Searching for Chemical Agents Suppressing Substrate Microbiota in White-Rot Fungi Large-Scale Cultivation.

Edible fungi are a valuable resource in the search for sustainable solutions to environmental pollution. Their ability to degrade organic pollutants, extract heavy metals, and restore ecological balance has a huge potential for bioremediation. They are also sustainable food resources. Edible fungi (basidiomycetes or fungi from other divisions) represent an underutilized resource in the field of bioremediation. By maximizing their unique capabilities, it is possible to develop innovative approaches for addressing environmental contamination. The aim of the present study was to find selective chemical agents suppressing the growth of microfungi and bacteria, but not suppressing white-rot fungi, in order to perform large-scale cultivation of white-rot fungi in natural unsterile substrates and use it for different purposes. One application could be the preparation of a matrix composed of wooden sleeper (contaminated with PAHs) and soil for further hazardous waste bioremediation using white-rot fungi. In vitro microbiological methods were applied, such as, firstly, compatibility tests between bacteria and white-rot fungi or microfungi, allowing us to evaluate the interaction between different organisms, and secondly, the addition of chemicals on the surface of a Petri dish with a test strain of microorganisms of white-rot fungi, allowing us to determine the impact of chemicals on the growth of organisms. This study shows that white-rot fungi are not compatible to grow with several rhizobacteria or bacteria isolated from soil and bioremediated waste. Therefore, the impact of several inorganic materials, such as lime (hydrated form), charcoal, dolomite powder, ash, gypsum, phosphogypsum, hydrogen peroxide, potassium permanganate, and sodium hydroxide, was evaluated on the growth of microfungi (sixteen strains), white-rot fungi (three strains), and bacteria (nine strains) in vitro. Charcoal, dolomite powder, gypsum, and phosphogypsum did not suppress the growth either of microfungi or of bacteria in the tested substrate, and even acted as promoters of their growth. The effects of the other agents tested were strain dependent. Potassium permanganate could be used for bacteria and Candida spp. growth suppression, but not for other microfungi. Lime showed promising results by suppressing the growth of microfungi and bacteria, but it also suppressed the growth of white-rot fungi. Hydrogen peroxide showed strong suppression of microfungi, and even had a bactericidal effect on some bacteria, but did not have an impact on white-rot fungi. The study highlights the practical utility of using hydrogen peroxide up to 3% as an effective biota-suppressing chemical agent prior to inoculating white-rot fungi in the large-scale bioremediation of polluted substrates, or in the large-scale cultivation for mushroom production as a foodstuff.

Mathematical Model Coupled to Neural Networks Calculates the Extraction Recovery of Polycyclic Aromatic Hydrocarbons in Problematic Matrix.

Unknown extraction recovery from solid matrix samples leads to meaningless chemical analysis results. It cannot always be determined, and it depends on the complexity of the matrix and properties of the extracted substances. This paper combines a mathematical model with the machine learning method-neural networks that predict liquid extraction recovery from solid matrices. The prediction of the three-stage extraction recovery of polycyclic aromatic hydrocarbons from a wooden railway sleeper matrix is demonstrated. Calculation of the extraction recovery requires the extract's volume to be measured and the polycyclic aromatic hydrocarbons' concentration to be determined for each stage. These data are used to calculate the input values for a neural network model. Lowest mean-squared error (0.014) and smallest retraining relative standard deviation (20.7%) were achieved with the neural network setup 6:5:5:4:1 (six inputs, three hidden layers with five, five, and four neurons in a layer, and one output). To train such a neural network, it took less than 8000 steps-less than a second--using an average-performance laptop. The relative standard deviation of the extraction recovery predictions ranged between 1.13 and 5.15%. The three-stage recovery of the extracted dry sample showed 104% of three different polycyclic aromatic hydrocarbons. The extracted wet sample recovery was 71, 98, and 55% for phenanthrene, anthracene, and pyrene, respectively. This method is applicable in the environmental, food processing, pharmaceutical, biochemical, biotechnology, and space research areas where extraction should be performed autonomously without human interference.

ß-Glucan from Saccharomyces cerevisiae Induces IFN-γ Production In Vivo in BALB/c Mice.

AIM: ß-Glucan is one of the most abundant polymers in nature and has been established as an immunomodulator. This compound has notable physiological effects on mammalian immune systems, including anti-tumor and anti-infective activities and can activate the immune response. It is considered that the immune-stimulating activities of ß-glucan can depend on physicochemical parameters, such as molecular size. Saccharomyces cerevisiae, also known as baker's yeast, is a frequently used source of ß-glucan. The aim of the experiments was to investigate how different Saccharomyces cerevisiae ß-glucan preparations with different molecular size affect interferon-gamma (IFN-γ) production in BALB/c mice. MATERIALS AND METHODS: In vivo and in vitro BALB/c mouse models were used for the investigations. Different ß-glucan preparations were orally administrated in the in vivo experiments. IFN-γ production in BALB/c mice was analyzed by enzyme-linked immunosorbent assay and measuring interferon-γ RNA concentration. RESULTS: The results showed that orally-administered ß-glucan from S. cerevisiae enhanced IFN-γ production in BALB/c mice in the in vivo model, but not by mouse leukocytes in vitro. Moreover, water-soluble ß-glucan enhanced IFN-γ production more effectively than did particulate ß-glucan. CONCLUSION: IFN-γ plays an important role in immunity against viral and bacterial infections. Our experiments have shown that ß-glucan preparations enhance IFN-γ production in BALB/c mice and can be potentially used for immune system stimulation in mammals. Current results may be used to develop soluble ß-glucan nutritional supplements.

Purification and partial characterization of a novel ß-1,3-endoglucanase from Streptomyces rutgersensis.

A ß-1,3-endoglucanase produced by Streptomyces rutgersensis was purified to a homogeneity by the fractional precipitation with ammonium sulfate, ion exchange chromatography on Q-Sepharose and hydrophobic chromatography on Butyl Sepharose. A typical procedure provided 11.74-fold purification with 12.53 % yield. SDSPAGE of the purified protein showed one protein band. The exact molecular mass of the enzyme obtained by mass spectrometry was 41.25 kDa; the isoelectric point was between pH 4.2­4.4. The optimal ß-glucanase catalytic activity was at pH 7 and 50 °C. An enzyme was only active toward glucose polymers containing ß-1,3 linkages and hydrolyzed Saccharomyces cerevisiae cell wall ß-glucan in an endo-like way: reaction products were different molecular size ß-glucans, which were larger than glucose.