Dry Mycelium Research Articles

Methyl Red degradation by a subseafloor fungus Schizophyllum commune 15R-5-F01: efficiency, pathway, and product toxicity.

Synthetic dyes pose a significant environmental threat due to their complex structures and resistance to microbial degradation. S. commune 15R-5-F01 exhibited over 96% degradation efficiency of Methyl Red in a medium with 100 mg L-1 Methyl Red within 3 h. The fungus demonstrated adaptability to various environmental conditions, including different pH levels, temperatures, oxygen concentrations, salinity, and heavy metals. S. commune 15R-5-F01 is capable of achieving repeated cycles of Methyl Red reduction with sustained degradation duration minimum of 6 cycles. It showed a maximum Methyl Red biodegradation capacity of at least 558 mg g-1 dry mycelia and a bioadsorption capacity of 57 mg g-1. Gas chromatography-mass spectrometry analysis confirmed the azo reduction of Methyl Red into N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Enzymatic activity assays indicated the involvement of lignin peroxidases, laccases, and manganese peroxidase in the biodegradation process. Phytotoxicity tests on Triticum eastivum, Oryza sativa, and Vigna umbellata seeds revealed reduced toxicity of the degradation products compared to Methyl Red. This study identifies S. commune 15R-5-F01 as a viable candidate for the sustainable degradation of synthetic dyes in industrial wastewater.

Культуральные признаки и рост на сложных жидких питательных средах перспективного грибного штамма антагониста М-24 Penicillium sp. возбудителя фомоза подсолнечника

A microbiological method decreasing harmfulness of Phoma rot on sunflower, which is one of the prevailing disease in all regions of crop cultivation, is developed at the V.S. Pustovoit All-Russian Research Institute of Oil Crops. The cultural traits of antagonist fungus of phoma pathogen on sunflower М-24 Penicillium sp. on three agar media and strain growth on four complicated liquid nutrient media were studied at surface cultivation of a strainproducer to develop elements of technological regimen for production of microbiopreparations in a preparative form wettable powder. On the tenth days of cultivation at +25 °С temperature, strong growth of the fungus with abundant conidial sporulation and maximal diameter of a colony was noted on the agar medium by Rudakov. The medium by Rudakov is stated as optimal among complicated liquid nutrient media. In ten days of the surface cultivation, a thick folded mycelial film with an abundant sporulation was formed on this medium as well as maximal weight of a dry mycelium – 1.44 g per 100 ml of nutrient medium vs. 0.20–1.39 g on the other media.

Copper ion sorption ability of Alternaria alternata (Fr.) Keissl. and Fusarium oxysporum Schltdl. micromycetes

Our analysis of metabolic and ecological features of fungi indicates a high bioremediation potential of fungal mycelium. The relevance of the problems solved in this work is conditioned by insufficiently studied mechanisms and conditions of micromycetal activity on heavy metal detoxication. The effect of copper on the development of two micromycete species, namely, melanised Alternaria alternata (Fr.) Keissl., 1912 and hyaline Fusarium oxysporum Schltdl., 1824 cultivated on Czapek agar (with 2 or 3% sucrose) was compared; the ability of mycelium to sorb copper cations when grown in a liquid culture with 0, 0.05, 0.1, 0.25, and 0.5 mg Cu2+ / L was evaluated. F. oxysporum had noticeable advantages in terms of growth rate, tolerance, conidia production on medium with Cu2+. The effective concentration of copper (EC50), indicating the resistance of the fungus, increased for F. oxysporum by 1.5 times with increasing sucrose content in the medium. The melanised culture of A. alternata was superior to F. oxysporum in terms of sorption capacity. The percentage of Cu2+ extraction by fungal mycelium from the medium reached 40% in the case of F. oxysporum and twice as much in the case of A. alternata . The vast majority of copper was sorbed by the cell walls of hyphae and washed away by water. A small amount (a maximum of 0.16 µg Cu2+ /g dry mycelium of A. alternate ) penetrated inside the mycelial cells. F. oxysporum, which had no intracellular protective melanins, accumulated Cu2+ (2 to 14 times) less. The results show that the mechanisms of resistance to Cu2+ and sorption are different in the studied species: in Fusarium they are determined mainly by the barrier functions of hyphae cell walls, while in Alternaria melanin plays a significant role in protection against Cu toxic action.

Heavy Metal Remediation by Dry Mycelium Membranes: Approaches to Sustainable Lead Remediation in Water.

Lead contamination poses significant and lasting health risks, particularly in children. This study explores the efficacy of dried mycelium membranes, distinct from live fungal biomass, for the remediation of lead (Pb(II)) in water. Dried mycelium offers unique advantages, including environmental resilience, ease of handling, biodegradability, and mechanical reliability. The study explores Pb(II) removal mechanisms through sorption and mineralization by dried mycelium hyphae in aqueous solutions. The sorption isotherm studies reveal a high Pb(II) removal efficiency, exceeding 95% for concentrations below 1000 ppm and ∼63% above 1500 ppm, primarily driven by electrostatic interactions. The measured infrared peak shifts and the pseudo-second-order kinetics for sorption suggests a correlation between sorption capacity and the density of interacting functional groups. The study also explores novel surface functionalization of the mycelium network with phosphate to enhance Pb(II) removal, which enables remediation efficiencies >95% for concentrations above 1500 ppm. Scanning electron microscopy images show a pH-dependent formation of Pb-based crystals uniformly deposited throughout the entire mycelium network. Continuous cross-flow filtration tests employing a dried mycelium membrane demonstrate its efficacy as a microporous membrane for Pb(II) removal, reaching remediation efficiency of 85-90% at the highest Pb(II) concentrations. These findings suggest that dried mycelium membranes can be a viable alternative to synthetic membranes in heavy metal remediation, with potential environmental and water treatment applications.

Morphological Variability of the Curvularia lunata Associated with Grain Discoloration of Rice

Rice is an important staple crop and India is the largest grower in the world. Rice suffers from many diseases caused by fungi of which grain discoloration disease is a complex disease due to infection by certain microorganisms on the glumes, kernels, or both. Curvularia lunata is a one of major fungal plant pathogen that infects rice and causes grain discolouration. On the basis of cultural and morphological identification, 60 isolates of Curvularia lunata were collected from different locations of Karnataka. These isolates were grown on PDA media and were characterized for colony morphology. The Curvularia lunata isolates, maximum size of conidia was observed in Cl-22 (20.30 \(\mu\)m long ×10.90 \(\mu\)m wide) and maximum dry mycelium weight was observed in Cl-15 (482.22 mg), while poor sporulations (<1-10 conidia per microscope field) was noticed in Cl-17, 19, 28, 30, 45 and Cl-50.

Evaluation of Antifungal and anti-aflatoxin B1 efficacy of some crude extracts of Chamaerops humilis L. against Aspergillus flavus isolated from peanuts (Arachis hypogea L.)

The present study strengthens the food preservative potential of Chamaerops humilis extracts viz. hexane extract, chloroform extract, ethanol extract, chloroform extract, and methanol extract based on their antifungal, antiaflatoxin, and antioxidant efficacy. The isolation of molds from peanuts were carried out by the suspension-dilution technique and inoculation on agar medium. Antifungal determinations were conducted using the agar plate and liquid dilution methods. The effect of C. humilis L. extracts on the production of AFB1 was determined in a SMKY broth. The molds isolated were of the genera Aspergillus, Penicillium sp., Fusarium sp., and Alternaria sp. with A. flavus (BBH-6) which is identified as the highest AFB1 producer. The minimum inhibitory concentration of extracts against the toxigenic strain of A. flavus ranged between 3.00 mg/ml and 3.50 mg/ml. The extracts were found more efficacious as they inhibited the dry mycelium weight and aflatoxin production of the aflatoxigenic strain A. flavus (BBH-6) at lower concentrations. The extracts showed fungitoxic spectrum against four molds. The IC50 value of C. humilis L. ranged between 140.4 and 189.46 μg/mg, oxidation of linoleic acid was moderately inhibited by the extracts ranges between 53.54 and 69.33%, while their total phenolic content ranged between 47.80 and 115.71 μg/ml. Based on the findings of present investigation, C. humilis L. can be introduced as a proposed solution for formulating plant-based preservative food additives.

Находка теплолюбивого гриба Laetiporus sulphureus на территории г. Кирова

The first discovery of edible medicinal mushroom sulfur-yellow tinder on the territory of Kirov was registered. The local climate is characterized by the predominance of continental air of temperate latitudes and the weather is unstable in terms of temperatures and precipitation throughout the year. The region is characterized by a long moderately cold and snowy winter, a prolonged spring, early autumn and a moderately warm short summer. The average air temperature in the city of Kirov in winter is -9.2 оС, in summer it is +16.4 оС. The annual precipitation is 582 mm, of which 60–70% falls on the warm season. A pure culture of sulfur-yellow tinder was isolated using a fragment of the fruit body extracted from the inner part of the basidiocarp. The growth rate of isolate Laetiporus sulphureus NV on wort agar was 10.6 mm/day, on PGA – 7.8 mm/day. Species identification of the fungus was confirmed by molecular genetic method, the results were deposited in GenBank: ON130354.1. Phylogenetic analysis of species of the genus Laetiporus was carried out. The antibiotic activity of the isolate was studied. It was found that the fungus inhibits the growth of gram-positive bacteria i>Arthrobacter humicola 30H, Pedobacter agri 85Td and gram-negative species Pseudomonas cepacia 5809, Erwinia rhapontici DAG1-1. As a result of the liquid-phase ultivation of the L. sulphureus NV isolate on various liquid nutrient media using a magnetic stirrer, it was found that the greatest accumulation of biomass on 20 days of cultivation is observed on a liquid medium based on a decoction of barley husk with the addition of 2% glucose. The accumulation of dry mycelium biomass up to 1.64 g/L was revealed.

Screening and Optimisation of the Biodegradation Potential for Low Density Polyethylene (LDPE) Films by Fusarium Equiseti and Brevibacillus Parabrevis

The accumulation of low density polyethylene, used extensively in packaging for industrial and agricultural applications, in the ecosystem is a great threat. This study focuses on the isolation of micro-biota from the plastic polluted sites to screen and optimise their potential for low density polyethylene (LDPE) film biodegradation. Firstly, the plastic samples from soil dumping plastic debris and plastic polluted water were collected; then fungi and bacteria were isolated using potato dextrose agar media and nutrient agar media, respectively, while screening low density polyethylene film biodegradation performed on mineral salt media (MSM) using the isolated micro-biota. The measurement of the potential biodegradation was assessed by visual observation. The most microbial colonization for low density polyethylene films was identifying molecular which was then utilized for optimisation of the biodegradation processes with different parameters such as media type, inoculum size, shaking speed, different incubation temperature and pH at different incubation time. Then the weight loss in the LDPE films percentage was calculated measuring dry mycelium weight and bacterial absorbance. The results revealed that, among the isolated micro-biota fifteenth, the most colonization was Fusarium equiseti and Brevibacillus parabrevis depending on the scanning electron microsope (SEM) and Fourier transform infrared (FTIR) analysis, in addition to optimum media, inoculum size, shaking speed, incubation temperature, pH, MSM, 2 disks and 2 ml, 30˚ C and 35˚C, pH5 and pH7 for 30:20 days for F.equiseti and B.parabrevis, respectively. The overall results confirmed that F.equiseti and B.parabrevis from the plastic polluted sites play an essential role in low density polyethylene films biodegradation.

Advances in understanding the enzymatic potential and production of ochratoxin A of filamentous fungi isolated from cocoa fermented beans

In this work, we determined the degree of filamentous fungi contamination in cocoa fermented seeds and the fungal potential to produce enzymes that could contribute to the cocoa quality. Internal transcribed spacer amplicon sequencing (ITS) showed 11 different species with Byssochlamys spectabilis, Aspergillus niger, Aspergillus flavus, Aspergillus carbonarius, Circinella muscae and Penicillium citrinum as the most abundant species. Our results evidenced intra and inter-species differences in the enzymes production. Cellulases, β-glucosidase, ornithine decarboxylase and phenylalanine decarboxylase were the most diffused enzymes expressed in the 53 strains here studied. Moreover, A. niger (6/12), A. carbonarius (2/3), and P. citrinum (3/3) showed high pectinolytic activity. Remarkable was the amino decarboxylase activity of P. citrinum, and A. flavus strains. For the first time we reported the presence of B. spectabilis in cocoa fermented beans, which could play an important role in the biogenic amines formation. In addition, we explored the capability of the Aspergillus section Nigri strains, to produce ochratoxin A (OTA) in a cacao model system (CPMS) and in malt extract medium (MEL). We observed that CPMS, but not MEL, stimulated the OTA production in 6 out 15 strains of Aspergillus section Nigri, reaching values ranging between 1.70 and 4995 μg OTA kg−1 dry mycelium.

Assessment of Grain Extract Media on Mycelial Growth of Pleurotus spp. (P. Sapidus and P. Flabellatus)

The aim of present investigation pertains to study the impact of different culture media on the mycelial growth and dry weight of Pleurotus spp. Grains generally contains high nutritional content thereby decreases the harvesting period of mycelium and enhances dry weight. The study was conducted at Mushroom Laboratory Department Plant Pathology, S. V. P. University of Agriculture and Technology, Meerut, UP, India. Different crop grains were used as source of nutrition for fungus and added in PDA (media) in separate amount. Experiment was conducted in seven treatments with four replications. All the extracts observed varied mycelial growth of Pleurotus spp. After nine days maximum radial growth (90.00 mm) in both species (P. sapidus and P. flabellatus) was observed in barley extract media. The maximum growth rate (10.00 mm/day) of mycelium in P. sapidus and P. flabellatus was recorded in barley extract agar. Maximum dry mycelium weight (7.98 mg/100 ml & 8.35 mg/100 ml) of P. sapidus and P. flabellatus was observed in barley extract broth, respectively.

Inhibition of the Growth and Development of Sclerotinia sclerotiorum (Lib.) De Bary by Combining Azoxystrobin, Penicillium chrysogenum VKM F-4876d, and Bacillus Strains

Sclerotinia sclerotiorum (Lib.) de Bary is a plant pathogen with a wide host range, which causes significant yield and storage losses of edible roots and other plant products. Due to its ability to sclerotia formation, the efficient control of this pathogen is complicated. The study of five Bacillus strains (B. subtilis VKM B-3154D, VKM B-3155D, VKM B-3505D, VKM B-2998D, and B. amyloliquefaciens VKM B-3153D) showed their ability to produce polyene antibiotics suppressing the growth and development of plant pathogenic fungi. The maximum concentration of polyene compounds was revealed for B. subtilis VKM B-2998D. A high in vitro antifungal activity of a dry mycelium biomass (DMP) of Penicillium chrysogenum VKM F-4876D, B. subtilis VKM B-2998D, and their combination has been demonstrated in relation to S. sclerotiorum. A combined application of DMP (0.3 g/L) and azoxystrobin at low dosage (2.5 mg/L) showed a high suppressing activity towards S. sclerotiorum (100% growth inhibition) including inhibition of a sclerotia formation that may be useful for the development of efficient methods of crop protection against this plant pathogen. A high performance liquid chromatography (HPLC) analysis of DMP revealed the presence of mevastatin suggesting the mechanism of the DMP antifungal activity is based on the blocking of the ergosterol (the main component of fungal cell walls) biosynthesis. The results of the study provide a prerequisite to the development of biopreparations to control S. sclerotiorum, whose use may provide a reduction of concentrations of fungicides used in agriculture and the corresponding reduction of their negative xenobiotic impact on the environment and recovery of the ecological balance in the soil.

Medium optimization and downstream process design for the augmented yield of β-Carotene using fungi Blakeslea trispora

Purposeβ-Carotene is the most appropriate and significant precursor of vitamin A. Synthetic carotene supplements have been known to pose a threat to human health, making natural sources such as the indefensible choice for the production and extraction of carotene.Design/methodology/approachThis study considers Blakeslea trispora, a filamentous fungus, as a source of production of carotenoids by fermentation and wet and dry mycelium were used to analyse and obtain better extraction results.FindingsIn this study, natural oils such as soy oil and cottonseed oil were incorporated into fermentation media to increase the production of carotene. For the optimization process, Plackett–Burman and one-factor-at-a-time (OVAT) models were identified as being of great value.Originality/valueOVAT was carried out for corn starch because it plays a major role in the production of carotene and the corn starch at 30 g/L concentration has shown the maximum activity of 3.48 mg/gm. After optimizing process variables, submerged fermentation was eventually carried out under highly controlled media conditions. The resulting product was quantified using UV spectroscopy and extraction of carotene has been observed in the presence of various solvents. Among a range of solvents used, the methylene Di chloride produced-carotene at 86% recovery at a significantly lower temperature of 35°C.

Submerged culture fermentation of Colletotrichum lindemuthianum DSM 12250 as biotechnological strategy for fungal chitin biotransformation

Chitin and its derived products have great potential in various industries, such as biomedical, pharmaceutical, food, among others, due to its biodegradability, biocompatibility, null toxicity, and versatility. At present, these compounds are obtained by extraction with physical, chemical, or enzymatic processes. The fungus Colletotrichum lindemuthianum DSM 12250 which produces the enzyme chitin deacetylase (ClCDA), is proposed as an alternative for the biotransformation of fungal chitin. Chitin with a % N-Acetylation of 63.6% was obtained from the dry mycelium of Aspergillus niger that, based on analysis of Fourier transform infrared spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC), is structurally similar to commercial chitin. During fermentation in submerged culture, chitin presence was not found to generate inhibition in microbial growth or the activity of the ClCDA. The maximum enzymatic activity was 0.910 ± 0.002 U/mL and deacetylation of 20.9% were achieved. This was possible due to the enzymatic machinery of the fungus that includes CDA, endo-chitinases, and N-acetyl hexosaminidases. These compounds contribute to decreasing the substrate complexity, obtaining chitosan with a DDA of 57.3%. Submerged culture fermentation of Colletotrichum lindemuthianum DSM 12250 with fungal chitin as substrate represents a potential alternative for integrating different steps in the extraction of chitin-derived products while contributing to a cleaner and more efficient production.

Crude peptides extracted from dry mycelium of Penicillium chrysogenum serve as a micro-associated molecular pattern to induce systemic resistance against tobacco mosaic virus in tobacco

Control of viral diseases using systemic resistance-inducing microbes and microbial metabolites/molecules is an established alternative strategy for inhibiting plant viruses. However, the mechanisms whereby virus infection is inhibited and restricted in plants expressing systemic resistance remains poorly understood. We have previously reported that an aqueous extract of the dry mycelium of Penicillium chrysogenum (DMP) can be used to protect tobacco plants against Tobacco mosaic virus (TMV). In this study, we investigated the effect of crude peptides derived from DMP (PDMP) in protecting Nicotiana glutinosa against TMV. The number and diameter of TMV lesions in plants pre-treated with PDMP were fewer and smaller, respectively, than those in control plants. The elevated expressions of PAL, PTI5, PR-1a, NPR1, PR-1b, and PDF1.2 detected in the induced and systemic leaves following PDMP treatment indicated that the PDMP induced basal and systemic resistance in N. glutinosa. Callose deposition and TMV-N gene-triggered hypersensitive response (HR) at the site of the TMV infection were identified as key factors restricting the movement of viruses. The levels of N gene transcripts, as well as those of the TMV-N gene-triggered HR-related genes HSR203J, AOXa, SIPK, and ZFT1 increased more rapidly after being challenged with TMV in N. glutinosa plants pre-treated with PDMP compared with the control plants. However, we detected no significant difference between PDMP-treated and control plants with respect to TMV-induced callose deposition, indicating that PDMP enhances the resistance of N. glutinosa against TMV by accelerating TMV-N gene-triggered-HR rather than by priming callose deposition.

Environmental implications of the organic matter structure for white-rot fungus Pleurotus eryngii growth in a tropical climate

White-rot fungi (Pleurotus eryngii) are decomposers of lignocellulosic substrates. The relationship between the structure of humified organic matter and P. eryngii growth, is poorly understood. This study aimed to evaluate the relationship between the growth and development of white-rot fungi (P. eryngii) in two structurally different sources of humified organic matter. Fungus growth and development (mycelium diameter, fresh and dry mycelium mass, mycelium density, and biological yield) were evaluated in experiments with the application of humic substances (HS) extracted from vermicompost (VC) and peat. Both HS were characterized by CP/MAS 13C NMR spectroscopy associated with chemometrics analysis. The HS present different structural characteristics, with those extracted from VC having a predominance of functionalized C-aliphatics (carbohydrates), low hydrophobicity, and a 90% proportion of cellulose/hemicellulose carbon in the composition. HS extracted from peat have a predominance of C-aromatics (lignin fragments), higher hydrophobicity, and a proportion of lignin carbon of up to 80%. The results showed that P. eryngii growth is dependent on the C-cellulosic and C-lignin balance. HS extracted from lignin-rich peat regulates the fungus growth at initial times and sometimes inhibits the biological performance. The highly cellulosic HS from VC regulate the fungus growth at later times and its biological performance.

Biomass of a Psychrophilic Fungus as a Biocatalyst for Efficient Direct Esterification of Citronellol

A biomass-bound lipase from psychrophilic Chrysosporium pannorum A-1 is an efficient biocatalyst for direct esterification of β-citronellol and acetic acid in an organic solvent. The biomass is effectively produced by fungal submerged culture at 20 ℃, which results in lower energy consumption during the production of biocatalyst. Supplementation of the culture medium with calcium carbonate together with olive oil contributed to a significant increase in the active biomass of mycelium in one batch culture and increased the efficiency of the biocatalyst. Biomass-bound lipase showed high catalytic activity in a broad temperature range of 30–60 °C and stability up to 70 °C. A maximum molar conversion value of 98% was obtained at 30 °C in n-hexane using a 2:1 alcohol-to-acid molar ratio and 3% w/v of the biocatalyst within 24 h. The high equimolar concentration of the substrates (200 mM) did not have an adverse effect on mycelial biomass activity. Dry mycelium of C. pannorum is a promising biocatalyst for large-scale biosynthesis of citronellyl acetate, given its low-cost production, high activity at low temperatures, and reusability in a minimum of seven 24-h biocatalytic cycles.

Stimulatory Effects of Oleci Acid and Fungal Elicitor on Betulinic Acid Production by Submerged Cultivation of Medicinal Mushroom Inonotus obliquus.

To evaluate the novel strategy of oleic acid and fungal elicitor (made from Aspergillus niger) to elicit betulinic acid biosynthesis in medicinal mushroom Inonotus obliquus, we conduct the stimulatory effects investigation for synthesizing betulinic acid from betulin. HPLC results indicated oleic acid and fungal elicitor were effective stimulators. The supplementation of 1.0 g/L oleic acid led to the highest increase of betulinic acid either in dry mycelia or fermentation broth by 2-fold of the control. Fungal elicitor at 45 mg/L markedly increases mycelia growth by 146.0% and enhance intracellular betulinic acid accumulation by 429.5% as compared to the controls. Quantification of transcription levels determined that oleic acid, fungal elicitor and their combinations could induce the expressions of key genes involved in betulinic acid biosynthesis, such as HMG-CoA reductase and squalene synthase. These findings indicated that oleic acid and fungal elicitor could enhance betulinic acid metabolism by up-regulating key genes expression.

Penicillium chrysogenum polypeptide extract protects tobacco plants from tobacco mosaic virus infection through modulation of ABA biosynthesis and callose priming.

The polypeptide extract of the dry mycelium of Penicillium chrysogenum (PDMP) can protect tobacco plants from tobacco mosaic virus (TMV), although the mechanism underlying PDMP-mediated TMV resistance remains unknown. In our study, we analysed a potential mechanism via RNA sequencing (RNA-seq) and found that the abscisic acid (ABA) biosynthetic pathway and β-1,3-glucanase, a callose-degrading enzyme, might play an important role in PDMP-induced priming of resistance to TMV. To test our hypothesis, we successfully generated a Nicotiana benthamiana ABA biosynthesis mutant and evaluated the role of the ABA pathway in PDMP-induced callose deposition during resistance to TMV infection. Our results suggested that PDMP can induce callose priming to defend against TMV movement. PDMP inhibited TMV movement by increasing callose deposition around plasmodesmata, but this phenomenon did not occur in the ABA biosynthesis mutant; moreover, these effects of PDMP on callose deposition could be rescued by treatment with exogenous ABA. Our results suggested that callose deposition around plasmodesmata in wild-type plants is mainly responsible for the restriction of TMV movement during the PDMP-induced defensive response to TMV infection, and that ABA biosynthesis apparently plays a crucial role in PDMP-induced callose priming for enhancing defence against TMV.

Total Phenolic and Flavonoid Content, Antioxidant Activity of Talaromyces funiculosus Strains

Microscopic fungi synthesize a wide range of phenolic compounds that play an important role in cell wall formation, as well as perform signaling and protective functions. One of the important functions of phenolic compounds, primarily polyphenols, is antioxidant activity. The most active polyphenols are flavonoids, their synthesis in microscopic fungi has not been studied enough. The aim of the study was to determine the total phenols and flavonoids content and antioxidant activity of Talaromyces funiculosus strains isolated from different econiches. Methods. 20 strains of the microscopic fungus T. funiculosus – 10 endophytes and 10 saprotrophs were used in the experiments. Cultivation of filamentous fungi was performed under submerged conditions with shaking at 210–230 rpm in Erlenmeyer flasks containing 200 ml of Czapek liquid medium at a temperature 26±2°C for 6 days. The biomass of the strains was filtered, dried at 70°C and extracted with 95% methanol (1:50 w/v). The total phenols content was determined using Folin-Ciocalteu reagent by the method of Arora, Chandra (2010) with some modifications and expressed as mg of gallic acid equivalents (GAE) per g of dry weight mycelium. Flavonoids in each extract were determined spectrophotometrically with AlCl3 and expressed as mg of quercetin equivalents (QE) per g of dry weight mycelium. Antioxidant activity of methanolic extracts was measured as radical scavenging activity by the percentage inhibition of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. Results. The total phenolic content of methanolic extracts of T. funiculosus strains ranged from 0.12±0.007 to 1.97±0.150 mg GAE/g. The highest level of phenolic compounds was found for saprotroph UCM F-16790 (1.97±0.150) and endophyte UCM F-16795 (1.71±0.137 mg GAE/g). The flavonoid content in methanolic extracts of the studied strains varied in the range of 0.02±0.001–0.39±0.041 mg QE/g. All studied strains of T. funiculosus showed antioxidant activity against DPPH radical, which was 12.19±2.34–60.37±7.24% inhibition. Statistical analysis revealed a strong positive correlation between the total phenols and flavonoids content (Pearson’s correlation coefficient r=0.92); between antioxidant activity, phenols (r=0.82) and flavonoids (r=0.81) content in methanol extracts of T. funiculosus strains. The total content of phenols and flavonoids and antioxidant activity did not depend on the trophic group of the studied strains. The moderate correlation between flavonoids content and antioxidant activity of methanolic extracts of endophytic T. funiculosus strains (r=0.46) may be related to their ability to synthesize a wider range of polyphenolic compounds with antioxidant activity. Conclusions. The studied T. funiculosus strains have the ability to synthesize phenolic compounds and flavonoids in different concentrations. Correlation analysis revealed strong correlations between total phenolic and flavonoid contents and antioxidant activity. The reason for phenomenon of moderate correlation (r=0.46) between flavonoid content and antioxidant activity in endophytic strains may be the synthesis of other compounds by individual strains. The determination of individual components synthesized by the most active strains is of scientific interest for further study. T. funiculosus UСM F-16795 and UСM F-16790 strains had a quite high level of phenols and flavonoids. Obtained data may be promising for the search for phenolic compounds with antioxidant properties to increase plant resistance to negative impacts of environmental stress factors.

Effect of gamma radiation on fungal growth stages and mechanical properties of traditional Japanese paper

Abstract In this study, we investigated the effect of gamma irradiation on fungal growth and mechanical properties of the traditional Japanese paper, Kohzo-gami, infected by mesophilic fungi such as Aspergillus sydowii, Penicillium chrysogenum, and Cladosporium cladosporioides. The radiation sensitivities of dormant conidium-, germinating conidium-, and mycelium-contaminated wet and dry paper were also determined. A radiation dose capable of inactivating 50% of a 30-sample population was used for comparison. Our results showed that the 50% inactivation dose did not significantly differ between wet and dry dormant conidia. However, the survival percentage of dry dormant conidia was higher than that of wet dormant conidia at a high radiation dose. In contrast, the 50% inactivation doses for dry germinating conidia and dry mycelia were significantly lower than those for wet germinating conidia and wet mycelia, respectively. These results indicate that drought stress increased the radiation sensitivity of germinating conidia and mycelia. We also investigated the mechanical properties of Kohzo-gami irradiated at different doses. The order of the tensile strength of Kohzo-gami relative to that of control samples was as follows: 10 kGy > 30 kGy > 40 kGy. This result suggests that even a 10 kGy radiation dose can affect the mechanical properties of paper. The color change level of Kohzo-gami increased significantly at all doses; however, the National Bureau of Standards rating showed only “slight change” at all doses. The radiation doses required for fungal disinfection varied considerably depending on the fungal species and the total number of fungal cells on contaminated paper. Therefore, it was difficult to determine the standard exposure dose for treatment. However, paper sterilization might not be required, as a combination of low-dose radiation and dryness can effectively kill fungal mycelia on contaminated paper.