Ostreatus Strains Research Articles

Transcription factor Pofst3 regulates Pleurotus ostreatus development by targeting multiple biological pathways

Pleurotus ostreatus is a popular edible mushroom cultivated worldwide. However, the mechanism of P. ostreatus primordia formation is unclear. Pofst3 is a MHR superfamily transcription factor, which has the function of regulating primordia formation. In this study, the target genes of Pofst3 in P. ostreatus were identified by DAP-Seq approach at the genome level, 1481 peaks were obtained and the Pofst3 binding motif sequence was GARGRVGARGAR. The interaction between transcription factor Pofst3 and this motif was confirmed in vitro and in vivo through electrophoretic mobility shift (EMSA) and yeast one-hybrid screening (Y1H) assays. Among the top 20 GO enrichment results, most were related to transcriptional regulation, and some transcription factor encoding genes, such as HMG-box (gene_5346), MADS-box (gene_86), FOG (gene_6211) and RFX (gene_3496) were obtained. Besides basic metabolism, MAPK signaling pathway, Inositol phosphate metabolism, Glycosylphosphatidylinositol (GPI)-anchor biosynthesis and Pentose phosphate pathway were significantly enriched in the KEGG pathway analysis. The expression levels of randomly selected 11 genes, some transcription factor genes, and genes involved in metabolic pathways in wild and Pofst3 transgenic P. ostreatus strains indicated that target genes likely involved in the development of the P. ostreatus primordia. These results indicated that transcription factor Pofst3 ultimately negatively regulated the development of P. ostreatus primordia very likely through regulating a series of biological pathways.

The Influence of Substrate and Strain on Protein Quality of Pleurotus ostreatus

Background: The effect of substrate and strain on the nutritional and functional properties of mushroom flours and protein concentrates (PCs) has not thoroughly been investigated. Methods: The proteins of P. ostreatus flours (strains AMRL144 and 150) were isolated following alkaline extraction (pH 12) and isoelectric precipitation (pH 4) as it was determined by the solubility curves. The protein quality of the flours and PCs were evaluated by determining the protein solubility index (PSI) and their functional properties, such as water (WAC) and oil absorption capacity (OAC), foam capacity (FC), foam stability (FS) and emulsion stability (ES). The amino acid (AA) composition of the flours was determined by reversed-phase liquid chromatography after protein hydrolysis and o-phthalaldehyde derivatization. Results: The PSIs of the flours and PCs of P. ostreatus were comparable to those of soy protein flours and protein concentrates. The highest AA concentration was found for both strains when cultivated on the barley and oat straw (BOS) substrate, showing a similar trend as the protein content. A principal component analysis (PCA) indicated an impact of the strain on the functional properties. Conclusions: Both strains can produce high quality proteins especially when cultivated on wheat straw (WS). The FS was positively correlated with the P. ostreatus strain AMRL150 whereas the FC was positively correlated with AMRL144.

Differential analyses of morphology and transcription from oyster mushroom Pleurotus ostreatus response to brown blotch disease

Pleurotus ostreatus is among the most frequently cultivated and consumed mushrooms worldwide. However, brown blotch disease (BBD) caused by the pathogenic bacterium Pseudomonas tolaasii severely impacted its quality and production. In this study, we selected the BBD-resistant strain HP36 and the BBD-sensitive strain HP801 from twenty P. ostreatus strains. Obvious morphological and ultrastructural differences between the two strains were observed at 12 h, 24 h and 72 h after Ps. tolaasii infection. At 24 h, a large area of brown-yellow blotch appeared on the pileus of HP801 and with Ps. tolaasii almost completely overgrowing the pileus. In contrast, few bacteria and no obvious symptoms were found on the pileus of HP36. At 72 h, the cell wall and nuclei and mitochondria were seriously damaged in HP801 while no obvious deformity was observed in HP36. In the infected pileus, transcriptome analysis identified 153 and 2,189 differentially expressed genes for HP36 and HP801 respectively. Further bioinformatic analysis showed that genes encoding oxidation–reduction enzymes, cell wall degradation, heat shock proteins and protein kinases were significantly more differentially expressed after infection in HP801 than in HP36. The results suggested that Ps. tolaasii infection impaired the capacities of HP801 for stress sensing and signal transduction, oxidation resistance and protein modification, resulting in cellular and organelle damages. Together, our results provided insights into the molecular mechanism of resistance to BBD in P. ostreatus and suggested potential strategies for controlling BBD and improving mushroom production and quality by selecting and breeding the resistant strains.

Environmental implications of three Pleurotus strain growths for water remediation in the perspective of climate change in New Egyptian Delta

Recently, the integrated different interdisciplinary studies derived the environmental solutions of the climate change impacts (e.g., cultivation, wastewater treatment, and managing groundwater resources) (Mesalhy et al. 2020, and Gobashy et al. 2021). Thus, this paper focused on the application of bioremediation to maximize the use of wastewater for new reclamation areas in the Northwest Egyptian desert (New Egyptian Delta (NED). In the NED project, the drainage water samples collected from Nile Delta drains will provide the main unconventional water resources for irrigation through the new Hammam canal. Therefore, three Pleurotus strains were grown moderately on two natural media, the first containing Salvia L. (sage) extract (MDA) and the second containing Thymus vulgaris L. (origanum thymus Kuntze, Thymus collinus Salisb) (TDA) extract replacing potato infusions in standard PDA. Pleurotus ostreatus (Jacquin; Kummer) strain records the highest growth among the three tested fungi on modified media. PO records 4.49 and 4.41 cm on (MDA) and (TDA), respectively. There is a marked decrease in the majority of heavy metal concentrations on sterile drainage water amended with PD broth and inoculated with three tested Pleurotus strains individually. At the end of the incubation period, Pleurotus ostereatus which expressed in abbreviation (PO) are more efficient in the removal of Al, Co, Cr, and Ni by 53.15, 95.87, 58.47, and 85.07%; respectively. Pleurorotus pulmonarius (Fr.) which symbolized (PP) is more potent in the removal of Cd, Si, Sn, Sr, and V by 70.37, 56.59, 41.19, 52.78, and 96.24%; respectively. Pleurotus floridanus (NZOR) which indicated as (PF) is actively over the former species in the removal of Ba, Fe, and Mo by 87.84, 46.67, and 97.34%; respectively. Cu, Mn, Pb, As, and Se could not be detected as the control sample recorded measurements below 0.009 mg L−1. An unexpected increase in Zn among the different treatments was detected from 05.04 to 07.01%.

Strain-specific features of Pleurotus ostreatus growth in vitro and some of its biological activities

BackgroundThe production of Pleurotus ostreatus mycelium as a promising object for use in food and other industries is hampered by a lack of information about the strain-specificity of this fungus mycelium growth and its acquisition of various biological activities. Therefore, this research aimed to investigate mycelial growth of different P. ostreatus strains on varies solid and liquid media as well as to evaluate strains antagonistic, antibacterial, antiradical scavenging activities, and total phenolic content.ResultsPotato Dextrose Agar medium was suitable for all strains except P. ostreatus strain 2460. The best growth rate of P. ostreatus 2462 strain on solid culture media was 15.0 ± 0.8 mm/day, and mycelia best growth on liquid culture media—36.5 ± 0.2 g/l. P. ostreatus strains 551 and 1685 were more susceptible to positive effect of plant growth regulators Ivin, Methyur and Kamethur. Using of nutrient media based on combination of natural waste (amaranth flour cake and wheat germ, wheat bran, broken vermicelli and crumbs) has been increased the yield of P. ostreatus strains mycelium by 2.2–2.9 times compared to the control. All used P. ostreatus strains displayed strong antagonistic activity in co-cultivation with Aspergillus niger, Candida albicans, Issatchenkia orientalis, Fusarium poae, Microdochium nivale in dual-culture assay. P. ostreatus 2462 EtOAc mycelial extract good inhibited growth of Escherichia coli (17.0 ± 0.9 mm) while P. ostreatus 2460 suppressed Staphylococcus aureus growth (21.5 ± 0.5 mm) by agar well diffusion method. The highest radical scavenging effect displayed both mycelial extracts (EtOH and EtOAc) of P. ostreatus 1685 (61 and 56%) by DPPH assay as well as high phenolic content (7.17 and 6.73 mg GAE/g) by the Folin-Ciocalteu’s method. The maximal total phenol content (7.52 mg GAE/g) demonstrated of P. ostreatus 2461 EtOH extract.ConclusionsIt is found that the growth, antibacterial, antiradical scavenging activity as well as total phenolic content were dependent on studied P. ostreatus strains in contrast to antagonistic activity. The proposed culture mediums of natural waste could be an alternative to commercial mediums for the production mycelial biomass of P. ostreatus strains.

Visualizing organelles with recombinant fluorescent proteins in the white-rot fungus Pleurotus ostreatus

White-rot fungi secrete numerous enzymes involved in lignocellulose degradation. However, the secretory mechanisms or pathways, including protein synthesis, folding, modification, and traffic, have not been well studied. In the first place, few experimental tools for molecular cell biological studies have been developed. As the first step toward investigating the mechanisms underlying protein secretion, this study visualized organelles and transport vesicles involved in secretory mechanisms with fluorescent proteins in living cells of the white-rot fungus Pleurotus ostreatus (agaricomycete). To this end, each plasmid containing the expression cassette for fluorescent protein [enhanced green fluorescent protein (EGFP) or mCherry] fused with each protein that may be localized in the endoplasmic reticulum (ER), Golgi, or secretory vesicles (SVs) was introduced into P. ostreatus strain PC9. Fluorescent microscopic analyses of the obtained hygromycin-resistant transformants suggested that Sec13-EGFP and Sec24-EGFP visualize the ER; Sec24-EGFP, mCherry-Sed5, and mCherry-Rer1 visualize the compartment likely corresponding to early Golgi and/or the ER-Golgi intermediate compartment; EGFP/mCherry-pleckstrin homology (PH) visualizes possible late Golgi; and EGFP-Seg1 and mCherry-Rab11 visualize SVs. This study successfully visualized mitochondria and nuclei, thus providing useful tools for future molecular cell biological studies on lignocellulose degradation by P. ostreatus. Furthermore, some differences in the Golgi compartment or apparatus and the ER-Golgi intermediate of P. ostreatus compared to other fungi were also suggested.

Diversity and domestication of mushroom species in the Atewa forest reserve and Bia Biosphere, Ghana

Edible mushrooms commonly found in forest reserves are important for food security but they are underutilized in Ghana. The Atewa forest reserve in the Eastern Region and Bia Biosphere in the Western Region are among the largest forest reserves in Ghana. However, human activities including illegal mining activities pose a threat to the existence of the rich mushroom diversity within these forests. The objective of this study, therefore, was to collect, characterize and domesticate mushrooms from the Atewa forest reserve and the Bia Biosphere. Wild mushroom samples were randomly photographed, collected, dried and stored. Edible and wild mushrooms were characterized morphologically and compared with literature. A total of 86 mushroom samples (comprising 45 from the Atewa forest reserve and 41 from the Bia Biosphere) were collected and identified. The two forest reserves contained a rich diversity of wild mushrooms namely: Cookeina speciosa, Marasmiellua inoderma, Auricularia cornea, Daldina concentrica, Pleurotus sp. Polypores. Cultivated Auricularia auricula strain AUAT recorded the highest ash content (16.70%) while cultivated Ganoderma sp. strain GLB recorded the lowest ash content (5.12%). On the other hand, cultivated Pleurotus ostreatus strain POB recorded the highest fat content of 19.88% and cultivated Pleurotus saju-caju strain PSCAT gave the least value of 12.02%. Cultivated Auricularia auricula strain AUAT again recorded the highest protein value of 33.38% while wild Ganoderma sp. Strain GLB had the least protein value. A total carbohydrate level of 64.22% was observed in cultivated Ganderma sp. strain GLB. The highest oxalate content of 30.93 mg/100 g was recorded in cultivated Pleurotus ostreatus strain EM1 with cultivated Auricularia auricula strain AUAT being the least value of 4.73 mg. A high phytate value of 149.35 mg was observed in cultivated Auricularia auricula strain AUAT and cultivated Pleurotus saju-caju strain PLAT showed the lowest value of 31.60 mg/100 g. The present findings provide considerable data on fungal diversification, conservation and domestication as well as a reference point for future studies.

Molecular characterization of a novel deltaflexivirus infecting the edible fungus Pleurotus ostreatus.

A novel positive single-stranded RNA virus, Pleurotus ostreatus deltaflexivirus 1 (PoDFV1), was isolated from the edible fungus Pleurotus ostreatus strain ZP6. The complete genome of PoDFV1 is 7706 nucleotides (nt) long and contains a short poly(A) tail. PoDFV1 was predicted to contain one large open reading frame (ORF1) and three small downstream ORFs (ORFs 2-4). ORF1 encodes a putative replication-associated polyprotein of 1979 amino acids (aa) containing three conserved domains - viral RNA methyltransferase (Mtr), viral RNA helicase (Hel), and RNA-dependent RNA polymerase (RdRp) - which are common to all deltaflexiviruses. ORFs 2-4 encode three small hypothetical proteins (15-20 kDa) without conserved domains or known biological functions. Sequence alignments and phylogenetic analysis suggested that PoDFV1 is a member of a new species in the genus Deltaflexivirus (family Deltaflexiviridae, order Tymovirales). To our knowledge, this is the first report of a deltaflexivirus infecting P. ostreatus.

Multiplex Detection of Pleurotus ostreatus Mycoviruses

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.

Growth of different strains of Pleurotus ostreatus in lignocellulosic biomasses

Agro-industrial waste has been widely applied in bioprocesses, among which fungiculture has been highlighted for its ability to transform waste into value-added products. Thus, this study observed two strains (474 and 572) of Pleurotus ostreatus when cultivated in residues of pineapple crown, açaí seeds and mixture of pineapple crowns and açaí seeds, and evaluated the colonization of the substrates, formation of structures and quantity of mushrooms produced. In all the substrates, it was possible to observe complete colonization, with the emergence of primordia up to 20 days. In the treatments with the 474 strain, only in the pineapple crown substrate were there three flushes of production, while in the açaí seeds and pineapple crowns and açaí seeds, there were only two flushes. As for strain 542, all treatments showed three flushes. The pineapple crown substrate provided greater production of basidiocarps (fresh mass) in strains 474 and 542. Therefore, the capacity of adaptation and development of P. ostreatus strains in different substrates was evidenced, since mushrooms were produced with characteristics similar to those reported in the literature.

Physico-chemical characterization of lignocellulosic wastes used in the cultivation of Pleurotus ostreatus

The choice of residue to be used in the cultivation of a fungal species must take into account the structural and chemical composition of the material in order to be successful in their cultivation. Thus, this study evaluated the physical and chemical characteristics of pineapple and açaí residues and their alterations after the cultivation of two Pleurotus ostreatus strains (474 and 542). The fungi were cultivated in pineapple, açaí, and pineapple + açaí residues, which were added to a mixture of brans, and CaCO3 in the proportion of 78:20:2 w/w/w. The physical and chemical parameters and proximate composition of the residues, and the initial and spent substrates were determined, in addition to being analyzed using scanning electron microscopy and X-ray diffraction. In general, among the residues tested, the pineapple substrate showed more interesting nutritional characteristics for fungiculture, as well as structural conformation and greater availability of nutrients. The açaí substrate was not suitable for fungal cultivation due to its structural characteristics and high tannin content. In this sense, knowing the characteristics of the material used as a support for mushroom growth is of paramount importance in order to achieve successful cultivation.

COMPARATIVE CHARACTERISTICS OF AROMA PROFILE OF WILD AND CULTURED EDIBLE MUSHROOMS

The increased consumption of edible mushrooms is not only due to their nutritional value, but also to their unique taste and specific flavor. The aroma of cultivated mushrooms is different from wild ones, it is often less pronounced. The aim of the study was to determine the characteristics of the aroma of wild and cultivated edible mushrooms using the methods of sensory profile analysis and ultraviolet spectrophotometry. Sensory profile analysis showed that aroma profiles of mushroom samples differed in intensity depending on a kind of a mushroom. It was found that Boletus sp. had the highest intensity of the mushroom component of flavor among wild mushrooms. The intensity of woody flavor components was higher in B. subtomentosus, L. aurantiacum and P. ostreatus IBK-1535. More pronounced herbaceous notes were observed for a wild P. ostreatus and A. silvaticus, sweet – for S. luteus, and floral – for P. djamor. Among the cultivated fungi, the most pronounced mushroom notes are observed for A. bisporus. The lowest intensity of aroma had such wild mushrooms as P. ostreatus and S. luteus. Also, the least pronounced flavor was noted for the cultivated P. djamor. The flavor of this mushroom is characterized by fishy notes. The obtained UV-spectra of different mushroom species varied in the intensity of the light absorption maxima. The highest intensity in the entire wavelength range had the extract of B. edulis fruit bodies. Among the cultivated fungi, A. bisporus was characterized by the highest optical density of hexane extract at 207 nm, and A. bisporus and P. ostreatus strains IBK-551 and IBK-1535 absorbed light the most intense in the region of 260–290 nm. The results of determining the organoleptic profile and spectrophotometric analysis of mushroom extracts indicate that the industrial cultivation of edible mushrooms disrupts or inhibits the formation of aroma substances by fruiting bodies, which leads to a decrease in their consumer quality. Therefore, in order to increase the demand for cultivated edible mushrooms, the flavor of which is one of the determining factors of their attractiveness, it is necessary to conduct a comprehensive study of the dependence of the aroma substances formation on the growing process parameters.

LC/MS Q-TOF Metabolomic Investigation of Amino Acids and Dipeptides in Pleurotus ostreatus Grown on Different Substrates.

The well-established correlation between diet and health arouses great interest in seeking new health-promoting functional foods that may contribute to improving health and well-being. Herein, the metabolomic investigation of Pleurotus ostreatus samples grown on two different substrates (black poplar wood logs, WS, and lignocellulosic byproducts, LcS) revealed the high potential of such a mushroom as a source of bioactive species. The liquid chromatography/mass spectrometry combined with quadrupole time-of-flight (LC/MS Q-TOF) analysis allowed the identification of essential and nonessential amino acids along with the outstanding presence of dipeptides. Multivariate statistical models highlighted important differences in the expression of both classes of compounds arising from the growth of P. ostreatus strains on WS and LcS. The former, in particular, was correlated to an increased expression of carnitine-based amino acid derivatives and proline-based dipeptides. This finding may represent a potential strategy to drive the expression of bioactive compounds of interest to obtain enriched mushrooms or useful functional ingredients from them.

Preliminary Studies on the Effects of Oyster Mushroom Spherical Virus China Strain on the Mycelial Growth and Fruiting Body Yield of the Edible Mushroom Pleurotus ostreatus.

Simple SummaryOyster mushroom spherical virus (OMSV) is a positive-sense single-stranded RNA mycovirus which is associated with a devastating oyster mushroom die-back disease. However, little is known about its classification, and the effects of OMSV infection on its fungal host remain unclear. In the present study, we present the molecular evidence that virus isolates from the P. ostreatus 8129 strain in China represent a new strain of OMSV, named OMSV-Ch. Phylogenetic analysis based on the putative replication protein (RP) suggest that the OMSV may belong to a new yet-to-be-established genus of the Tymoviridae. Using single hyphal tip cultures combined with high-temperature treatment, we obtained the OMSV-Ch-cured P. ostreatus strain. Preliminary studies indicate that OMSV-Ch infection can significantly inhibit mycelial growth, cause malformation symptoms, and reduce the yield of the fruiting bodies of the edible mushroom P. ostreatus. Furthermore, OMSV-Ch can horizontally transfer to a virus-cured strain.Oyster mushroom spherical virus (OMSV) is a positive-sense single-stranded RNA mycovirus which is associated with a devastating oyster mushroom die-back disease. However, little is known about its diversity, and the effects of OMSV infection on its fungal host are not well understood. In this study, we determined the nearly complete nucleotide sequence of OMSV isolated from cultivated oyster mushrooms in China. Sequence analysis suggested that the virus represents a new strain of OMSV (referred to here as OMSV-Ch). A GenBank BLAST search of the genomic sequences demonstrated that the OMSV-Ch had the highest identity (74.9%) with the OMSV from Korea (OMSV-Kr). At the amino acid–sequence level, these two strains shared 84.1% identity in putative replication protein (RP) and 94.1% identity in coat protein (CP). Phylogenetic analysis based on RP showed that OMSV-Ch clustered with OMSV-Kr, closely related to Tymoviridae. Phylogenetic analysis based on both the RP and CP showed that OMSV had a distant clade relationship with tymoviruses, marafiviruses, and maculaviruses. We obtained the OMSV-Ch-free Pleurotus ostreatus strain via single hyphal tip cultures combined with high-temperature treatment. Preliminary studies indicate that OMSV-Ch can significantly inhibit mycelial growth, cause malformations of the fruiting bodies, and reduce the yield of P. ostreatus. Co-cultivation resulted in horizontal transmission of the OMSV-Ch to a virus-cured strain. The findings of our study contribute to the prevention and control of mycoviral diseases in the future.

Cultivating Pleurotus ostreatus and Pleurotus eryngii mushroom strains on agro-industrial residues in solid-state fermentation. Part II: Effect on productivity and quality of carposomes

The potential of selected Pleurotus ostreatus and P. eryngii wild-type and commercial strains to colonize and produce carposomes after solid-state fermentation of five substrates constituted of agro-residues namely wheat straw (WS), beech wood shavings (BWS), coffee residue (CR), barley and oats straw (BOS), rice bark (RB), supplemented with wheat bran was investigated. The effect of substrate composition on bioprocess feasibility was assessed for the different strains by quantitative (i.e., mushroom yield and Biological Efficiency-BE %) and carposome qualitative parameters (i.e., weight, size, colour, firmness). P. ostreatus strains produced carposomes earlier than P. eryngii ones. Early fruiting formation was promoted in WS for P. ostreatus strains, whereas for P. eryngii the lowest values of earliness were observed on BOS substrate. As for crop productivity, P. ostreatus strain AMRL 150 provided the highest BE (>70%) in all substrates except for RB, while P. ostreatus strain AMRL 144 achieved the highest yield and BE in BOS and BWS (75.30 and 64.26%, respectively). P. eryngii stains produced less number but heavier carposomes. The highest values of BE% for these strains were recorded on WS and BOS substrates. The BE was further correlated to growth parameters of fungal vegetative phase. As for mushroom colour, P. ostreatus were lighter than P. eryngii and BOS substrate promoted lightness in both strains. Firmer P. ostreatus mushrooms were produced at CR. No differences in the whiteness and firmness were detected among P. eryngii mushrooms and at any substrate used. The data included in this paper showed that Pleurotus mushrooms can be cultivated on low- or zero-value agro-industrial residues of great financial and environmental importance towards the production of value-added food products.

Cultivating Pleurotus ostreatus and Pleurotus eryngii mushroom strains on agro-industrial residues in solid-state fermentation. Part I: Screening for growth, endoglucanase, laccase and biomass production in the colonization phase

The influence of ten agro-residues, i.e., wheat straw (WS), poplar wood sawdust (PWS), grape pomace (GP), beech wood shavings (BWS), cotton cake (CK), corn cobs (CC), coffee residue (CR), olive pulp (OP), barley and oats straw (BOS) and rice bark (RB), used as alternative substrates for the cultivation of Pleurotus mushrooms, was examined during mycelial growth (colonization phase). Several native and commercial strains of P. ostreatus and P. eryngii were subjected to screening regarding their mycelial growth rates, biomass production and endoglucanase and laccase activities. The experimental results showed that the highest growth rates of P. ostreatus strains were noticed on BWS, BOS, CC and RB substrates, with the time of complete colonization varying between 16 and 36 days, whereas for P. eryngii a high linear growth rate was observed on CC, OP, CR and BOS with the colonization period ranging between 26 and 51 days. The maximum biomass production obtained on the various substrates for both Pleurotus species ranged from 115.32 to 454.42 mg/g d.w. for P. ostreatus and from 108.50 to 422.59 mg/g d.w. for P. eryngii. As for endoglucanase, the highest activities were observed in P. eryngii AMRL 163 cultures on PWS and BOS, i.e., 0.19 and 0.18 U/g d.w., respectively. P. eryngii AMRL 173–6 and P. ostreatus AMRL 150 cultivated on RB and BOS, synthesized significant laccase amounts, i.e., 2172.28 and 1987.25 U/g d.w., respectively. The effect of the substrate components on the growth parameters was considered and discussed. This study showed the industrial potential to convert important low-value agro-residues to fungal biomass and enzymes and eventually to valuable food products.

The effect of carbon dioxide on the quality of the mushrooms

Mushrooms' quality may be significantly changing depending on their type, strain, growing cycle, packing, cooling, postharvest handling (PHH), and conditions of storage. This work aimed to define the influence of the type and mushrooms' strain, the regime of the PHH by carbon dioxide on their preservation (marketability, loss of weight (LW)), changes in the chemical substances, and physiological activity (intensity respiration (IR) and heat release (HR)). Mushrooms Agaricus bisporus (AB) (strains ІБК-25 and ІБК-15) and Pleurotus ostreatus (PO) (strains НК-35 and Amycel 3000) were used for testing. Three regimes of treatment by CO2 with a concentration of 20% were applied: 2 h; 12 h and 22 h. The control was the mushrooms without treatment by CO2. Changes in the chemical substances such as dry matters (DM), protein nitrogen (PN), and ascorbic acid (AA) in the researched mushrooms were observed. The best result of mushroom preservation was provided by the regime of CO2 treatment during 12 h. The yield of marketable AB was 94.9% (IBK-25) and 94.2% (IBK-15) comparison to control 93.5%, and 92.5%, respectively. The regime of PHH 2 h almost has no influence but 22 h harmed this indicator. PHH of mushrooms by carbon dioxide was promoted to preserve the DM and increasing concentration of CO2 was supplied better results. Thus, DM at the end of storage in the AB of strain IBK-25 depend on the regime were 8.5, 8.6, and 8.4%, against – 8.3% in the control variant. Significant quantitative changes in the PN and AA as a result of treatment by CO2 were not established. PHH also affected the IR and HR. The increased duration of treatment by CO2 inhibited the intensity of physiological processes in the mushrooms. But, as in previous cases, the best result was provided PHH by 20% CO2 during 12 h. Similar trends of treatments effect by carbon dioxide were observed in the mushrooms of PO.

Laccase activity from Pleurotus ostreatus and Flammulina velutipes strains grown on agro- and forestry residues by solid-state fermentation

Laccase activity from Pleurotus ostreatus and Flammulina velutipes strains was investigated with various agro- and forestry residues by solid-state fermentation. Different species or strains belonging to the same species had the unique capacity of secreting laccase on solid-state fermentation with various agro- and forestry residues. Overall, the capacity of secreting laccase for P. ostreatus strains was superior to F. velutipes strains due to the value of maximum activity on various agro- and forestry residues, except on the stalk of straw. Compared with Populus beijingensis, corncob, and stalk of straw, the presence of cottonseed hull was helpful to improve laccase activity for P. ostreatus strains because the maximum laccase activity from cottonseed hull was higher than that from the other three agro- and forestry residues. The presence of stalk of straw was more helpful to improve laccase activity for F. velutipes strains because of the maximum laccase activity from stalk of straw was higher that from Populus beijingensis, corncob, and cottonseed hull. These results indicated the importance of selecting suitable agro- and forestry residues for fungi producing laccase. These findings contributed to the selection of suitable strains to obtain an integrated application of low-cost laccase in the factory.

Functional analyses of Pleurotus ostreatus pcc1 and clp1 using CRISPR/Cas9

Understanding the molecular mechanisms controlling dikaryon formation in Agaricomycetes, which is basically controlled by A and B mating-type loci, contributes to improving mushroom cultivation and breeding. In Coprinopsis cinerea, various mutations in the SRY-type high mobility group protein-encoding gene, pcc1, were shown to activate the A-regulated pathway to induce pseudoclamp (clamp cells without clamp connection) and fruiting body formation in monokaryons. The formation of clamp cells was blocked in AmutBmut strain 326 with clp1-1 mutation in C. cinerea. However, considering the diverse mechanisms of sexual development among Agaricomycetes, it remains unclear whether similar phenotypes are also observed in clp1 or pcc1 mutants in cultivated mushrooms. Therefore, phenotypic analyses of Pleurotus ostreatus pcc1 or clp1 (Popcc1 or Poclp1) mutants generated using CRISPR/Cas9 were performed in this study. Plasmids with Cas9 expression cassette and different single guide RNAs targeting Popcc1 or Poclp1 were individually introduced into a monokaryotic P. ostreatus strain PC9 to obtain the mutants. Unlike in C. cinerea, the pseudoclamp cell was not observed in monokaryotic Popcc1 mutants, but it was observed after crossing two compatible strains with Popcc1 mutations. In Poclp1 mutants, dikaryosis was impaired as clamp cells were not observed after crossing, suggesting that Poclp1 functions may be essential for clamp cell formation, like in C. cinerea. These results provided a clue with respect to conserved and diverse mechanisms underlying sexual development in Agaricomycetes (at least between C. cinerea and P. ostreatus).

Genetic diversity of Pleurotus ostreatus (Jacq.) P. Kumm. strains in Java based on random amplified polymorphic DNA markers

Abstract. Ekowati N, Mumpuni A, Muljowati JS, Ratnaningtyas NI, Maharning AR. 2021. Genetic diversity of Pleurotus ostreatus (Jacq.) P. Kumm. strains in Java based on Random Amplified Polymorphic DNA markers. Biodiversitas 22: 3488-3493. Genetic variation in a fungal population can occur due to mutation and recombination, resulting in changes in the nucleotides that encode specific DNA sequences. Strains with a high genetic distance and good production capabilities can be used to develop genetic breeding. This study aimed to investigate genetic relationship among Pleurotus ostreatus strains cultivated in Java (Bogor, Cianjur, Tasikmalaya, Purwokerto, Yogyakarta, Tawangmangu, Malang, and Madiun) based on random amplified polymorphic DNA (RAPD) markers. The research method consisted of DNA isolation and DNA amplification using six primers, i.e. OPA2, OPA3, OPA4, OPA7, OPA9, and OPA10. DNA band data were analyzed using NTSYSpc21 software to determine the level of genetic similarity, based on the Unweighted Pair Group Method with Arithmetic Average Algorithm (UPGMA). In all, 101 amplified DNA bands were obtained, with sizes ranging from 136 to 2320 bp and 96.0% of the bands were polymorphic. Based on cluster analysis, it shows that three clusters were formed. There were genetic variations and relationships among eight P. ostreatus strains in Java with a genetic similarity varying from 37-98%.