Regulation of dye-decolorizing peroxidase gene expression in Pleurotus ostreatus grown on glycerol as the carbon source.

Dye-decolorizing peroxidases (DyPs) (E.C. 1.11.1.19) are heme peroxidases that catalyze oxygen transfer reactions similarly to oxygenases. DyPs utilize hydrogen peroxide (H2O2) both as an electron acceptor co-substrate and as an electron donor when oxidized to their respective radicals. The production of both DyPs and lignin-modifying enzymes (LMEs) is regulated by the carbon source, although less readily metabolizable carbon sources do improve LME production. The present study analyzed the effect of glycerol on Pleurotus ostreatus growth, total DyP activity, and the expression of three Pleos-dyp genes (Pleos-dyp1, Pleos-dyp2 and Pleos-dyp4), via real-time RT-qPCR, monitoring the time course of P. ostreatus cultures supplemented with either glycerol or glucose and Acetyl Yellow G (AYG) dye. The results obtained indicate that glycerol negatively affects P. ostreatus growth, giving a biomass production of 5.31 and 5.62 g/L with respective growth rates (micra; m) of 0.027 and 0.023 h-1 for fermentations in the absence and presence of AYG dye. In contrast, respective biomass production levels of 7.09 and 7.20 g/L and growth rates (µ) of 0.033 and 0.047 h-1 were observed in equivalent control fermentations conducted with glucose in the absence and presence of AYG dye. Higher DyP activity levels, 4,043 and 4,902 IU/L, were obtained for fermentations conducted on glycerol, equivalent to 2.6-fold and 3.16-fold higher than the activity observed when glucose is used as the carbon source. The differential regulation of the DyP-encoding genes in P. ostreatus were explored, evaluating the carbon source, the growth phase, and the influence of the dye. The global analysis of the expression patterns throughout the fermentation showed the up- and down- regulation of the three Pleos-dyp genes evaluated. The highest induction observed for the control media was that found for the Pleos-dyp1 gene, which is equivalent to an 11.1-fold increase in relative expression (log2) during the stationary phase of the culture (360 h), and for the glucose/AYG media was Pleos-dyp-4 with 8.28-fold increase after 168 h. In addition, glycerol preferentially induced the Pleos-dyp1 and Pleos-dyp2 genes, leading to respective 11.61 and 4.28-fold increases after 144 h. After 360 and 504 h of culture, 12.86 and 4.02-fold increases were observed in the induction levels presented by Pleos-dyp1 and Pleos-dyp2, respectively, in the presence of AYG. When transcription levels were referred to those found in the control media, adding AYG led to up-regulation of the three dyp genes throughout the fermentation. Contrary to the fermentation with glycerol, where up- and down-regulation was observed. The present study is the first report describing the effect of a less-metabolizable carbon source, such as glycerol, on the differential expression of DyP-encoding genes and their corresponding activity.

Dietary incorporation of brown seaweed spent oyster mushroom substrate alters growth performance, physiological responses and meat quality parameters in Boschveld roosters.

Use of brown seaweed (Ecklonia maxima) as a nutraceutical source in indigenous chicken diets is limited by high dietary fibre levels. Inoculating seaweeds with oyster mushroom (Pleurotus ostreatus) spawn (OMS) could enhance the utility of the spent mushroom substrate (SMS). This study investigated the effect of feeding incremental levels of brown seaweed SMS on growth performance, physiological responses, and meat quality parameters in Boschveld roosters. A total of 324, 4-week-old Boschveld roosters were weighed and randomly allotted to 36 pens (9 birds per pen) to produce six replicates per dietary treatment. The diets were formulated as follows: a standard grower diet (CON); and CON containing 150 g/kg of brown seaweed inoculated with OMS at 0 (SMS0), 20 (SMS20), 30 (SMS30), 40 (SMS40) and 50% (SMS50). Birds fed diet CON had the least feed intake (p < 0.05) than all the other SMS treatment levels in weeks 7, 8, 12, 14 and 15. Diet SMS40 promoted higher (p < 0.05) body weight gain (BWG) than CON in weeks 6, 7, 9 and 14. Gain-to-feed ratio linearly increased in weeks 7 [R2 = 0.288; p = 0.010], 11 [R2 = 0.581, p = 0.0001] and 14 [R2 = 0.389, p = 0.004], respectively. Quadratic responses (p < 0.05) were observed for BWG in week 5, white blood cells, heterophils, platelets, lymphocytes, monocytes, and relative spleen and large intestine weights as OMS levels increased. Linear increases were recorded for slaughter [R2 = 0.197, p = 0.017] and breast weights [R2 = 0.197, p = 0.020] as OMS levels increased. Diet SMS0 promoted higher (p < 0.05) relative caeca weights than the CON and SMS treatment groups. Neither quadratic nor linear responses (p > 0.05) were observed for breast meat quality parameters. In conclusion, feeding brown seaweed SMS improved growth performance and slaughter weight, altered some blood parameters and internal organs, without affecting breast meat quality of Boschveld roosters. Based on the quadratic response for BWG, the optimum OMS level was deduced at 20% in a brown seaweed-based Boschveld rooster diet.

In vitro digestibility and angiotensin converting enzyme (ACE) inhibitory activity of solid-state fermented fava beans (Vicia faba L.).

Reducing the content of quickly absorbed carbohydrates and saturated fats in snack formulations while increasing the consumption of high-quality proteins are effective strategies to prevent obesity in childhood. Thus, the nutritional value, digestibility, and functionality of fava beans (Vicia faba L.) fermented with Pleurotus ostreatus were examined as potential ingredients for food design. Solid-state fermentation enhanced the protein content by 16% with a rise in essential (25%) and non-essential (15%) amino acids while decreasing total carbohydrate content and tannin levels. Moreover, fermentation modified the amino acid profile released during digestion, increasing amino acids such as valine, isoleucine, and threonine, which are vital for health and development in childhood. Furthermore, the bioaccessible fraction of the fermented bean showed a 60% of ACE inhibition and improved magnesium bioaccessibility. Consequently, fava beans fermented with Pleurotus ostreatus emerged as a new ingredient in the development of new protein-rich snacks tailored for children and adolescents.

Accumulation of Bisphenol A® by Pleurotus spp.-Flow Injection Analysis.

A specific feature of mushrooms (including those of the genus Pleurotus) is their natural ability to absorb and accumulate many chemical substances present in their immediate environment, which makes them an excellent natural sorption material. Hence, fruiting bodies of mushrooms have been recognized for years as excellent indicators of the environment, reflecting its current state. Nevertheless, mushrooms can accumulate both health-promoting substances, such as bioelements, and toxic substances, such as heavy metals and organic compounds, including bisphenol A® (BPA). This organic chemical compound in the phenol group, although it has been withdrawn in the EU since 2010, is widely present in the environment around us. In the present experiment, we aimed to determine the effect of adding BPA to liquid media for in vitro cultures of Pleurotus spp. The biomass increases were determined. Moreover, the degrees of adsorption and desorption of BPA from the obtained freeze-dried biomass in two different environments (neutral and acidic) were determined as a function of time. This is the first study to determine the bioavailability of adsorbed BPA in obtained biomass by extracting the mycelium into artificial digestive juices in a model digestive system. BPA was added to the liquid Oddoux medium in the following amounts: 0.01, 0.5, and 0.5 g/250 mL of medium. The amounts of adsorbed and desorbed BPA were determined by flow injection analysis (FIA) with amperometric detection. The addition of BPA to the substrate reduced the biomass growth in each of the discussed cases. BPA adsorption by the mycelium occurred at over 90% and depended on the morphology of the mushroom (structure, surface development, and pore size). BPA desorption depended on the pH of the environment and the desorption time. Mushrooms are an excellent natural remedial material, but BPA is extracted into artificial digestive juices; therefore, consuming mushrooms from industrialized areas may have health consequences for our bodies.

Tea and Pleurotus ostreatus intercropping modulates structure of soil and root microbial communities.

Intercropping with Pleurotus ostreatus has been demonstrated to increase the tea yield and alleviate soil acidification in tea gardens. However, the underlying mechanisms remain elusive. Here, high-throughput sequencing and Biolog Eco analysis were performed to identify changes in the community structure and abundance of soil microorganisms in the P. ostreatus intercropped tea garden at different seasons (April and September). The results showed that the soil microbial diversity of rhizosphere decreased in April, while rhizosphere and non-rhizosphere soil microbial diversity increased in September in the P. ostreatus intercropped tea garden. The diversity of tea tree root microorganisms increased in both periods. In addition, the number of fungi associated with organic matter decomposition and nutrient cycling, such as Penicillium, Trichoderma, and Trechispora, was significantly higher in the intercropped group than in the control group. Intercropping with P. ostreatus increased the levels of total nitrogen (TN), total phosphorus (TP), and available phosphorus (AP) in the soil. It also improved the content of secondary metabolites, such as tea catechins, and polysaccharides in tea buds. Microbial network analysis showed that Unclassified_o__Helotiales, and Devosia were positively correlated with soil TN and pH, while Lactobacillus, Acidothermus, and Monascus were positively correlated with flavone, AE, and catechins in tea trees. In conclusion, intercropping with P. ostreatus can improve the physical and chemical properties of soil and the composition and structure of microbial communities in tea gardens, which has significant potential for application in monoculture tea gardens with acidic soils.

Use of Ozone as a Substrate Treatment for the Control of Trichoderma in the Production of Pleurotus ostreatus.

Pleurotus ostreatus is one of the most widely cultivated species in the world. It can be produced in many lignocellulosic substrates after carrying out a treatment to eliminate competing microorganisms. The most commonly used is pasteurization by steam or by immersion in hot water. The aim of this work is to evaluate if ozone can be employed as treatment for decontamination of the substrate used for the production of the edible mushroom P. ostreatus to control of green mold Trichoderma. Wheat straw was employed as a substrate. We used two different methodologies: bubbling ozone into a tank with water and the substrate, and injecting ozone into a closed tank with the substrate inside. Ten treatments were carried out including two treatments with inoculation by a spray of conidia of Trichoderma. The effect of ozone on the conidia was also evaluated. We found that the treatment of the substrate with ozone in immersed water resulted more effective (lower growth of Trichoderma) than injecting ozone into a closed tank. Anyway, we found that the contaminant fungi could grow on the substrate in both treatments with ozone. We observed that although ozone affected the conidia when it was bubbled into water, some of them still managed to survive and could germinate 72 h later. P. ostreatus could grow and produce fruiting bodies on a substrate that was previously treated with ozone and yields were not affected. Based on the results obtained, we conclude that ozone may not be an effective agent to control Trichoderma in highly contaminated substrates, at least in the experimental conditions that we used, for the production of P. ostreatus.

Nutritional and antioxidant potential of Pleurotus djamor (Rumph. ex Fr.) Boedijn produced on agronomic wastes banana leaves and sugarcane bagasse substrates.

Global food production faces challenges concerning access to nutritious and sustainably produced food. Pleurotus djamor, however, is an edible mushroom that can be cultivated on agricultural waste. Considering that nutritional and functional potential of mushrooms can change based on cultivation conditions, we examined the influence of substrates with different compositions of banana leaf and sugarcane bagasse on the nutritional, mycochemical, and antioxidant properties of P. djamor. The mushrooms were grown for 120 days and dried in a circulating air oven at 45 °C for three days. We conducted bromatological analyses and mycochemical characterization (1H-NMR, total phenolics, and flavonoids) of the mushrooms and assayed the antioxidant activity of extracts from the dried mushrooms using an ethanol/water solution (70:30 v/v). In general, the substrates produced mushrooms with high protein (18.77 ± 0.24% to 17.80 ± 0.34%) and dietary fiber content (18.02 ± 0.05% to 19.32 ± 0.39%), and with low lipid (0.28 + 0.08% to 0.4 + 0.6%), and caloric content (maximum value: 258.42 + 8.49), with no significant differences between the groups (p ≥ 0.05). The mushrooms also exhibited high levels of total phenolics and flavonoids. The mushrooms cultivated on sugarcane bagasse substrates presented the highest values (p < 0.05). Analysis of the 1H-NMR spectra indicates an abundant presence of heteropolysaccharides, ß-glucans, α-glucans, and oligosaccharides, and all the mushroom extracts exhibited high antioxidant activity. In conclusion, our study demonstrates that agricultural residues permit sustainable production of edible mushrooms while maintaining nutritional and functional properties.

Identification of two genes essential for basidiospore formation during the postmeiotic stages in Pleurotus ostreatus.

A sporeless strain is an important breeding target in the mushroom industry. However, basidiospore production in the oyster mushroom Pleurotus ostreatus has been shown to be impaired by single-gene mutations in only two meiosis-related genes, mer3 and msh4. This study proposed a strategy for identifying the genes essential for basidiospore formation after meiotic division to determine new targets for molecular breeding. RNA-seq analysis was performed to identify P. ostreatus genes that are specifically expressed in the gill tissue of fruiting bodies, where basidiospore formation occurs. Transcriptome data during fruiting development of Coprinopsis cinerea, in which the meiotic steps progress synchronously, were then used to identify genes that are active in the postmeiotic stages. Based on these comparative analyses, five P. ostreatus genes were identified. Plasmids containing expression cassettes for hygromycin B-resistance screening, Cas9, and single-guide RNA targeting each gene were introduced into the protoplasts of dikaryotic strain, PC9×#64, to generate dikaryotic gene disruptants. Among the obtained transformants, three dikaryotic pcl1 disruptants and two cro6c disruptants did not produce basidiospores. Microscopic analyses indicated that spore formation was arrested at particular stages in these gene disruptants. These results indicate that these two genes are essential for mature spore formation in this fungus.

An enhanced productivity of pink oyster mushroom with improved nutritional profile, characterization and attempt for commercial exploitation.

BACKGROUND: An attempt has been made to explore the nutritional profile of pink oyster mushrooms that have been grown in various agricultural residues, including sugarcane bagasse, rice straw, coconut coir and sawdust, along with other nutrient supplements such as defatted mustard and chickpea powder, for appropriate growth and fruiting body formation in a short span of time. The spawn production was experimented with five different grain varieties. The study became interesting when the observations differed slightly from the traditional practices, with the addition of defatted mustard supplements resulting in a positive correlation with respect to reducing the fruiting time, as well as improving yield and the nutritional profile of Pleurotus djamor. RESULTS: An elevated yield of 651.93 g kg-1 was recorded in the medium where the RS and DM were used in the ratio of 1:0.01 (rice straw +1% w/w defatted mustard) bag, whereas, in terms of protein content, a maximum yield of 32.57 ± 0.79 mg g-1 was observed when SB:DM was in the same ratio (sugarcane bagasse +1% w/w defatted mustard) bag. CONCLUSION: To confer the best outcomes from the screened substrates, a series of experiments were performed by varying the concentration of RS and SB, with 1% w/w DM. It is worth noting that the highest protein content of 32.76 ± 0.38 mg g-1 was obtained along with the total yield of 702.56 ± 2.9 g kg-1 of mushroom when the ratio of RS:SB was 0.7:0.3. © 2024 Society of Chemical Industry.

Fungi anaesthesia.

Electrical activity of fungus Pleurotus ostreatus is characterised by slow (h) irregular waves of baseline potential drift and fast (min) action potential likes spikes of the electrical potential. An exposure of the myceliated substrate to a chloroform vapour lead to several fold decrease of the baseline potential waves and increase of their duration. The chloroform vapour also causes either complete cessation of spiking activity or substantial reduction of the spiking frequency. Removal of the chloroform vapour from the growth containers leads to a gradual restoration of the mycelium electrical activity.

The effect of light conditions on the content of selected active ingredients in anatomical parts of the oyster mushroom (Pleurotus ostreatus L.).

This study aimed to evaluate the effect of cultivation conditions in the context of light on the retention of selected vitamins, minerals and polyphenols in the stem and cap of the oyster mushroom (Pleurotus ostreatus L.). Additionally, the effect of the retention of bioactive components on the antioxidant activity of mushroom extracts was evaluated, taking into account the morphological part. Oyster mushrooms grown in the light of 200 lux had higher riboflavin content compared to mushrooms exposed to the light of lower intensity. The thiamine content of the mushrooms dropped with decreasing light intensity during cultivation. The content of biologically active compounds was found to be equal in the stem and the cap. In the case of riboflavin, it was shown that its contents in cap fractions, irrespective of the cultivation method, was statistically significantly higher than in stems. The mineral composition of caps and stems differed from each other. No differences in Zn and Cu content between the morphological parts of the mushroom studied were found. However, it was shown that the stems, regardless of the type of light, contained less iron, magnesium and sodium. Thus, it was observed that limited light exposure caused an increase in the content of total polyphenolic compounds, which did not correlate with antioxidant activity. There was no effect of the light on the antioxidant activity of mushrooms. It was also shown that stem extracts had higher antioxidant activity compared to the extracts obtained from the caps. This findings point to the possibility and potentail of use both fraction of mushrooms in the new food products development.

Effect of common foods as supplements for the mycelium growth of Ganoderma lucidum and Pleurotus ostreatus on solid substrates.

The transition from a linear to a circular economy is urgently needed to mitigate environmental impacts and loss of biodiversity. Among the many potential solutions, the development of entirely natural-based materials derived from waste is promising. One such material is mycelium-bound composites obtained from the growth of fungi onto solid lignocellulosic substrates, which find applications such as insulating foams, textiles, packaging, etc. During growth, the fungus degrades and digests the substrate to create a web-like stiff network called mycelium. The development of the mycelium is influenced by several factors, including the substrate composition. As food waste accounts for nearly 44% of total municipal solid waste, incorporating food in the substrate composition could be a means to increase the nutrients absorbed by the fungus. In this paper, we study the effects of the addition of food supplements on the growth of two fungal species, Ganoderma lucidum and Pleurotus ostreatus. The substrates, the food supplements, and the mycelia are characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and optical microscopy. Our results show that addition of barley as a supplement significantly boosts the growth of G. lucidum and P. ostreatus. Using a common food as a nutritious enrichment for the development of mycelium is a simple and straightforward strategy to create waste-based mycelium-bound biocomposites for a large range of applications, on-site, therefore promoting a circular economy.

Combined effect of olive pruning residues and spent coffee grounds on Pleurotus ostreatus production, composition, and nutritional value.

No previous study assessed the combined effect of olive pruning residues (OLPR) and spent coffee grounds (SCG) on P. ostreatus production and nutritional value. The aim of this study was to determine the capacity of P. ostreatus to degrade lignocellulosic nature of combined OLPR and SCG as well as their resultant nutrient composition. A complete randomized design was adopted with five treatments: S1:100%wheat straw (WS) (control), S2:33%WS+33%SCG+33%OLPR,S3:66%WS+17%SCG+17%OLPR,S4:17%WS+66%SCG+17%OLPR, and S5:17%WS+17%SCG+66%OLPR, and ten replicates per treatment. Substrate's and mushroom's composition were analyzed on chemical scale, including fatty acids and heavy metals profiles, following international standards. Only S1, S2, and S3 were productive, with comparable biological yield, economical yield, and biological efficiency. Organic matter loss decreased with increasing proportions of OLPR and SCG. Percentage lignin loss was higher in S1 than in S2 and S3 (53.51, 26.25, and 46.15% respectively). Mushrooms of S3 had some enhanced nutritional attributes compared to control: decrease in fat, increase in protein, increase in monounsaturated fatty acids, and lower zinc accumulation. Lead was less accumulated in S2 than S1 mushrooms. Sodium content of mushroom decreased in S2 and S3. The latter substrates yielded mushrooms with lower polyunsaturated fatty acids (PUFA) and higher saturated fatty acids (SFA) contents. All mushrooms had a valuable PUFA/SFA. This study suggests using OLPR and SCG in low proportions as nutritional supplements to the commercial wheat straw.

Alternative oxidase gene induced by nitric oxide is involved in the regulation of ROS and enhances the resistance of Pleurotus ostreatus to heat stress.

BACKGROUND: In China, during the cultivation process of Pleurotus ostreatus, the yield and quality of fruiting bodies are easily affected by high temperatures in summer. Nitric oxide (NO) plays an important regulatory role in the response to abiotic stress, and previous studies have found that NO can induce alternative oxidase (aox) experssion in response to heat stress (HS) by regulating aconitase. However, the regulatory pathway of NO is complex, and the function and regulation of the aox gene in the response to HS remain unclear. RESULTS: In this study, we found that NO affected nicotinamide adenine dinucleotide (NADH) and adenosine triphosphate (ATP) levels, reduced hydrogen peroxide (H2O2) and superoxide anion (O2-) contents, and slowed O2- production. Further RNA-Seq results showed that NO regulated the oxidation-reduction process and oxidoreductase activity, affected the cellular respiration pathway and activated aox gene expression. The function of aox was determined by constructing overexpression (OE) and RNA interference (RNAi) strains. The results showed that the OE-aox strains exhibited obviously improved growth recovery after exposure to HS. During exposure to HS, the OE-aox strains exhibited reduced levels of NADH, the product of the tricarboxylic acid (TCA) cycle, and decreased synthesis of ATP, which reduced the production and accumulation of reactive oxygen species (ROS), whereas the RNAi-aox strains exhibited the opposite result. In addition, aox mediated the expression of antioxidant enzyme genes in the mycelia of P. ostreatus under HS through the retrograde signaling pathway. CONCLUSIONS: This study shows that the expression of the aox gene in P. ostreatus mycelia can be induced by NO under HS, that it regulates the TCA cycle and cell respiration to reduce the production of ROS, and that it can mediate the retrograde signaling pathway involved in the mycelial response to HS.

Would it be possible to use nonpathogenic fungi to improve the turnover of crop residues?

This study was aimed to assess the suitability of four fungal species for operating in the residues of three crops in Golestan province, Iran. For this, four experiments were conducted to analyze their ability to grow on five culture media (Experiment I) and on the residues (Experiment II) and their growth responses to different pHs (Experiment III) and temperature levels (Experiment IV). Then, the possibility of establishing these fungi in the cultivated lands of studied crops was examined. Fungal growth was high on soybean and cotton residues and low on those of rice, and all the fungi produced a significant reduction in the carbon to nitrogen ratios in relation to noninoculated residues. The amount of nitrogen in fungal-treated cotton residues increased about four times compared with the control and in other studied residues increased twice as much as the control. The lowest C:N values for cotton and rice residues were found for Pleurotus ostreatus while Aspergillus niger was the most efficient for those of soybean. The results also showed that these fungi will not show the best performance in respect to temperature and pH, but will not be ineffective. The results could be the basis for further studies on the use of these fungi to improve nutrient cycling, focusing on multicriteria zoning on climatic and soil-related components.

Effects of exogenous ascorbic acid on the mycelia growth and primordia formation of Pleurotus ostreatus.

Primordia formation is the first and most critical step in the development of fruiting bodies of edible fungi. In this study, the effects of exogenous ascorbic acid (ASA) on the Pleurotus ostreatus mycelia growth and primordia formation were researched and the results showed that the growth rate of P. ostreatus mycelia was accelerated and the time of primordia formation was advanced. The protein content and ascorbate oxidase (AAO) activity analysis showed that with the increase of ASA concentration, the protein content of mycelia first decreased and then increased, and in a certain concentration range, exogenous ASA could significantly promote the activity of AAO. Further expression analysis of the development regulating genes (Pofst3 and Pofst4) as well as blue light receptor coding genes (PoWC-1 and PoWC-2) showed the expression levels of those four genes all changed after the exogenous ASA addition, which indicated that the expression changes of PoWC-1 and PoWC-2, two key genes in the light morphogenesis, might affect the expression levels of development regulating genes Pofst3 and Pofst4, so as to lead to the formation of primordia in advance.

Advanced mycelium materials as potential self-growing biomedical scaffolds.

Mycelia, the vegetative part of fungi, are emerging as the avant-garde generation of natural, sustainable, and biodegradable materials for a wide range of applications. They are constituted of a self-growing and interconnected fibrous network of elongated cells, and their chemical and physical properties can be adjusted depending on the conditions of growth and the substrate they are fed upon. So far, only extracts and derivatives from mycelia have been evaluated and tested for biomedical applications. In this study, the entire fibrous structures of mycelia of the edible fungi Pleurotus ostreatus and Ganoderma lucidum are presented as self-growing bio-composites that mimic the extracellular matrix of human body tissues, ideal as tissue engineering bio-scaffolds. To this purpose, the two mycelial strains are inactivated by autoclaving after growth, and their morphology, cell wall chemical composition, and hydrodynamical and mechanical features are studied. Finally, their biocompatibility and direct interaction with primary human dermal fibroblasts are investigated. The findings demonstrate the potentiality of mycelia as all-natural and low-cost bio-scaffolds, alternative to the tissue engineering systems currently in place.

Nutritional analysis and molecular characterization of hybrid mushrooms developed through intergeneric protoplast fusion between Pleurotus sajor-caju and Calocybe indica with the purpose to achieve improved strains.

Two edible mushrooms Calocybe indica and Pleurotus sajor-caju were chosen as parent strains in this study to approach the concept of hybridization through the protoplast fusion technique. Protoplast fusion in presence of polyethylene glycol (PEG) was conducted between the parent strains and by further double selection screening method, six somatic hybrid lines were developed. Those fruit bodies of the hybrid lines showed phenotypic resemblance with Pleurotus sajor-caju when grown on paddy straw under favorable conditions. The hybridity of the newly developed somatic hybrid strains was established by barrage reaction, morphological traits, fruitbody parameter and, inter single sequence repeat (ISSR) profiling. One-way analysis of variance (ANOVA) was used for the analysis of phenotypic data of hybrid lines and parents. Five ISSR primers were used to generate 51 amplified DNA fragments ranged between 250 and 3000 bp in size in six hybrids and two parents with 90.19% polymorphism. Some of the hybrids contain some non-parental bands which indicate that recombination might happen in the hybrid genome hence confirming the hybridity of newly developed strains. The dendrogram was created using the Average Linkage (Between Groups) method based on ISSR profiling and genetic distance between parent-hybrids and hybrid-hybrid was analyzed by Jaccard's proximity matrix. A definite improvement in nutritional properties and biological activity was observed in the study. Due to ease in their cultivation, it can play a significant role in the rural economic development.

Identification of hydrophobin genes and their physiological functions related to growth and development in Pleurotus ostreatus.

Hydrophobins are small secreted proteins with important physiological functions and potential applications. Here, Pleurotus ostreatus hydrophobin genes were systematically analyzed: they were characterized, classified, and their expression profiles and gene functions were explored. In total, 40 P. ostreatus hydrophobin genes were found and showed genetic diversity, of which 15 were newly identified. The hydrophobin protein sequences were diverse but all contained eight cysteine residues with a conserved spacing pattern, and 33 of them were class I hydrophobins. The expression profile analyses showed that Vmh3 and Hydph20 were abundant in monokaryotic and dikaryotic mycelia, whereas Hydph17, Po.hyd16, Hydph8 were specifically expressed in monokaryotic mycelia and Po.hyd10 were specific in dikaryotic mycelia. Furthermore, Vmh3, Hydph20, Po.hyd7, and Po.hyd10 were abundant when dikaryotic mycelia cultivated on PDA, which are different from on substrate (Vmh2, Vmh3, Hydph7, Po.hyd3, Po.hyd7, Po.hyd9); Hydph12, POH1, and Po.hyd4 can be induced by natural light and cold stimulation during development from mycelia to primordia; Vmh3, FBH1, Hydph12, Po.hyd1-Po.hyd5, and Po.hyd8 were highly expressed in primordia and young fruiting bodies; Hydph12, Po.hyd1, Po.hyd4, and Po.hyd5 were specifically expressed in pilei. In addition, RNAi transformants of FBH1 exhibited slower growth rates and had fewer primordia and fruiting bodies, which suggests FBH1 affects the growth rate and primordia formation of P. ostreatus. Therefore, P. ostreatus hydrophobin genes belong to a large family and are temporally and spatially expressed to meet the developmental needs of mushroom.

Cultivating oyster mushrooms on red grape pomace waste enhances potential nutritional value of the spent substrate for ruminants.

The use of red grape pomace (GP; Vitis vinifera L. var. Shiraz) as a source of beneficial bioactive compounds in ruminant diets is limited by high levels of indigestible compounds in the grape skin matrix. This problem demands innovative, inexpensive, and easy-to-use strategies that improve the digestibility of GP. The bioconversion of GP using edible oyster mushrooms (Pleurotus ostreatus) is one such strategy that has not been previously explored. Therefore, this study evaluated the effect of cultivating oyster mushrooms on GP on chemical composition and in vitro ruminal fermentation parameters of the spent mushroom substrate. The GP was inoculated with oyster mushroom spawns at 0, 200, 300, 400, or 500 g/kg, and incubated for 4 weeks. Organic matter, acid detergent lignin, sodium, manganese, cobalt, and copper linearly declined (P < 0.05) as spawn rates increased. A quadratic trend was observed for crude protein, neutral detergent fibre, acid detergent fibre, magnesium, phosphorus, and calcium content in response to increasing spawn rates. Higher spawning rates (20-50%) had a positive effect (P < 0.05) on gas production from the immediately fermentable fraction (a), rate of gas production from the slowly fermentable fraction (c) and effective gas production. However, gas production from the slowly fermentable fraction (b) and potential gas production linearly declined in response to increasing spawning rates. There was a linear increase (P < 0.05) in the immediately degradable fraction (a), while quadratic effects were observed for partition factors, effective degradability, and in vitro organic matter degradability at 48 h in response to spawning rates. It can be concluded that inoculating GP with oyster mushroom spawn reduced fibre content while increasing crude protein content and in vitro ruminal fermentation efficiency of red grape pomace. Based on the quadratic responses of partition factors at 48 hours post-inoculation, the optimum spawning rate for maximum ruminal fermentation efficiency of GP was determined to be 300 g/kg.