Mycelial Biomass Research Articles

The physiological response of Ectomycorrhizal fungus Lepista sordida to Cd and Cu stress.

Ectomycorrhizal fungi (ECMF) can develop the resistance of host plants to heavy metal stress. However, little is known about the response of ECMF to heavy metal exposure. In this study, the growth and physiological indices of Lepista sordida under Cd and Cu stress were studied. The growth of L. sordida on PDA medium under Cd and Cu stress was observed using scanning electron microscopy (SEM). After the addition of Cd and Cu to the medium, the mycelium started twisting, breaking, sticking together, and even dissolving. In the control group, a good and luxuriant mycelium growth of L. sordida along with the numerous clamp connections was observed. The mycelial biomass decreased with increasing concentrations of heavy metals in a liquid medium. The catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX) activities were also investigated, and the results showed that the Cd and Cu treatments caused a significant increase in the antioxidant enzyme activities. The contents of soluble protein, soluble sugar, and free proline in L. sordida were investigated, and it was found that the contents initially increased and then decreased with the increasing concentrations of Cd and Cu. However, the content of malondialdehyde (MDA) increased with the increasing concentrations of Cd and Cu. In conclusion, the present study provides a theoretical basis for the better utilization of Ectomycorrhizal fungal resources for the remediation of soil contaminated with heavy metal.

Valorization of oxytetracycline fermentation residue through torrefaction into a versatile and recyclable adsorbent for water pollution control

Antibiotics fermentation residue (AFR) is an environmental threat, as well as a valuable mycelial biomass resource. However, there is still a lack of safe and high-value conversion routes for AFR. Herein, torrefaction was applied to safely dispose of oxytetracycline fermentation residue (OFR) and simultaneously convert it into a high-performance adsorbent, and the adsorption performances of the resultant torrefaction char (TC) and pyrochar from pyrolysis were compared to show the advantage of torrefaction in converting the biomass waste into a functional adsorbent. Results showed that no oxytetracycline in OFR was detected after drying, and antibiotic resistant genes in OFR were reduced by > 6 logs after torrefaction, suggesting that torrefaction was efficient in eliminating environmental threats from OFR. Attributed to the richer oxygen- and nitrogen-containing functional groups, the TC far outperformed the pyrochar in adsorption performances at various conditions, suggesting that torrefaction was more efficient than pyrolysis for converting the biomass waste into a functional adsorbent. Specifically, the maximum adsorption amounts for uranium (U(VI)) and methylene blue (MB) by the TC reached 141 and 582 mg/g, respectively. Spectroscopic analyses evidenced that the oxygen-/nitrogen-containing groups on the TC dominated the adsorption of these pollutants. Moreover, no decreases of U(VI) and MB adsorption amounts and intensity of surface organic functional groups were observed for the TC after several cycles, suggesting the high reusability of the TC. Therefore, this study suggested that the AFR could be safely valorized via torrefaction into a powerful adsorbent for the removal of various pollutants from the solution.

Production of Antioxidant Bioactive Compounds during Mycelium Growth of Schizophyllum commune on Different Cereal Media

Schizophyllum commune or split gill mushroom is a nutrient-rich natural food ingredient. Even during mycelium growth, S. commune could produce the bioactive compounds including phenolic and flavonoid compounds. The aim of this research was to characterize the production of bioactive compounds during mycelium growth period of S. commune cultured onto different eight edible cereal media (sorghum, corn, barley, wheat, oat, jasmine rice, Mun Poo rice and riceberry rice). The antioxidant activities and mycelial biomass were also observed during their growth. The results show that the highest mycelial growth rate was obtained onto barley and jasmine rice, while the lowest one was found in sorghum and corn. The concentration of phenolic compounds increased along with the mycelial growth. The fungal culture on wheat significantly exhibited the highest production of phenolic compounds which was 8.56 ± 1.09 mg GAE/g DW on day 8.The highest flavonoid production of 577.35 ± 29.93 μg CE/g DW, wasremarkably found onto barley from day 6. The degradation of certain flavonoidsin cereal materials by S. commune was also observed, particularly in riceberryrice. Antioxidant activity of cultured cereals was depended on the initial activitiesof materials and was mainly increased by S. commune metabolism. The DPPH•and ABTS•+ scavenging activities were sharply increased at day 4 which was earlystage of log phase of S. commune. At day 8, most of cereal media exhibited highDPPH• activity with a half maximal inhibitory concentration (IC50) range of 3.83-5.80 mg DW/mL, except jasmine rice. Only wheat and oat could significantly givethe highest ABTS•+ scavenging activity which was in an IC50 range of 2.38-3.27mg DW/mL. The highest FRAP activity with a median effective concentration (EC50)of 2.14 ± 0.23 mg DW/mL, was observed in barley which corresponded with itshighest flavonoid content. Antioxidant activities of S. commune culture onto cerealmedia were correspondent with their phenolic and flavonoid contents. Therefore,this study assured that several antioxidative substances were interestinglyproduced by using S. commune cultured onto the selected edible cereals, whichcould be possibly developed as a new supplement or active ingredient forpharmaceutical and food industries.

Effects of nitrogen from different sources on mycelial biomass and polysaccharide production and pellet morphology in submerged cultures of Grifola frondosa

The effects of nitrogen in the medium on the production of mycelial biomass, extracellular polysaccharides (EPS), and intracellular polysaccharides (IPS) was investigated in submerged cultures of Grifola frondosa. In addition, the effects on pellet morphology were examined. The maximum production levels of mycelial biomass (2.32 g/L), EPS (1.58 g/L), and IPS (29.1 mg/L) were obtained when the nitrogen sources in the medium were yeast extract, malt extract, and peptone, respectively. Using yeast extract as the nitrogen source yielded the maximum mycelial biomass, and morphological characterization revealed a composition of 47% large pellets (fraction L), 20% small pellets (fraction S), and 33% adhesive mycelia (fraction A). The maximum circularity value and the minimum roughness value of the pellets were observed using yeast extract cultures. Both the compactness (0.53) and circularity (0.15) of the pellets were the lowest among the seven types of nitrogen sources, but the roughness (2.86) was the highest in malt extract, which was the nitrogen source that resulted in maximum polysaccharide production. The results revealed that the production levels of mycelial biomass, EPS, and IPS of G. frondosa were associated with changes in pellet morphology due to the source of nitrogen in the medium.

Isolation and identification of fungi found in contaminated fermented milk and antifungal activity of vanillin

Fungi contamination is an important factor affecting the quality and commercial value of fermented milk. Vanillin is known as a safe and efficient natural antimicrobial additive with great potential value as a food bio-preservative. In this study, the microbiological quality of fermented milk of different brands retailed in China and the antimicrobial activity of vanillin were investigated. A total of 27 fermented milk samples were purchased and evaluated. Fungal isolates obtained were characterized by DNA sequencing of the internal transcribed spacer (ITS) region. The effects of vanillin on the growth of fungi were studied by plate dilution method, radical colony diameter, and mycelium biomass. The result showed that 14.8% of the samples were contaminated with three different species of fungi with Cladosporium spp. being the most predominant fungal contaminant. The study further showed that vanillin had significant inhibitory activity against the growth of the fungi species. The cell number, radical colony diameter, and the mycelium biomass of the fungal contaminant were significantly reduced by the inhibitory action of the vanillin. The study thus provides reliable data evidence that will help relevant stakeholders in the fermented milk industries to improve their quality control strategies and consider vanillin as a bio-preservative with the potential to increase the shelf-life and safety of fermented milk.

Effect of Light-Emitting Diodes on the Mycelial Biomass Production and Antioxidant Activity of Ganoderma lucidum (W. Curt.: Fr.) P. Karst.

Light is an important factor for the growth of many forms of life, including mushrooms. This paper highlights the effects of the different wavelengths (red, 650 nm; blue, 450 nm; green, 525 nm) of light emitting diodes (LEDs) on the growth, biomass production and antioxidant properties of Ganoderma lucidum. G. lucidum is a white-rot, wood-degrading fungus in the Basiodiomycota that typically grows on logs. Mycelia were grown on coconut water agar (CWA) solid media for analysis of mycelial colony diameter as well as coconut water (CW) submerged culture for analysis of mycelial biomass weight. Both set-ups were incubated in variously-colored LED chambers. The DPPH radical scavenging activity and total phenolic content of the harvested mycelia were also determined. After three days of incubation, G. lucidum mycelia under red LED recorded the highest mean mycelial colony diameter of 72.50 mm. In terms of mycelia biomass production, G. lucidum mycelia exposed in red LED and dark produced the heaviest weight. On the other hand, mycelia grown under green LED had the highest radical scavenging activity of 66.49% while those harvested from red LED showed the highest total phenolic content of 81.29 mg GAE / g of sample. Our results demonstrate that LED color influences the mycelial growth, biomass production and antioxidant activities of G. lucidum.

Effect of Light-Emitting Diodes on the Mycelial Biomass Production and Antioxidant Activity of Ganoderma lucidum (W. Curt.: Fr.) P. Karst.

Light is an important factor for the growth of many forms of life, including mushrooms. This paper highlights the effects of the different wavelengths (red, 650 nm; blue, 450 nm; green, 525 nm) of light emitting diodes (LEDs) on the growth, biomass production and antioxidant properties of Ganoderma lucidum. G. lucidum is a white-rot, wood-degrading fungus in the Basiodiomycota that typically grows on logs. Mycelia were grown on coconut water agar (CWA) solid media for analysis of mycelial colony diameter as well as coconut water (CW) submerged culture for analysis of mycelial biomass weight. Both set-ups were incubated in variously-colored LED chambers. The DPPH radical scavenging activity and total phenolic content of the harvested mycelia were also determined. After three days of incubation, G. lucidum mycelia under red LED recorded the highest mean mycelial colony diameter of 72.50 mm. In terms of mycelia biomass production, G. lucidum mycelia exposed in red LED and dark produced the heaviest weight. On the other hand, mycelia grown under green LED had the highest radical scavenging activity of 66.49% while those harvested from red LED showed the highest total phenolic content of 81.29 mg GAE / g of sample. Our results demonstrate that LED color influences the mycelial growth, biomass production and antioxidant activities of G. lucidum.

Detection of Secondary Metabolite of Mycena pelianthina Growth in Various Liquid Medium

Mushrooms which is mostly belong to the phylum Basidiomycota have been recognized as functional foods and a source for the nutraceuticals. Genus Mycena is one of mushrooms, which has been investigated for its secondary metabolites. Mycena pelianthina produces pelianthinarubins A, pelianthinarubins B, muscarin, and epimuscarin from alkaloid group. The purposes of this research were to determine the effects of composition of medium and incubation time on production of mycelial biomass of M. pelianthina in liquid medium and to know the group of secondary metabolite compounds produced. This research was done experimentally using a Factorial Completely Randomized Design consisted of 12 treatments and three replications. The first factor was medium type, which were Mushroom Complete Medium (MCM), Potato Dextrose Yeast Broth (PDYB), and Yeast Malt Extract Medium (YM). The second factor was the incubation time consisting of 15, 20, 25, and 30 days. The observed main parameters were the dry weight of mycelial biomass and the secondary metabolite groups. The dried weights of mycelia were analyzed using analysis of variance (ANOVA), continued with Duncan test at a 95% confidence level. The best growth of M. pelianthina mycelium was produced on PDYB medium at incubation time of 20 days with an average mycelial dry weight of 0.92 g/100 mL. M. pelianthina contained secondary metabolite compound groups of alkaloids, terpenoids, and flavonoids.

A new approach to recycling cephalosporin fermentation residue into plant biostimulants

Cephalosporin fermentation residue (CFR), a byproduct of the pharmaceutical industry, mainly contains the mycelial biomass and unutilized culture medium, which can be reused as a high-quality protein source. This study first reports the recycling CFR into plant biostimulants using partial acid hydrolysis. Temperature, reaction time and ratio of hydrochloric acid/dry matter (H/S) were optimized for yielding both free amino acid and low molecular weight fraction based on response surface methodology. The crude protein concentration of CFR is 55%, with glutamic acid being the dominant amino acid (12.5%). Two favorable hydrolysis conditions were obtained: (1) 140 °C, 10.7 h, 17 H/S for maximizing the amino acid yield of 45.5 g/100 g CFR dw and (2) 100 °C, 10.7 h, 19 H/S for maximizing the low molecular weight fraction of 28.2%. The CFR-derived biostimulants obtained from two optimum conditions possessed two biostimulant modes of action: plant growth promotors/inhibitors and stress alleviators. However, they showed the differences in aminograms and profiles of low molecular weight compounds. Neither residual cephalosporin C nor its byproduct was detected in the CFR-derived biostimulants, suggesting that partial acid hydrolysis appears capable of recycling CFR into plant biostimulant safely.

Effects of Tween series and agar additives on mycelia biomass and β-glucan production by Hericium erinaceus in submerged culture

Hericium erinaceus has been widely used in food and medicine because of its various promising bioactivities. This study investigated the effects of Tween series surfactant and agar addition on mycelial growth and β-glucan in liquid submerged culture of the medicinal mushroom H. erinaceus. The addition of Tween 80 in liquid medium resulted in higher dry cell weight (DCW) and β-glucan production, with values of 6.06 and 1.21 g/L for 3.0% (w/v) and 7.27 and 1.22 g/L for 4.0% (w/v), respectively. This corresponded to a 1.82 relative ratio of DCW to control and a 1.86 relative ratio of β-glucan to control for 3.0% (w/v) and a 2.18 relative ratio of DCW to control and a 1.87 relative ratio of β-glucan to control for 4.0% (w/v), respectively. Further, the mycelial pellets were altered by the addition of agar in liquid medium, forming small pellets. The pellet diameter decreased with increasing medium viscosity, and the smallest pellet diameter, 1.5 mm, was attained with the addition of 0.3% (w/v) agar. The medium viscosity was 48.7 mPa s. Moreover, β-glucan production increased with a decreasing pellet diameter, and the highest β-glucan production, 0.86 g/L, was observed with 0.3% (w/v) agar added to the medium. The influence of flask type on DCW and β-glucan production was investigated which were almost 1.2-fold higher in baffled Erlenmeyer flasks than in normal Erlenmeyer flasks. Finally, cultivation with agar addition in a baffled Erlenmeyer flask was determined to be most effective for DCW and β-glucan production, yielding the highest values of 7.74 and 1.43 g/L, respectively.

Iron Bioaccumulation in Lentinus crinitus Mycelia Cultivated in Agroindustrial Byproducts

Iron deficiency anemia is a challenge to global public health, and the development of iron-enriched foods are an opportunity to reduce this problem. Lentinus crinitus is a basidiomycete with high metal bioaccumulation capacity that is consumed by Amazonian Indians. This study aimed to evaluate iron bioaccumulation in the mycelial biomass of L. crinitus cultivated in agroindustrial byproducts. First, the fungus grew in a liquid medium with iron addition from 0.116 (control) to 100 mg L−1. The addition of 90 mg L−1 iron to the culture medium resulted in 15.07 ± 1.44 dg kg−1 of iron mycelial bioaccumulation, a 9000-fold increase compared with the control. Then, the fungus grew in agroindustrial byproducts sugarcane (SCM) or soybean (SBM) molasses added with 90 mg L−1 iron and 0.9 mg L−1 manganese, a new element in the assay. The iron concentrations in the mycelial biomass cultivated in SCM or SBM were 20.78 ± 2.28 or 34.71 ± 4.31 dg kg−1, respectively, at 21 cultivation days. The cultivation time and the presence of iron and manganese in the culture media were important variables for iron bioaccumulation in the mycelial biomass. Our study evidenced that agroindustrial byproducts, mainly SCM, can be used to successfully produce mycelial biomass enriched with iron - as an alternative functional food - to add value to the food production chain. Also, the iron-enriched biomass can be an alternative for non-living animal protein supply.

Effect of the heme oxygenase gene on mycelial growth and polysaccharide synthesis in Ganoderma lucidum

The heme oxygenase gene has antioxidant and cytoprotective effects in organisms, but no related research has been conducted in Ganoderma lucidum. For the first time, we cloned the HMX1 gene in G. lucidum. The CDS is 1092 bp in length and encodes 363 amino acids. The HMX1 protein was prokaryotically expressed and purified, and the enzyme activity of the purified protein was measured. The value of Km was 0.699 μM, and Vm was 81.9 nmol BV h-1 nmol-1 protein. By constructing the silencing vector pAN7-dual-HMX1i, the transformants HMX1i1 and HMX1i2 were obtained. Compared with the wild-type (WT), the average growth rate of HMX1i1 and HMX1i2 decreased by 31% and 23%, respectively, and the mycelium biomass decreased by 53% and 48%, respectively. Compared with the WT, the extracellular polysaccharide content of HMX1i1 and HMX1i2 increased by 59% and 51%, and the intracellular polysaccharide content increased by 24% and 22%, respectively. These results indicate that the HMX1 gene affects mycelial growth and polysaccharide synthesis in G. lucidum.

Crecimiento in vitro de Sclerotium rolfsii en respuesta a la calidad de luz de tres tipos de lámparas fluorescentes

La investigación se realizó para conocer la influencia de la calidad de luz sobre el crecimiento radial del micelio, producción de esclerocios y biomasa de micelio de Sclerotium rolfsii cultivado in vitro. Los tratamientos consistieron en luz blanca fría, neutra y cálida, emitidas por lámparas fluorescentes, con una densidad de flujo de fotones fotosintéticos (400 a 700 nm) de ≈300 μmol m-2 s-1, los cuales se establecieron bajo un diseño completamente al azar con 10 repeticiones. El espectro luminoso emitido por las lámparas fluorescentes influyó en el crecimiento del hongo in vitro. La luz blanca fría ocasionó reducción en el crecimiento radial, biomasa y producción de esclerocios de Sclerotium rolfsii debido al mayor contenido espectral de luz azul (400-500 nm).

White mulch and irrigation increase black truffle soil mycelium when competing with summer truffle in young truffle orchards

The black truffle (Tuber melanosporum Vittad.) and the summer truffle (Tuber aestivum Vittad.) are two of the most appreciated edible fungi worldwide. The natural distributions of both species partially overlap. However, the interspecific interactions between these truffles and how irrigation and mulching techniques impact the dynamics between them are still unknown. Here, an experimental truffle plantation with Quercus ilex was established in Maials (Catalonia, Spain), combining three soil mulch treatments (white mulch, black mulch and bare soil as a control) and two irrigation regimes (irrigated and non-irrigated as a control) to investigate truffle mycelial dynamics in soil when both truffle species co-occur. The development of truffle mycelium in two different seasons (spring and autumn) in two consecutive years (2017 and 2018) was quantified using qPCR. Truffle mycelia of both species showed greatest development under white mulch. When mycelia of both truffle species co-occurred in soil, irrigation combined with white mulch resulted in greater quantities of T. melanosporum mycelial biomass, whereas the control irrigation treatment favoured the development of T. aestivum. Mulch treatments were also advantageous for seedling growth, which was expressed as root collar diameter and its increment during the study period. Significant relationships between root collar diameter and root growth and the amount of mycelial biomass in the soil were observed for both truffle species. Our results indicate the potential advantages of using white mulch to support irrigation in truffle plantations located in areas with dry Mediterranean climatic conditions to promote the development of Tuber mycelium.

Mycelial biomass production of medicinal mushroom Ganoderma P. Karst.

The fruiting body, mycelia and spores of Ganoderma contain approximately 400 different bioactive compounds. At present, the demand for natural products with pharmacological activity and medicinal uses is markedly increasing and the submerged culture offer faster production of mycelia biomass with high nutrients and exopolysaccharide of medicinal importance in shorter period of time within reduced space and gets lesser chances of contamination with consistent quality. Mycelial biomass production of Ganoderma was carried out using five different liquid media viz., Glucose aspargine media (GLM), Hwang liquid media (HLM), Potato dextrose broth (PDB), Yeast wine media (YWM) and Glucose peptone liquid media (GPM). The highest dry weight was observed in yeast wine media (1.08g/300ml).

Produção de biomassa micelial e enzimas lignocelulolíticas de Pleurotus spp. em meio de cultivo líquido

Pleurotus spp. são fungos capazes de degradar a lignocelulose graças à excreção de enzimas com diferentes aplicações industriais. O objetivo deste estudo foi avaliar a influência dos meios de cultivo na produção de biomassa micelial e na atividade de lacase, celulases e xilanase de Pleurotus spp. Pleurotus citrinopileatus U16-23, P. djamor U16-20, U16-25 e U16-28, P. eryngii U16-30, P. ostreatus U16-22 e P. pulmonarius U16-21 foram cultivados por 12 dias a 28 ºC em meio extrato de malte (EM-20 g L-1), meio definido (MD glicose 10 g L-1 e extrato de levedura 2 g L-1), ou em meio bagaço de cana-de-açúcar (BC) igual ao MD, mas substituindo glicose por bagaço (50 g L-1). O maior crescimento ocorreu no meio EM e P. djamor U16-25 a cepa que gerou mais biomassa (7,5 ± 0,1 g L-1). A maioria das cepas apresentou maior atividade de lacase no meio MD e as atividades maiores foram de P. djamor U16-25 (22243 ± 745 U L-1) e P. pulmonarius (20924 ± 46 U L-1). P. citrinopileatus e P. djamor U16-25 não produziram celulases, mas P. djamor U16-20 e P. eryngii produziram as maiores atividades de celulase nos meios EM e MD. Todas as cepas produziram xilanase em e as maiores atividades foram observadas no meio EM e P. djamor U16-28 (67154 ± 1597 U L-1) foi o maior produtor. Pleurotus djamor U16-25 se destacou como produtor de lacase e de xilanase livre de celulase revelando potencial para aplicação na indústria de papel e celulose.

Extraction and characterization of polysaccharide-enriched fractions from Phoma dimorpha mycelial biomass.

Ultrasound-assisted extraction (UAE) and pressurized hot water extraction (PHWE) were tested as advanced clean methods to obtain polysaccharides from Phoma dimorpha mycelial biomass. These methods were compared to conventional extraction (hot water extraction, HWE) in terms of polysaccharides-enriched fractions (PEF) yield. A central composite rotational design was performed for each extraction method to investigate the influence of independent variables on the yield and to help the selection of the condition with the highest yield using water as an extraction solvent. The best extraction condition of PEF yielded 12.02 wt% and was achieved when using UAE with direct sonication for 30min under the intensity of 75.11W/cm2 and pulse factor of 0.57. In the kinetic profiles, the highest yield (15.28 wt%) was obtained at 50°C under an ultrasound intensity of 75.11W/cm2 and a pulse factor of 0.93. Structural analysis of extracted polysaccharide was performed using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermal property. The water solubility index, water holding capacity, and emulsification index of PEF were 31.3 ± 1.5%, 138.1 ± 3.2%, and 62.9 ± 2.3%, respectively. The submerged fermentation demonstrates the huge potential of Phoma dimorpha to produce polysaccharides with bioemulsifying properties as a biotechnologically cleaner alternative if compared to commercial petroleum-derived compounds. Furthermore, UAE and PHWE are green technologies, which can be operated at an industrial scale for PEF extraction.

Effect of Cytokinin-Containing Extracts from Some Medicinal Mushroom Mycelia on HepG2 Cells In Vitro.

Endogenous cytokinins in mycelia of medicinal mushrooms Hericium coralloides and Fomitopsis officinalis grown in vitro were identified using high-performance liquid chromatography coupled with mass spectrometry. High amounts of zeatin-type cytokinins and isopentenyladenine were found. The qualitative composition and quantitative content of cytokinins were species-specific traits of mushrooms. Optical microscopy was used to perform a comparison analysis of the influence of crude extracts and purified cytokinin fractions from both species' mycelial biomass on HepG2 tumor cell growth in vitro and morphology. The results showed that purified cytokinin fractions from H. coralloides and F. officinalis mycelia demonstrated a cytotoxic effect on HepG2 cells, unlike crude extracts. Under the influence of all mushroom extracts, similar patterns of changes in HepG2 cell morphology were observed, but they were more pronounced for H. coralloides compared with F. officinalis. Purified fractions of both mushroom species caused an increased level of apoptosis compared to crude extracts. Some increase in glucose uptake by cultured cells was found in all investigated samples wherein the influence of H. coralloides extracts was approximately twice the effect of the corresponding F. officinalis extracts. The data obtained confirm the assumption that cytokinins are involved in the expression of therapeutic effects of medicinal mushrooms and indicate the need to take into consideration the methods of cytokinin extraction when preparing pharmacologically active drugs based on fungal raw materials. Thus, extracts from H. coralloides and F. officinalis mycelial biomass are promising in the search for anticancer agents.

Production and Nutritional Composition of King Oyster Culinary-Medicinal Mushroom Pleurotus eryngii (Agaricomycetes) Biomass from Brazil

The present study aimed to evaluate the nutritional composition and production of mycelial biomass of Pleurotus eryngii in different culture media, formulated with infusion of purple-skinned sweet potato, glucose concentrations, and the presence or absence of yeast extract. The mushroom was grown for 15 days at 25°C and 150 rpm. The best production of mycelial biomass occurred in the culture medium with 40 g/L of glucose plus yeast extract. At the second cultivation, the fungus entered the exponential growth phase from days 6 until 14. These results indicate that the insertion of nutritional sources in purple-skinned sweet potato media positively influences mycelial biomass production and its nutritional characteristics make it useful for food industry applications.

Salt stress alters pathogenic behaviour of Fusarium oxysporum f. sp. ciceris and contributes to severity in chickpea wilt incidence

Soil salinity is one of the most prominent abiotic stresses whereas wilt disease caused by Fusarium oxysporum f. sp. ciceris is the major biotic stress in chickpea. We carried out an experiment to understand the mechanism of wilt development in chickpea (cv. JG-62) by F. oxysporum f. sp. ciceris isolate 49 (Foc-49) in soil under salinity (NaCl) stress. High NaCl concentration had a negative influence on chickpea seed germination and growth while positively influenced mycelial growth and sporulation in Foc-49. Increased mycelial growth, mycelial biomass, sporulation, and microconidial production was observed in Foc-49 cultured in high NaCl concentrations. Similarly, at higher NaCl concentrations either extensive root colonization by Foc-49 or severe rotting of the roots was observed in plants challenged with or without Foc-49, respectively. In contrast, Foc-49 alone without NaCl caused extensive browning of the chickpea roots initially and rotting at a later stage. Mortality of chickpea plants was also high in the combined treatment of Foc-49 and NaCl. Additionally, results from the virulence study showed that G-protein and MAP kinase-mediated signalling were active in Foc-49 while interacting with the JG-62 plants under NaCl stress. Moreover, up-regulation of the SNF1, cell wall-degrading enzymes, and fusaric acid biosynthesis genes and down-regulation of the SIX effector genes in Foc-49 during interaction with the chickpea plants under NaCl stress indicate that soil salinity promotes growth in Fusarium sp. and push the pathogen to shift its pathogenic lifestyle towards the necrotrophic state by-passing the hemibiotrophic state.