi3@SiO2@ZnO magnetic nanocomposite, for the removal of tamoxifen (TMX) from wastewater under simulated sunlight. According to the results, it was found that TMX was completely degraded operating under optimized conditions (i.e. pH = 7, catalyst dose = 0.01 g/L, initial TMX concentration = 20 mg/L and reaction time = 60 min). The reaction kinetics of TMX degradation followed a pseudo-first order kinetics model. The final by-products from the TMX photodegradation were water, carbon dioxide, acetic acid, nitroacetic acid methyl ester, 2-methyl-2-pentenal, and 4-methyl-2-pentanol. In addition, the synthesized photocatalyst could successfully performed five consecutive photodegradation cycles. The obtained results revealed that the synthesized FeNi3@SiO2@ZnO magnetic nanocomposite holds a great potential to be applied as a photocatalyst for the degradation of TMX on an industrial scale.

Using biotechnology in the laboratory: Using an immobilized-laccase reactor-system to learn about wastewater treatment.

This article includes a practical guide, which was used to teach the phenomenon of immobilization of enzymes and their subsequent use for discoloration of dyes to under-graduate students of Biotechnology at the Rovira i Virgili University (Tarragona, Spain). Alginate was selected as a support for the immobilization of laccase. Remazol Brilliant Blue R (RBBR) was used as a substrate for laccase because it is easy to see the color change from dark blue to light blue or no color depending on the discoloration ability of the enzyme. Colorimetric methods to determine the amount of encapsulated enzyme, the effect of the immobilization, and the rate of the discoloration were also pursued by the students.

A promising laccase immobilization approach for Bisphenol A removal from aqueous solutions.

The immobilization of crude laccase from Trametes pubescens by glutaraldehyde crosslinking prior to entrapment into Ca-alginate beads increased the immobilization yield by 30% and reduced the leaking by 7-fold compared to the immobilization with no crosslinking. The performance of the newly developed biocatalyst to degrade Bisphenol A (BPA) from aqueous solutions was tested. Thus, operating at optimal conditions (i.e. pH 5, 30 °C, 20 mg L-1 BPA and 1500 U L-1 laccase), a BPA removal higher than 99% in 2 h was achieved. This value is higher than those reported to date for BPA removal by immobilized laccases. In addition, the biocatalyst was able to remove BPA in 10 successive batches with an efficiency higher than 70% at the end of the last batch. BPA adsorption on the alginate beads was negligible, therefore BPA removal was only due to laccase action. Moreover, Fourier-transform Infrared (FTIR) spectroscopy suggested BPA transformation by laccase.

Antifungal and anti-mycotoxin efficacy of biogenic silver nanoparticles produced by Fusarium chlamydosporum and Penicillium chrysogenum at non-cytotoxic doses.

The cell-free culture filtrate (CFF) of the fungi Fusarium chlamydosporum NG30 and Penicillium chrysogenum NG85 was tested to synthesize silver nanoparticles (AgNPs). The synthesized AgNPs were further characterized by means of transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier transform infra-red (FTIR) spectroscopy. TEM revealed their spherical shape, homogeneity and a size range between 6 and 26 nm for F. chlamydosporum AgNPs (FAgNPs) and from 9 to 17.5 nm for P. chrysogenum AgNPs (PAgNPs). DLS showed that the diameter of FAgNPs was narrower than that of PAgNPs. FTIR spectroscopy indicated that the functional groups present in the CFF might be responsible for the reduction of silver ions to form stabilized protein-capped AgNPs. In addition, the AgNPs showed notable antifungal activity and potency in thwarting mycotoxin production. Thus, using Aspergillus flavus as a test microorganism the minimum inhibitory concentration (MIC) was 48, 45 and 50 µg/mL for FAgNPs, PAgNPs and the antifungal compound itraconazole, respectively. Also, when testing Aspergillus ochraceus FAgNPs, PAgNPs and itraconazole led to MIC values of 51, 47 and 49 µg/mL, respectively. The statistical MIC values to inhibit completely the total aflatoxin production by A. flavus were 5.9 and 5.6 µg/mL for FAgNPs and PAgNPs, respectively, and to inhibit the ochratoxin A production by A. ochraceus 6.3 and 6.1 µg/mL for FAgNPs and PAgNPs, respectively. The cytotoxicity assay of the AgNPs on human normal melanocytes (HFB 4) revealed a cell survival of 80% and 75% at a concentration of 6 µg/mL for FAgNPs and PAgNPs, respectively.

Evaluation of antimicrobial activity of Terfezia arenaria extracts collected from Saharan desert against bacteria and filamentous fungi.

Different desert truffles, collected from Algerian Saharan soils, were identified and their capacity to produce bioactive substances with antimicrobial activity was analyzed. Based on morphological characterization using Melzer's reagent staining, the collected strains were identified as Terfezia arenaria. The bioactive substances from T. arenaria were extracted using the following techniques: maceration with methanol and Soxhlet with dichloromethane. The former led to a yield much higher than that of the latter (i.e., 15% and 0.48%, respectively). Both extracts presented antifungal activities against all the tested strains (i.e., A. niger, Penicillium sp., and C. albicans). However, the dichloromethane extracts showed much higher antibacterial activities against all the tested bacteria (i.e., S. aureus, E. faecalis, E. coli, and P. aeruginosa) than the methanol extracts. The thin layer chromatography of both extracts confirmed the presence of polyphenols and flavonoids.

Synthesis and characterization of nanoparticles and composites as bactericides.

In the present study, SiO2-TiO2 hybrid nanomaterial and zeolite-TiO2 (Z-TiO2) composites were synthesized by the sol-gel method. Then, the antibacterial activity of the above-mentioned synthesized materials, SiO2 and zeolite (Z) was investigated by the disk diffusion method using Echerichia coli and Enterobacter aerogenes as test microorganisms. All the materials showed antibacterial activity against E. coli with 7.2, 10.7, 3.5 and 8.2 mm of inhibition zone for SiO2-TiO2 hybrid nanomaterial, SiO2, zeolite and Z-TiO2 composite, respectively. However, none of them showed antibacterial activity against E. aerogenes. The obtained results pointed out that these natural-based materials (i.e. Z, SiO2, Z-TiO2 and SiO2-TiO2), known to be noncarcinogenic and nontoxic, can be used as disinfectants against E. coli (an important indicator of the bacteriological quality of water) as safe and eco-friendly alternatives to chlorine.