Layer Of Mycelium Research Articles

Functionality of Surface Mycelium Interfaces in Wood Bonding.

Filamentous fungi have been considered as candidates to replace petroleum-based adhesives and plastics in novel composite material production, particularly those containing lignocellulosic materials. However, the nature of the role of surface mycelium in the adhesion between lignocellulosic composite components is not well-known. The current study investigated the functionality of surface mycelium for wood bonding by incubating Trametes versicolor on yellow birch veneers and compared the lap-shear strengths after hot-pressing to evaluate if the presence of surface mycelium can improve the interface between two wood layers and consequently improve bonding. We found that the lap-shear strength of the samples was enhanced by the increase of surface mycelium coverage up to 8 days of incubation (up to 1.74 MPa) without a significant wood weight loss. We provide evidence that the bottom surface of the mycelium layer is more hydrophilic, contains more small-scale filamentous structure and contains more functional groups, resulting in better bonding with wood than the top surface. These observations confirm and highlight the functionality of the surface mycelium layer for wood bonding and provide useful information for future developments in fully biobased composites manufacturing.

First Report of Green Mold Disease Caused by Trichoderma hengshanicum on Ganoderma lingzhi

Ganoderma lingzhi is a well-known source of natural fungal medicines which has been given for the treatment of several diseases. China is one of the major commercial producers of Ganoderma mushroom worldwide. However, with the expansion of the commercial cultivation, the occurrence of the fungal diseases on G. lingzhi has also been increased. The green mold disease symptoms were observed in the cultivation base of G. lingzhi in Zuojia Town, Jilin City, Jilin Province, China, causing the basidiomes to be rotten and withered, and the green mycelium layer generated gradually. The pathogenicity tests showed the same symptoms as appeared naturally in Zuojia mushroom base. Morphology characters revealed conidia green, ellipsoid, globose, 2.56–4.83 × 2.09–4.22 μm, length-width ratio was 1.1–1.2 (n = 10). Conidiophores trichoderma-like, often asymmetry, branches solitary, paired or in whorls of 3 phialides formed solitary, paired or in whorl, variable in shape, lageniform, sometimes ampulliform or subulate. While using molecular methodology, comparing with the sequences of Trichoderma hengshanicum from GenBank, the analyzed sequence showed 97.32% homology with the RPB2 sequences, 100% with the TEF1-α sequences. A fungus isolated from the diseased tissues was identified based on morphology and molecular studies as T. hengshanicum. This is the first report of T. hengshanicum causing the green mold disease of G. lingzhi in China.

Relationship between the honeydew of mealy bugs and the growth of Phlebopus portentosus.

Phlebopus portentosus and mealy bugs form a fungus-insect gall on the roots of host plants. The fungus and mealy bugs benefit mutually through the gall, which is the key link in the nutritional mechanism of P. portentosus. The cavity of the fungus-insect gall provides an ideal shelter for mealy bugs survival and reproduction, but how does P. portentosus benefit from this symbiotic relationship? Anatomical examination of fungus-insect galls revealed that one or more mealy bugs of different generations were living inside the galls. The mealy bug's mouthpart could penetrate through the mycelium layer of the inside of the gall and suck plant juice from the host plant root. Mealy bugs excreted honeydew inside or outside the galls. The results of both honeydew agar medium and quartz tests showed that the honeydew can attract and promote the mycelial growth of P. portentosus. A test of the relationship between the honeydew and the formation of the fungus-insect gall showed that honeydew promoted gall formation. All experimental results in this study show that the honeydew secreted by mealy bugs can attract and promote the mycelial growth of P. portentosus, forming a fungus-insect gall, because mealy bugs' honeydew is rich in amino acids and sugars.

Application of solid-phase extraction to agar-supported fermentation

Agar-supported fermentation (Ag-SF), a variant of solid-state fermentation, has recently been improved by the development of a dedicated 2m(2) scale pilot facility, Platotex. We investigated the application of solid-phase extraction (SPE) to Ag-SF in order to increase yields and minimize the contamination of the extracts with agar constituents. The selection of the appropriate resin was conducted on liquid-state fermentation and Diaion HP-20 exhibited the highest recovery yield and selectivity for the metabolites of the model fungal strains Phomopsis sp. and Fusarium sp. SPE applied to Ag-SF resulted in a particular compartmentalization of the culture. The mycelium that requires oxygen to grow migrates to the top layer and formed a thick biofilm. The resin beads intercalate between the agar surface and the mycelium layer, and trap directly the compounds secreted by the mycelium through a "solid-solid extraction" (SSE) process. The resin/mycelium layer is easily recovered by scraping the surface and the target metabolites extracted by methanol. Ag-SF associated to SSE represents an ideal compromise for the production of bioactive secondary metabolites with limited economic and environmental impact.

Contribution of aerial hyphae of Aspergillus oryzae to respiration in a model solid‐state fermentation system

Oxygen transfer is for two reasons a major concern in scale-up and process control in industrial application of aerobic fungal solid-state fermentation (SSF): 1) heat production is proportional to oxygen uptake and it is well known that heat removal is one of the main problems in scaled-up fermenters, and 2) oxygen supply to the mycelium on the surface of or inside the substrate particles may be hampered by diffusion limitation. This article gives the first experimental evidence that aerial hyphae are important for fungal respiration in SSF. In cultures of A. oryzae on a wheat-flour model substrate, aerial hyphae contributed up to 75% of the oxygen uptake rate by the fungus. This is due to the fact that A. oryzae forms very abundant aerial mycelium and diffusion of oxygen in the gas-filled pores of the aerial hyphae layer is rapid. It means that diffusion limitation in the densely packed mycelium layer that is formed closer to the substrate surface and that has liquid-filled pores is much less important for A. oryzae than was previously reported for R. oligosporus and C. minitans. It also means that the overall oxygen uptake rate for A. oryzae is much higher than the oxygen uptake rate that can be predicted in the densely packed mycelium layer for R. oligosporus and C. minitans. This would imply that cooling problems become more pronounced. Therefore, it is very important to clarify the physiological role of aerial hyphae in SSF. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 539–544, 2002.

Semi-continuous fumaric acid production by Rhizopus arrhizus immobilized in polyurethane sponge

Fumaric acid was produced in repeated batch processes using Rhizopus arrhizus NRRL 1526 immobilized in polyurethane sponge particles and cultivated in a fluidized-bed reactor. Fermentation conditions were established for concentration of carrier-particles and optimal concentrations of glucose nolasses (as glucose equivalent) and ammonium sulphate. Acid production was optimized (12·3 g/litre, 35·56% and 0·256 g/litre h of fumaric acid accumulation, yield and volumetric productivity of the whole process, respectively) under the following conditions: carrier-particle concentration, 20% v/v) of the working volume; glucose molasses, 50 g/litre; ammonium sulphate, alternation of cycles with 0·0 and 0·5 g/litre. The time of fermentation was 48 h per batch for a total of eight batches. Scanning electron microscopy revealed that the fungus began to grow within the particle cells but soon after the end of the first batch growth was essentially confined to the outer part of the polyurethane particle, where a peripheral layer of mycelium began to form.

Scanning Electron Microscopy of Ca-Alginate-Immobilized Aureobasidium Pullulans Grown Under Various Culture Conditions

The morphological development of a glucoamylase-producing strain of Aureobasidium pullulans immobilized Ca-alginate was investigated during semicontinuous fermentations a fluidized-bed reactor. A dense mycelium layer was developed by the fungus on the gel bead surface which gave the beads a pellet-like configuration. Varying culture conditions, such as bead, substrate and CaCl2 concentrations and aeration rate, had a consistent effect on both enzyme production and morphological development of the in situ grown cells. Optimization of the growth conditions appeared to be necessary to prevent fungal overgrowth and to enable the immobilized inoculum to continue a sustained level of glucoamylase production over a great number of transfers.

Raw‐starch Digestion by Chalara paradoxa Immobilized in Calcium Alginate Gels

AbstractThe spores of raw starch digesting fungus Chalara paradoxa were entrapped in calcium‐alginate beads and preincubated in growth medium. The fungus devoloped a mycelium layer below and on the gel bead surface so that nutrition and oxygen in this area had direct contact with mycelia. The fungus on the bead could produce amylase and could digest raw corn starch continuously for 40 d with corn steep liquor as a nitrogen source.

Morphological development of Aspergillus niger immobilized in Ca-alginate and K-carrageenan

The morphological development of citric acid producing Aspergillus niger immobilized in Ca-alginate and K-carrageenan was studied. The fungus normally developed a dense mycelium layer below and on the gel bead surfaces so that substrate and oxygen in this area had direct contact with mycelia. By this way mycelia are not only immobilized by entrapment but also in a “pellet-like” matter. Limitation of the nitrogen source induces a more interior mycelium growth, and outgrowing of free cells was minimized. In sucrose media no effect on the particle stability was observed whereas the application of potassium acetate as substrate caused the complete dissolving of the matrices.

ENZYME ACTIVITY AND CELL DIFFERENTIATION IN NEUROSPORA

Zalokar, Marko. (Yale U., New Haven, Conn.) Enzyme activity and cell differentiation in Neurospora. Amer. Jour. Bot, 46(7): 555–559. Illus. 1959.—Morphological differences were observed in vegetative cells of Neurospora of different ages and in different parts of the mycelium. The surface layer of mycelium grown in standing cultures could be separated from the deep layer. The first contained most of the growing hyphae rich in protoplasm, while the second contained heavily vacuolated hyphae laden with fat droplets. Specific activities of several enzymes were studied in conidia, young hyphae, and the surface and deep layers of mature mycelium. Succinic dehydrogenase was low in conidia and about 10 times more active in mature mycelium. The surface layer had twice the activity of the deep layer. Aldolase increased about 3 times after the germination of conidia; it was slightly lower in the surface than in the deep layer of mycelium. Tryptophan synthetase exhibited only small differences between conidia and mycelium and was slightly lower in the surface than in the deep layer. β‐galactosidase was formed in appreciable amounts only after prolonged growth and had a much higher specific activity in the deep layer. The results were discussed in connection with cell differentiation and aging.

Het toetsen van stammen vanNectria cinnabarina (Tode) fr. op levende takken in vitro

Some types of elm hybrids resistent to the Dutch elm disease turned out to be susceptible toNectria cinnabarina(Tode) Fr. This fungus may behave as a parasite, killing branches. Virulent and non-virulent strains are known. A method is described for cultivatingNectria-strains in vitro on living desinfected branches ofAcer and ofUlmus. Three weeks after inoculation with a virulent strain the branches were killed. They were covered all over by a thick layer of mycelium. The mycelium of non-virulent strains could not kill the branches. It developed only sparsely. By this method it will be possible to select the most virulent strains out of a collection of isolates in order to use them for testing elm hybrids on their resistence toNectria cinnabarina.