The manganese peroxidase gene family (mnps) is a part of the ligninolytic system of Pleurotus ostreatus. This gene family is comprised of nine members, mnp1-9, encoding short manganese peroxidases ...(short-MnPs) or versatile peroxidases (VPs). We show that unlike in Mn super(2+)-amended glucose-peptone (GP) medium, where redundancy among mnps was reported, in Mn super(2+)-deficient GP medium mnp4 encoding versatile peroxidase isoenzyme 4 (VP4) has a key and nonredundant function. The abundance of mnps transcripts at time points corresponding to the tropophase (active growth), early idiophase, and idiophase indicates that mnp4 is the predominantly expressed mnp gene and that its relative predominance is dependent on the age of the culture. In this medium, azo dye, Orange II (OII) decolorization occurs only during the idiophase and a Delta mnp4 strain showed a drastic reduction in this decolorization. Three degradation metabolites were identified by liquid chromatography-mass spectroscopy (LC-MS), indicating both asymmetric and symmetric enzymatic cleavage of the azo-bond. In addition, the culture filtrate of Delta mnp4 showed negligible values of oxidation capability of four typical VP substrates: Mn super(2+), 2,6-dimethoxyphenol, phenol red, and Reactive Black 5 (RB5), compared to the wild-type strain PC9. We concluded that under Mn super(2+)-deficient GP culture, VP4 (encoded by mnp4) is the main active ligninolytic enzyme able to oxidize Mn super(2+) as well as high and low redox potential aromatic substrate, including dyes. Furthermore, other VPs/MnPs do not compensate for the lack of VP4 activity.
Mycelium-based composites result from the growth of filamentous fungi on organic materials such as agricultural waste streams. These novel biomaterials represent a promising alternative for product ...design and manufacturing both in terms of sustainable manufacturing processes and circular lifespan. This study shows that their morphology, density, tensile and flexural strength, as well as their moisture- and water-uptake properties can be tuned by varying type of substrate (straw, sawdust, cotton), fungal species (Pleurotus ostreatus vs. Trametes multicolor) and processing technique (no pressing or cold or heat pressing). The fungal species impacts colonization level and the thickness of the air-exposed mycelium called fungal skin. Colonization level and skin thickness as well as the type of substrate determine the stiffness and water resistance of the materials. Moreover, it is shown that heat pressing improves homogeneity, strength and stiffness of the materials shifting their performance from foam-like to cork- and wood-like. Together, these results demonstrate that by changing the fabrication process, differences in performance of mycelium materials can be achieved. This highlights the possibility to produce a range of mycelium-based composites. In fact, it is the first time mycelium composites have been described with natural material properties.
Display omitted
•The type of fungus influences homogeneity of mycelium composite materials and thickness of the fungal skin.•The fungal skin impacts mechanical behaviour of the mycelium composite material and improves water resistance.•Straw-based materials are stiffer and less moisture-resistant than cotton-based mycelium composites.•Heat pressing improves homogeneity, strength and stiffness of mycelium composite material.•Heat-pressed mycelium materials have similar density and elastic modulus as natural materials (e.g. cork and wood).
In this work, the production of fungal laccase was optimized from local isolate of
using solid state fermentation
Factorial design was used to study the effect of several nutrients on enzyme ...production. Purification and characterization of the enzyme and the effect of temperature, pH and gamma radiation on fungal growth and enzyme production was investigated. Optimization of production conditions yielded an enzyme with activity over 32,450 IU/g of fermented substrate. Factorial design was capable of establishing the conditions that multiplied the activity of the enzyme several folds, consequently, reducing the cost of production. The enzyme was capable of decolorizing several dyes with over 80% reduction in color confirming the aromatic degrading capability of laccase. The enzyme was also used in the synthesis of gold nanoparticles, proving that laccase from
has a strong potential in several industrial applications.
This study investigates P. ostreatus and A. bisporus biodegradation capacity of low density polyethylene (LDPE) oxidised to simulate environmental weathering. Fourier transform infrared (FT-IR) ...spectroscopy and scanning electron microscopy (SEM) were used to analyse the degradation of LDPE treated with fungal cultures. Molecular implications of LDPE degradation by P. ostreatus and A. bisporus were evaluated by Reverse transcription followed by quantitative PCR (qRT-PCR) of lac, mnp and lip genes expression. After 90 days of incubation, FT-IR analysis showed, for both fungal treatments, an increasing in the intensity of peaks related to the asymmetric C-C-O stretching (1160 to 1000 cm−1) and the -OH stretching (3700 to 3200 cm−1) due to the formation of alcohols and carboxylic acid, indicating depolymerisation of LDPE. This was confirmed by the SEM analysis, where a widespread alteration of the surface morphology was observed for treated LDPE fragments. Results revealed that the exposure of P. ostreatus to oxidised LDPE treatment led to a significant increase in the expression of the lac6, lac7, lac9, lac10 and mnp2 genes, while A. bisporus showed an over-expression in lac2 and lac12 genes. The obtained results offer new perspectives for a biotechnological use of P. ostreatus and A. bisporus for plastic bioremediation.
Display omitted
•LDPE biodegradation occurs when inoculated with P. ostreatus and A. bisporus.•Both fungal treatments induced shifts in LDPE functional groups.•A significant morphological alteration of LDPE was observed after fungal treatments.•The over-expression of Lac and Mnp isoenzymes was assessed for P. ostreatus.•The over-expression of Lac isoenzymes was assessed for A. bisporus.
Mycoviruses are viruses that specifically infect and replicate in fungi. Several mycoviruses have been previously reported in Pleurotus ostreatus, including the oyster mushroom spherical virus ...(OMSV), oyster mushroom isometric virus (OMIV), Pleurotus ostreatus spherical virus (POSV), and Pleurotus ostreatus virus 1 (PoV1). This study was designed to develop a multiplex RT-PCR for simultaneous detection and differentiation of the four P. ostreatus mycoviruses. Four pairs of primers were designed from conserved regions based on the reported sequences and the multiplex RT-PCR products were 672 bp for OMSV, 540 bp for OMIV, 310 bp for POSV, and 200 bp for PoV1. The optimal annealing temperature of the multiplex RT-PCR was 62 °C and the detection limits of the plasmids were 100 fg for OMSV and OMIV and 1 pg for POSV and PoV1. This technique was successfully applied for the detection of OMSV, OMIV, and POSV from different P. ostreatus strains and the plasmid containing the PoV1 sequence. This methodology can serve as a powerful diagnostic tool for the survey of the incidence and epidemiology of the four P. ostreatus mycoviruses, further contributing to the prevention and treatment of mycoviral diseases in P. ostreatus.
Pleurotus ostreatus is one of the most cultivated edible fungi worldwide, but its lignocellulose utilization efficiency is relatively low (<50 %), which eventually affects the biological efficiency ...of P. ostreatus. Improving cellulase production and activity will contribute to enhancing the lignocellulose-degrading capacity of P. ostreatus. AMP-activated/Snf1 protein kinase plays important roles in regulating carbon and energy metabolism. The Snf1 homolog (PoSnf1) in P. ostreatus was obtained and analyzed using bioinformatics. The cellulose response of PoSnf1, the effect of the phosphorylation level of PoSnf1 on the expression of cellulose degradation-related genes, the putative proteins that interact with the phosphorylated PoSnf1 (P-PoSnf1), the cellobiose transport function of two sugar transporters (STP1 and STP2), and the interactions between PoSnf1 and STP1/STP2 were studied in this research. We found that cellulose treatment improved the phosphorylation level of PoSnf1, which further affected cellulase activity and the expression of most cellulose degradation-related genes. A total of 1, 024 proteins putatively interacting with P-PoSnf1 were identified, and they were enriched mainly in the substances transport and metabolism. Most of the putative cellulose degradation-related protein-coding genes could respond to cellulose. Among the P-PoSnf1-interacting proteins, the functions of two sugar transporters (STP1 and STP2) were further studied, and the results showed that both could transport cellobiose and were indirectly regulated by P-PoSnf1, and that STP2 could directly interact with PoSnf1. The results of this study indicated that PoSnf1 plays an important role in regulating the expression of cellulose degradation genes possibly by affecting cellobiose transport.
•Cellulose treatment promoted the phosphorylation of PoSnf1.•The phosphorylated PoSnf1 (P-PoSnf1) could interact with and indirectly regulated the expression of the cellulose degrading-related proteins.•Sugar transporters STP1 and STP2 could respond to cellulose and transport cellobiose.•The expression of both STP1 and STP2 were upregulated by P-PoSnf1, and STP2 could interact with PoSnf1.
Pleurotus ostreatus has potent antimicrobial properties. In this study, bioactive compounds were extracted from P. ostreatus and screened against bacterial and fungal phytopathogens. In terms of the ...antibacterial activity, the n-hexane extract of P. ostreatuse exhibited a significant inhibition zone of 88.55 mm against Xanthomonas axonopodis, while the highest antifungal activity of 83% was against Fusarium oxysporum. It was observed that the highest level of concentrations, i.e., 25 mg mL−1, caused a 76, 82, 82, 83, and 60% decrease in fungal biomass over the control against the fungal strains, i.e., A. alternata, A. flavus, D. australiensis, F. oxysporum and M. phaseolina, respectively. GC-MS analysis was performed on the n-hexane extract depicting the presence of 26 compounds. A compound identified as Toluene (Molecular weight = 92) exhibited a peak area of 91% followed by another compound named Cyclopentane, methyl- (Molecular weight = 84) showing a peak area of 56%. A well-known antimicrobial compound Aziridine (Mol. Weight = 99) was identified and showed a maximum hit of 84%, with a peak area of 56%. P. ostreatus could be a potent biocontrol antagonist against the plant pathogens.
Oat protein isolate is nutritious but with poor processing functionality. Pleurotus ostreatus β-glucan with good processing functionality can be conjugated with oat protein isolate via Maillard ...reaction, leading to an improved utilization of protein in food industry. Therefore, we produced conjugate with oat protein isolate and Pleurotus ostreatus β-glucan via Maillard reaction under controlled dry-heating conditions. The formation of conjugates with high molecular weight was identified by a new band of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The analysis of amino acid composition showed that cysteine and lysine were the dominant Maillard reaction sites of oat protein isolate and Pleurotus ostreatus β-glucan. Changes in spatial configuration of conjugates caused reduction in their surface hydrophobicity of proteins and intrinsic fluorescence intensity. Fourier transform infrared spectroscopy analysis of conjugates suggested that Maillard reaction could cause the C=O stretching vibration, as well as the C-H and N-H deformation vibration. Circular dichroism analysis indicated that the secondary structure of conjugates was altered by decreasing the contents of α-helix and β-sheet and increasing the contents of β-turn and random coil. The surface structure of conjugates was loose and porous using scanning electron microscope. Furthermore, Maillard reaction could improve the solubility, emulsifying property and thermal stability of oat protein isolate. Our findings confirm the potential of protein-carbohydrate conjugate formed by Maillard reaction, to improve the application of instable but valuable proteins in food industry.
Display omitted
•Oat protein isolate-Pleurotus ostreatus β-glucan conjugates with high grafting degree were prepared by Maillard reaction.•Structural changes of glycosylated oat protein isolate improved its solubility, emulsibility and thermostability.•Maillard reaction could enhance the utilization of oat protein isolate in food industry under controlled conditions.
Accurate 3D printing of thermo-responsive gel inks is a great challenge as the sol-gel transition and rheological properties change during extrusion are not easy to precisely regulate with 3D ...printing behavior has not been sufficiently studied. The effect of Pleurotus ostreatus protein (POP) correlated with the rheological properties and thermo-responsive behavior of the system on 3D printing performance of the thermo-responsive gel, namely κ-carrageenan (KG). Afterwards, their interaction mechanism was further clarified and final printed samples were evaluated in terms of antioxidant performance. Results indicated that POP addition increased the gelatinization temperature (Tg), significantly affecting the selection of optimum printing temperature. POP addition also improved viscosity and consistency index (K) of the printing ink, ultimately affecting the extrusion behavior. Temperature recovery property was facilitated by POP incorporation and was critical to the formability during recovery stage in 3D printing. Mechanical strength was improved with POP addition, which played an important role for the printed structures to be self-supportive. A lower concentration of POP (10%∼40%) was dispersed in a continuous KG-rich gel network and visible phase separation occurred when POP level was increased to 50%. Molecular interaction analysis showed that electrostatic interactions, hydrophobic interactions, ion on the correlation between the rheological properties and thermo-responsive behavior of gum-based 3D printing ink. In addition, POP presented a certain antioxidant activity. This study not only provided useful information on the correlation between the rheological and thermo-responsive behavior of gum-based 3D printing ink, but also provided a way to regulate 3D printing behavior of gum-based gel by protein incorporation. Moreover, it also showed the way to improve the nutritional value of the 3D printed sample.
Display omitted
•3D printing behavior was correlated with thermo-responsive and rheology properties.•3D printed KG based gel rich in protein was created.•The interactive mechanism between POP and KG was investigated.
In this study, total saponins were extracted from Pleurotus ostreatus cultivated with Astragalus as one of organic culture substrates. High Performance Thin Layer Chromatography (HPTLC) assay showed ...total saponins could be separated effectively, and four kinds of spots were identified as AG I, AG II, AG III, and AG IV, respectively. FTIR spectra based on HPTLC separation assay showed the saponin characteristic groups including ‐OH, C‐H, C=O, and the glycoside linkaged to sapogenin group C‐O‐C, suggesting the four kinds of spots belonged to cycloartane‐type triterpene saponins. The primary mass spectra of precursor ion (HPTLC‐ESI‐MS) assay further proved the main composition of four kinds of spots was AG I‐IV, respectively. Physical properties, including the detection of specific rotation and melting point, revealed the separation of high‐purity saponin monomer by HPTLC. HPTLC‐dual wavelength spectrodensitometric method detection showed that content of astragaloside I‐IV was ranged from 0.2 to 0.5 mg/g, and the total astragalosides contents attained to 1.397 mg/g, indicating P. ostreatus could bioaccumulate astragalosides from Astragalus. These results demonstrated the characterization of astragalosides based on the separation of HPTLC was effective, and supported to consider astragalosides‐enriched P. ostreatus as functional edible fungus for food and medical applications.
Practical Application
Currently, the consumption of enriched foods has become common and continues to increase due to urgent demanding for foods with high nutritional value. Pleurotus ostreatus is a functional edible fungus, which not only can produce secondary metabolites, but can enrich bioactive ingredients. Astragalosides have a wide range of biological activities, especially currently being tested as cardioprotective agent. In this study, P. ostreatus was cultivated through adding Astragalus into culture substrates, which realized massive enrichment of astragalosides. Astragalosides‐enriched P. ostreatus as functional edible fungus could be extensively used in food and medical areas, especially for the prevention of cardiovascular diseases.
PDF
