Selection and Optimization of Culture Medium for Exopolysaccharide Production by Coriolus (Trametes) Versicolor

Comprehensive review on recent trends and perspectives of natural exo-polysaccharides: Pioneering nano-biotechnological tools

Exopolysaccharides (EPSs), originating from various microbes, and mushrooms, excel in their conventional role in bioremediation to showcase diverse applications emphasizing nanobiotechnology including nano-drug carriers, nano-excipients, medication and/or cell encapsulation, gene delivery, tissue engineering, diagnostics, and associated treatments. Acknowledged for contributions to adsorption, nutrition, and biomedicine, EPSs are emerging as appealing alternatives to traditional polymers, for biodegradability and biocompatibility. This article shifts away from the conventional utility to delve deeply into the expansive landscape of EPS applications, particularly highlighting their integration into cutting-edge nanobiotechnological methods. Exploring EPS synthesis, extraction, composition, and properties, the discussion emphasizes their structural diversity with molecular weight and heteropolymer compositions. Their role as raw materials for value-added products takes center stage, with critical insights into recent applications in nanobiotechnology. The multifaceted potential, biological relevance, and commercial applicability of EPSs in contemporary research and industry align with the nanotechnological advancements coupled with biotechnological nano-cleansing agents are highlighted. EPS-based nanostructures for biological applications have a bright future ahead of them. Providing crucial information for present and future practices, this review sheds light on how eco-friendly EPSs derived from microbial biomass of terrestrial and aquatic environments can be used to better understand contemporary nanobiotechnology for the benefit of society.

Microalgae Strain Porphyridium purpureum for Nutrient Reduction in Dairy Wastewaters

This paper has approached the study of dairy wastewater treatment and the simultaneous biocompound production by Porphyridium purpureum under continuous light and under a day–night cycle. The main goals were to achieve a reduction in the lactose content of the cheese wastewater that was tested and, at the same time, to obtain added value from the produced compounds, so as to increase the economic value of the process. The results show that biomass production increases proportionally with the concentration of lactose for both of the illumination options. The lactose concentration in the waste stream was reduced over 90% in just 7 days. The exopolysaccharide concentration in the growth medium increased with lactose availability. For the samples that were under constant light stress, the concentration of phycobiliproteins was highest when there was small amounts of lactose in the medium. The content of pigments was higher in the case of the day–night cycle of illumination; these being affected by stress factors such as continuous light and high lactose concentration. The results that were obtained prove that dairy wastewaters that are rich in lactose can be used efficiently for the growth of Porphyridium purpureum, achieving an increase in the biomass concentration and a large reduction of the lactose from this waste stream while obtaining a microalgae biomass that is rich in valuable compounds.

Optimization of the Decolorization of the Reactive Black 5 by a Laccase-like Active Cell-Free Supernatant from Coriolopsis gallica

The textile industry generates huge volumes of colored wastewater that require multiple treatments to remove persistent toxic and carcinogenic dyes. Here we studied the decolorization of a recalcitrant azo dye, Reactive Black 5, using laccase-like active cell-free supernatant from Coriolopsis gallica. Decolorization was optimized in a 1 mL reaction mixture using the response surface methodology (RSM) to test the influence of five variables, i.e., laccase-like activity, dye concentration, redox mediator (HBT) concentration, pH, and temperature, on dye decolorization. Statistical tests were used to determine regression coefficients and the quality of the models used, as well as significant factors and/or factor interactions. Maximum decolorization was achieved at 120 min (82 ± 0.6%) with the optimized protocol, i.e., laccase-like activity at 0.5 U mL−1, dye at 25 mg L−1, HBT at 4.5 mM, pH at 4.2 and temperature at 55 °C. The model proved significant (ANOVA test with p < 0.001): coefficient of determination (R²) was 89.78%, adjusted coefficient of determination (R²A) was 87.85%, and root mean square error (RMSE) was 10.48%. The reaction conditions yielding maximum decolorization were tested in a larger volume of 500 mL reaction mixture. Under these conditions, the decolorization rate reached 77.6 ± 0.4%, which was in good agreement with the value found on the 1 mL scale. RB5 decolorization was further evaluated using the UV-visible spectra of the treated and untreated dyes.

Trametes versicolor immobilized on rotating biological contactors as alternative biological treatment for the removal of emerging concern micropollutants

White rot fungi have been studied for the removal of micropollutants of emerging concern from wastewater during the last decade. However, several issues need to be overcome for its plausible implementation at full-scale installations such as the addition of supplementary substrates, the partial re-inoculation of fresh fungi or the use of extended hydraulic retention times. This work proposes the immobilization of Trametes versicolor on rotating biological contactors at bench scale (flowrates of 10 L/d and reactor capacity of 10 L) for the treatment of different urban wastewater. This type of bioreactor achieved remarkable reductions of the total organic carbon loading of the wastewater (70-75%) in a wide range of C:N and C:P ratios with limited addition of supplementary substrates, non-refreshment of the fungal biomass and only 1-day of hydraulic retention. The addition of gallic acid as quinone-like mediator and quelated iron and manganese complexes increased the removal of pharmaceutical micropollutants mediated by the so-called advanced bio-oxidation process. The immobilization of Trametes versicolor on rotating biological contactors also showed a remarkable stabilization of the fungi during the continuous treatment of different urban wastewater under non-sterile conditions. Thus, this system is a sound alternative for biological urban wastewater treatment with pharmaceutical removal because overcome all the problems usually associated with the water treatment technologies based on white rot fungi that makes difficult the scaling-up of the process and its implementation in full scale wastewater treatment plants.

UV/H2O2/Ferrioxalate Based Integrated Approach to Decolorize and Mineralize Reactive Blue Dye: Optimization Through Response Surface Methodology

The decolorization and mineralization of Reactive Blue 222 dye was studied using UV/H2O2/ferrioxalate approach in combination with Pleorotus ostreatus. The dye was decolorized by UV/H2O2/ferrioxalate based advanced oxidation process (AOP) at different levels of process variables dye concentration, catalyst dose, pH, reaction time and resultantly, 80% decolorization was achieved. Pleorotus ostreatus treatment enhanced the dye degradation up to 92% at optimum levels of pH, temperature, inoculum size, carbon and nitrogen sources at specific concentration. Response Surface Methodology (RSM) was employed for optimization under face-centered central composite design (CCD). Although both treatments were found efficient for the removal of dye, but on applying the integrated approach, 96% dye removal was obtained which led to complete degradation of the dye. FTIR analysis confirmed the degradation of dye into low mass compounds. The water quality assurance parameters were measured to assess the mineralization efficiency. A significant reduction in COD (94%) and TOC (92%) were found when dye was degraded integrated approach. A phytotoxicity analysis on Pisum sativum plant revealed the non-toxic behavior of metabolites produced. Results revealed that the integrated approach is highly promising for the decolorization and mineralization of the Reactive Blue 222 dye and is also extendable to treat the dye in textile wastewater.

Current status of biotechnological production and applications of microbial exopolysaccharides

Microbial exopolysaccharides (EPS) are an abundant and important group of compounds that can be secreted by bacteria, fungi and algae. The biotechnological production of these substances represents a faster alternative when compared to chemical and plant-derived production with the possibility of using industrial wastes as substrates, a feasible strategy after a comprehensive study of factors that may affect the synthesis by the chosen microorganism and desirable final product. Another possible difficulty could be the extraction and purification methods, a crucial part of the production of microbial polysaccharides, since different methods should be adopted. In this sense, this review aims to present the biotechnological production of microbial exopolysaccharides, exploring the production steps, optimization processes and current applications of these relevant bioproducts.

Innovative production of fungal pulp from Trametes versicolor and its application in a fungal paper box containing clove oil

The aims of this study were to develop fungal pulp from Trametes versicolor (white-rot fungi) and apply it with clove oil in a paper box to inhibit mold growth on the surface of peanuts. Broken rice media with different sugar solutions (2-10% w w^-1) were prepared and then inoculated with T. versicolor mycelium at amounts from 0.5 to 1.5% w w^-1. Fungal pulp and commercial paper (50 g) at different ratios (100:0, 70:30, 50:50, 30:70 and 0:100) were mixed and prepared before being placed into a stainless box (5 cm long by 5 cm wide). For the antimicrobial activity against Aspergillus flavus on peanuts, a paper box was incorporated with 2.5, 5 and 7.5% w w^-1 of clove oil, eugenol, caryophyllene, and a combination of eugenol and caryophyllene at ratios of 7:1, 4:4, and 1:7. Results indicated that the highest fungal pulp biomass of T. versicolor in broken rice media was found when using 6% sugar with 1% mycelium inoculums. Fungal pulp and commercial paper at the ratio of 70:30 produced the highest value of hardness. The paper box containing clove oil at 7.5% w w^-1 inhibited A. flavus on peanuts for at least 28 days while the control had mold growth within 3 days. Combining eugenol and caryophyllene, the main components of clove oil, at the ratio of 7:1 (7.5% w w^-1) in the paper box should be a key factor to inhibit A. flavus during storage.

Structural and thermal analysis of a hyper-branched exopolysaccharide produced by submerged fermentation of mushroom mycelium

An exopolysaccharide (PTR-EPS1) purified from the culture medium of the mycelial fermentation of Pleurotus tuber-regium had a weight-average molecular mass of 173.6 kDa and a radius of 55.6 nm.

Decolorization and detoxification of two textile industry effluents by the laccase/1-hydroxybenzotriazole system

The aim of this work was to determine the optimal conditions for the decolorization and the detoxification of two effluents from a textile industry-effluent A (the reactive dye bath Bezactive) and effluent B (the direct dye bath Tubantin)-using a laccase mediator system. Response surface methodology (RSM) was applied to optimize textile effluents decolorization. A Box-Behnken design using RSM with the four variables pH, effluent concentration, 1-hydroxybenzotriazole (HBT) concentration, and enzyme (laccase) concentration was used to determine correlations between the effects of these variables on the decolorization of the two effluents. The optimum conditions for pH and concentrations of HBT, effluent and laccase were 5, 1 mM, 50 % and 0.6 U/ml, respectively, for maximum decolorization of effluent A (68 %). For effluent B, optima were 4, 1 mM, 75 %, and 0.6 U/ml, respectively, for maximum decolorization of approximately 88 %. Both effluents were treated at 30 °C for 20 h. A quadratic model was obtained for each decolorization through this design. The experimental and predicted values were in good agreement and both models were highly significant. In addition, the toxicity of the two effluents was determined before and after laccase treatment using Saccharomyces cerevisiae, Bacillus cereus, and germination of tomato seeds.

Studies on structural and physical characteristics of a novel exopolysaccharide from Pseudozyma sp. NII 08165

The aim of this work was to study the production of exopolysaccharide (EPS) from a novel ustilaginomycetes yeast strain Pseudozyma sp. NII 08165. The culture produced 3.5g/l EPS on fourth day of fermentation in a glucose-based medium. The structural characterization revealed that the EPS was a polymer of glucose, galactose and mannose in the ratio of 2.4:5.0:2.6 with a molecular weight of 1.7MDa. The pseudoplastic behaviour of aqueous EPS with a thermal stability up to 220°C indicated its potential utility as a thickening or gelling agent in food industry. SEM studies of the EPS showed that it had compact film-like structure, which could make it a useful in preparing plasticized films. The AFM studies showed that EPS had spike-shaped microstructure. Physical properties of the exopolysaccharide determined further indicated its possible potential in different industrial applications.

Fungal exopolysaccharide: production, composition and applications

Fungal exopolysaccharides (EPSs) have been recognized as high value biomacromolecules for the last two decades. These products, including pullulan, scleroglucan, and botryosphaeran, have several applications in industries, pharmaceuticals, medicine, foods etc. Although fungal EPSs are highly relevant, to date information concerning fungal biosynthesis is scarce and an extensive search for new fugal species that can produce novel EPSs is still needed. In most cases, the molecular weight variations and sugar compositions of fungal EPSs are dependent to culture medium composition and different physical conditions provided during fermentation. An inclusive and illustrative review on fungal EPS is presented here. The general outline of the present work includes fungal EPS production, their compositions and applications. An emphasis is also given to listing out different fungal strains that can produce EPSs.

Application of response surface methodology to optimize decolourization of dyes by the laccase-mediator system

Response surface methodology (RSM) was applied to optimize the decolourization of 3 dyes belonging to 3 dye families such as reactive black 5 (diazoic), indigo carmine (indigoid) and aniline blue (anthraquinonic). Crude laccase from Trametes trogii and the laccase-mediator 1-hydroxybenzotriazole (HBT) were used in this study. Box-Behnken design using RSM with six variables namely pH, temperature, enzyme concentration, HBT concentration, dye concentration and incubation time was used in this study to optimize significant correlation between the effects of these variables on the decolourization of reactive black 5 (RB5), indigo carmine (IC) and aniline blue (AB). The optimum of pH, temperature, laccase, HBT, RB5 and reaction time were 4.5, 0.5 U ml(-1), 0.5 mM, 100 mg ml(-1) and 150 min respectively, for a maximum decolourization of RB5 (about 92.92% ± 7.21). Whereas, the optimum decolourization conditions of both IC (99.76% ± 7.75) and AB (98.44% ± 10) were: pH 4.5, temperature of 45 °C, enzyme concentration of 0.1 U ml(-1) and 0.5 U ml(-1), HBT concentration of 0.9 mM and 0.5 mM, dye concentration of 60 mg l(-1) and reaction time of 150 and 90 min, respectively. The experimental values were in good agreement with the predicted ones and the models were highly significant, the correlation coefficient (R(2)) being 0.864, 0.663 and 0.776 for RB5, IC and AB, respectively. In addition, when the kinetic parameters for the three dyes decolourization were calculated according to Hannes-Wolf plot, the following values were obtained: Km of 268.4, 47.94 and 44.64 mg l(-1) then V(max) of 35.58, 10.43 and 9.23 mg l(-1) min for the RB5, IC and AB decolourizations by laccase, respectively.

Biological treatment of eucalypt spent sulphite liquors: a way to boost the production of second generation bioethanol

The fermentation of reducing sugars from hardwood (eucalypt) spent sulphite liquor (HSSL) into ethanol by Pichia (Scheffersomyces) stipitis is hindered by concomitant inhibitors of microbial metabolism. The conditions for the HSSL biological treatment step by Paecilomyces variotii were evaluated and optimised. Two different strategies of reactor operation were compared using single batch (B) and sequential batch reactor (SBR). Biological treatment of HSSL in the SBR revealed the best results with respect to the removal of microbial inhibitors. Also, most of inhibitory compounds, acetic acid, gallic acid, pyrogallol, amongst others, were removed from HSSL by P. variotii before the ethanol fermentation. The bio-detoxified HSSL was subjected to a successful fermentation by P. stipitis, attaining a maximum ethanol concentration of 2.4 g L(-1) with a yield of 0.24 g ethanol g sugars(-1).

Application of statistical experimental methodology to optimize reactive dye decolourization by commercial laccase

Three-level Box-Behnken factorial design with three factors (pH, temperature and enzyme concentration) combined with response surface methodology (RSM) was applied to optimize the dye degradation of reactive red 239 (RR239), reactive yellow 15 (RY15) and reactive blue 114 (RB114) dyes by commercial laccase. Mathematical models were developed for each dye showing the effect of each factor and their interactions on colour removal. The model predicted for RY15 that a decolourization above 90% (after 24h) could be obtained when the enzyme concentration, temperature and pH were set at 109.8U/L, 39.2 degrees C and 6.6, respectively; whilst for RB114 and RR239 the temperature and enzyme concentration did not affect the decolourization (>90%) in the considered range and optimum pH value was found at 5.5-7.0 and 7.0-7.5, respectively. These predicted values were also experimentally validated. Average final values of responses were in good agreement with calculated values, thus confirming the reliability of the models of RY15, RB114 and RR239 decolourization.

Characterisation and bioactivity of protein-bound polysaccharides from submerged-culture fermentation of Coriolus versicolor Wr-74 and ATCC-20545 strains

The protein-bound polysaccharides of Coriolus versicolor (CPS) have been reported to stimulate overall immune functions against cancers and various infectious diseases by activating specific cell functions. A New Zealand isolate (Wr-74) and a patented strain (ATCC-20545) of C. versicolor were compared in this study. The fruit bodies of both strains were grown for visual verification. Both strains were grown in submerged-culture using an airlift fermentor with milk permeate as the base medium supplemented with glucose, yeast extract and salt. Metabolic profiles of both strains obtained over 7-day fermentation showed very similar trends in terms of biomass production (8.9-10.6 mg/ml), amounts of extracellular polysaccharide (EPS) from the culture medium (1150-1132 microg/ml), and intracellular polysaccharide (IPS) from the mycelium (80-100 microg/ml). Glucose was the dominant sugar in both EPS and IPS, and the polymers each consisted of three molecular weight fractions ranging from 2 x 10(6) to 3 x 10(3 )Da. Both the EPS and IPS were able to significantly induce cytokine production (interleukin 12 and gamma interferon) in murine splenocytes in vitro. Highest levels of interleukin 12 (291 pg/ml) and gamma interferon (6,159 pg/ml) were obtained from samples containing Wr-74 IPS (0.06 microg/ml) and ATCC 20545 IPS (0.1 microg/ml), respectively. The results indicated that lower levels of EPS and IPS generally resulted in higher immune responses than did higher polymer concentrations.