Length Of Mycelium Research Articles

Nutritional influence on fungal colony growth and biomass distribution in response to toxic metals

This work examines nutritional influence on fungal colony growth and biomass distribution in response to toxic metals. In low-substrate solid medium, 0.1 mM Cd, Cu and Zn caused a decrease in radial expansion of both Trichoderma viride and Rhizopus arrhizus. However, as the amount of available carbon source (glucose) increased, the apparent toxicity of the metals decreased. These metals also affected the overall length of the fungal mycelium and branching patterns. In low-nutrient conditions, T. viride showed a decrease in overall mycelial length and number of branches in response to Cu, resulting in an extremely sparsely branched colony. Conversely, although Cd also reduced overall mycelial length to about one-third of the control length, the number of branches decreased only slightly which resulted in a highly branched colony with many aberrant features. Cu and Cd induced similar morphological changes in R. arrhizus. A large-scale mycelial-mapping technique showed that disruption of normal growth by Cu and Cd resulted in altered biomass distribution within the colony. When grown on metal-free low-substrate medium, T. viride showed an even distribution of biomass within the colony with some allocation to the periphery. However, Cu caused most of the biomass to be allocated to the colony periphery, while in the presence of Cd, most biomass was located at the interior of the colony. These results imply that such alterations of growth and resource allocation by Cu and Cd may influence success in locating nutrients as well as survival, and that these metals have individual and specific effects on the growing fungus.

The occurrence of anastomosis formation and nuclear exchange in intact arbuscular mycorrhizal networks.

• The widespread occurrence of anastomoses and nuclear migration in intact extraradical arbuscular mycorrhizal (AM) networks is reported here. • Visualization and quantification of intact extramatrical hyphae spreading from colonized roots into the surrounding environment was obtained by using a two-dimensional experimental model system. • After 7d the length of extraradical mycelium in the AM symbiont Glomus mosseae ranged from 5169mm in Thymus vulgaris to 7096mm in Prunus cerasifera and 7471mm in Allium porrum, corresponding to 10, 16 and 40mmmm-1 root length, respectively. In mycelium spreading from colonized roots of P. cerasifera and T. vulgaris, contacts leading to hyphal fusion were 64% and 78%, with 0.46 and 0.51 anastomoses mm-1 of hypha, respectively. Histochemical localization of succinate dehydrogenase activity in hyphal bridges demonstrated protoplasmic continuity, while the detection of nuclei in the hyphal bridges confirmed the viability of anastomosed hyphae. • The ability of AM extraradical mycelium to form anastomosis and to exchange nuclei suggests that, beyond the nutritional flow, an information flow might also be active in the network.

Effect of Oil on the Population, Biomass, and Viability of Fungi in Highmoor Peats

Some microbiological parameters, such as the fungal mycelium length, the number of fungal spores, the distribution profiles of micromycetes, the viability of fungal propagules, the length distribution of micromycete hyphae, and the ratio between fungal spores and yeastlike cells, can be used to determine the degree of soil contamination with oil and the concentration that is inhibitory to micromycete complexes of highmoor peats.

Effect of oil on the size of number, biomass, and viability of fungi in highmoor peats

Some microbiological parameters, such as the fungal mycelium length, the number of fungal spores, the distribution profiles of micromycetes, the viability of fungal propagules, the length distribution of micromycete hyphae, and the proportion between fungal spores and yeastlike cells, can be used to determine the degree of soil contamination with oil and the concentration that is inhibitory to the micromycete complexes of highmoor peats.

Fósforo adicionado e fungos micorrízicos arbusculares no crescimento e nutrição mineral de limoeiro-cravo [Citrus limonia (L.) OSBECK

Visando estudar a influência de fósforo adicionado e fungos micorrízicos arbusculares (FMAs) no crescimento e nutrição mineral de limoeiro-cravo, instalou-se um experimento em casa de vegetação, com delineamento inteiramente casualizado, em esquema fatorial 6 x 3, sendo os fatores: (a) seis doses de P (0, 50, 100, 150, 200 e 250 mg kg-1 de substrato) e (b) duas espécies de FMAs (Glomus etunicatum e G. intraradices) e um controle sem FMA, com três repetições, em vasos de 1,7 dm³ de substrato. Após cinco meses do transplantio das mudas de limoeiro-cravo, avaliaram-se a altura, diâmetro do caule, matéria seca da parte aérea das plantas, nutrientes acumulados na parte aérea e percentagem de colonização radicular. No substrato, avaliaram-se o comprimento de micélio extra-radicular ativo (MEA) e total (MET) de FMAs. O porta-enxerto limoeiro-cravo apresentou alta dependência micorrízica na absorção dos nutrientes, quando inoculado com G. intraradices, o que resultou em maior altura, diâmetro de caule e matéria seca da parte aérea das plantas. Apenas essa espécie de FMA formou micorriza com o hospedeiro, com valores de colonização radicular inversamente proporcionais às doses de P adicionado. Houve aumento de MEA e MET com o aumento das doses de P, com alta correlação entre o primeiro e a absorção de nutrientes. Apesar de não colonizar o hospedeiro, a infestação com G. etunicatum resultou em valores de MEA e MET superiores aos do controle, indicando, talvez, capacidade saprofítica desse fungo para sobreviver no substrato.

Produção de micélio externo por fungos micorrízicos arbusculares e crescimento da soja em função de doses de fósforo

Em uma associação entre duas espécies de fungos micorrízicos arbusculares (FMAs) (Glomus intraradices ou Gigaspora margarita) e soja (Glycine max L. Merrill cv. IAC-8), avaliaram-se a produção de massa de material seco da parte aérea (MSPA), a massa de material seco de vagens (MSV), a colonização radicular, a concentração de N, P, K, Ca, Mg, S, Cu, Fe, Mn e Zn na parte aérea e vagens, além das estimativas do comprimento de micélio externo ativo (MEA) e micélio externo total (MET). As plantas receberam cinco doses de fósforo (0, 25, 50, 100 e 200 mg kg-1) e as avaliações foram feitas em quatro épocas (15, 30, 60 e 90 dias). A inoculação da soja com G. margarita resultou em redução transitória de crescimento aos 60 dias, enquanto aumentos na MSPA devidos à inoculação com os FMAs foram mais evidentes aos 90 dias. A colonização radicular, a produção de MEA e de MET apresentaram relação negativa com o incremento das doses de P nos tratamentos com FMAs. A menor produção de MEA e a fase de crescimento lento mais prolongada observadas no tratamento com G. margarita podem ter colaborado para a redução do crescimento das plantas aos 60 dias. O comprimento de MEA produzido por G. intraradices aumentou com o tempo e diminuiu com o aumento das doses de P. Esses efeitos foram menos evidentes para G. margarita. As concentrações de Fe e Mn nas vagens aos 90 dias foram menores nos tratamentos inoculados com FMAs nas menores doses de P, nas quais foi observada maior colonização radicular.

Effectiveness of indigenous and non-indigenous isolates of arbuscular mycorrhizal fungi in soils from degraded ecosystems and man-made habitats

Culturing in soils from degraded ecosystems significantly influenced the effectiveness of indigenous arbuscular mycorrhizal fungi (AMF) isolated from disturbed and undisturbed soils. The AMF isolates from degraded or artificially created habitats (acid rain polluted site, power station fly ash deposits, spoil banks, pyrite deposit), were not, in most cases, more effective than those from undisturbed soils, when grown in symbiosis with maize in the disturbed soils. Significant effects of soil or substrate on plant growth were found, while the influence of the AMF inoculant was much less pronounced. The development of AMF isolates was reduced in soils with more adverse chemical properties irrespective of the isolate origin. The length of extraradical mycelium of AMF and NADH-diaphorase activity of the mycelium were good indicators of negative effects of stress factors in the soil.

Fungal fractal morphology of pellet formation in Aspergillus niger

Mycelial fractal values were compared to the conventional fungal morphological parameters: average total mycelial length, average number of tips and average growth unit. The fractal values were between 1.47 to 1.3 for the various submerged culture conditions of Aspergillus niger. The average pellet diameter was 1.4 mm at the fractal value of 1.47. The mycelia with fractal values close to 1 were less branched and slim.

Effect of glucose on the development ofGlomus fistulosum colonization and extraradical mycelium on maize roots

Various doses of glucose were added weekly to pots with maize growing in a mixture of soil and Perlite inoculated with the arbuscular mycorrhizal (AM) fungusGlomus fistulosum to define the effects of an additional carbon source on plant growth, mycorrhizae and other microbial features of the cultivation substratum. Higher doses of glucose (100 and 300 mg per pot) decreased plant growth and abundance of root hairs after 6 weeks of cultivation. Lower doses of glucose (10 and 30 mg per pot) had a positive effect on some characteristics of the development of the arbuscular fungus,e.g. root colonization, abundance of arbuscules, the length of extraradical mycelium associated with root surface, length of mycelium in the substratum as well as the length of both mycelia showing dehydrogenase activity as compared with variants not supplied with glucose solution. Glucose did not affect the number of spores of AM fungus. No effect of glucose was found on substratum respiration but glucose amendment increased microbial biomass and particularly the occurrence of saprophytic fungi. In a subsequent experiment focused on nonsymbiotic phase of fungal life cycle, the mycorrhizal root segments were incubated for 6 weeks in Petri dishes on membranes covered with a soil layer and supplied weekly with four glucose concentrations from 0.3 to 10 mg. Highest total length of hyphae associated with the root surface and the length of hyphae showing dehydrogenase activity was found when the lowest dose of 0.3 mg glucose was added to the soil weekly, whereas a 10 mg dose increased the length and activity of hyphae associated with a membrane. The possible mechanisms of the effects of additional labile carbon pool on the development of mycorrhizal fungus are discussed.

Effect ofAgrobacterium radiobacter on vesicular-arbuscular-mycorrhizal infection and external mycelium of maize

Agrobacterium radiobacter influenced the development of mycorrhizal infection, length of external mycelium and metabolic activity of the mycelium in a hydroponic culture system, with maize as a host plant. Infection caused byGlomus fasciculatum, and metabolic activity of the external mycelium ofG. fasciculatum andG. etunicatum, was stimulated by bacterial inoculation. The results underline the importance of the soil saprophytic microflora for development and activity of the extraradical phase of vesicular-arbuscular mycorrhizal fungi.

Contribution of ectomycorrhiza to the potential nutrient‐absorbing surface of pine

summaryThe increase in potential nutrient‐absorbing surface area of loblolly pine (Pinus taeda L.) seedlings as a result of ectomycorrhizal development was quantified. In one experimental. In one experiment, loblolly pine seedlings were inoculated with Pisolithus tinctorius Pers. Coker (Pt) after having first been grown from seed for 8 wk under a low phosphorus (P) nutrient regime. Eight weeks following inoculation, seedlings were harvested and ail components of the nutrient absorbing system (including the fungal mycelium) were quantified. External mycelium accounted for only 5% of the potential absorbing‐system dry weight, but this mycelium comprised 75% of the potential absorbing system area and over 99% of the absorbing length. In a second experiment, the P uptake and contribution to potential absorbing surface of Pt was compared to Cenococcum geophilum Fr. (Cg). Seedlings inoculated with Pt differed from those inoculated with Cg in that they (i) absorbed almost twice the P. (ii) had a higher frequency of fine‐root branching, (iii) developed an extensive network of rhizomorphs, and (iv) had over 1.5 times the mycelial absorbing surface area and over 3 times the mycelial length of Cg. We conclude that for both Pt and Cg inoculated plants, external mycelium made by far the greatest contribution to the overall potential absorbing surface area of the pine seedling. Differences in total mycelial surface area and mycelial length may account for differences in P uptake between seedlings inoculated with Pt and those inoculated with Cg.

Food- and Density-Dependent Dispersal: Evidence from a Soil Collembolan

1. Dispersal in a fungivore species of Collembola, Onychiurus armatus, in a homo- geneous soil was theoretically approached as a deterministic compartmental process, in which the movement of animals between discrete patches could be described by a series of differential equations or by the discrete geometric probability distribution, assuming a constant probability to move from one patch to the next. 2. Experiments were designed for a release of collembolans in two types of soil in a physical arrangement of distinct patches represented by vials connected by tubings to cover a distance of 40 cm. Dispersal distances of individuals were determined, and theoretical and observed distributions compared. 3. Dispersal rates, estimated from transfer rate constants, ranged from 0 020 to 1 42 day-1, suggesting that an average 0. armatus moved less than 10 cm day -1. The probability to leave a patch varied between 0 10 and 0 50. 4. Dispersal was dependent on population density, soil type and length of fungal mycelium; it was almost twice as high at a high than at a low density (90 000 and 30000 individuals m-2) in a mor soil and four times as high in a sandy compared with a mor soil. Dispersal rate decreased as the mycelial length increased, especially in a sandy soil. 5. Collembolans in a feeding phase had a higher tendency to disperse than those that were moulting. 6. Enriching the soil patch at 40 cm distance from the release point with a favoured food item, the fungal species Mortierella isabellina, increased dispersal rate by more than four times in a mor soil, suggesting that fungal odour can attract collembolans from a large distance and enhance their rate of movement more than a three-fold increase of their population density does. (Less)

Chitin and ergosterol content of extraradical and intraradical mycelium of the vesicular-arbuscular mycorrhizal fungus Glomus intraradices

A greenhouse experiment was carried out in order to compare microscopic estimations of hyphal length with chitin or ergosterol content of the vesicular-arbuscular mycorrhizal fungus (VAMF) Glomus intraradlces Schenck & Smith. Red clover ( Trifolium pratense L.) either inoculated or not with G. intraradices was grown in 30 ml plastic cylinders referred to as inoculum compartments (IC) containing the inoculum. The bottom of the IC was removed and substituted with a 40 μm nylon net which allowed the passage of mycorrhizal mycelia but prevented roots passing through. Two ICs were placed in a larger 200ml pot filled with washed sand of particle size ranging from 100 to 1000 μm. This design provided a root-free substratum (RFS) surrounding the IC from which VAM mycelia were collected using the extraradical mycelium extraction (EME) technique. The mycelia collected were used for chitin and ergosterol analysis and the mycelial length was also determined. Root colonization, chitin and ergosterol content in roots were also determined. Correlations were found between the two biochemical parameters (ergosterol and chitin content) and hyphal lengths in the RFS. Mycelial lengths in the RFS averaged 4.3 m g −1 growth medium. The concentration of chitin and ergosterol in extraradical mycelia collected from the RFS averaged 0.29 μg m −1 and 0.24 ng m −1, respectively. Considerably higher values of both substances were obtained from colonized roots growing in the IC, averaging 5.7 mg chitin g −1 root dry wt and 11.09 μg ergosterol g −1 root dry wt, indicating that most of the mycorrhizal biomass is located within the root domain. The advantages and disadvantages of each method for quantifying extraradical VAM mycelia are discussed.

Ectomycorrhizas and rhizosphere microorganisms of seedlings of Pseudotsuga menziesii (Mirb.) Franco planted on a degraded site and inoculated with forest soils pretreated with selective biocides

summaryInoculation of planting holes with small amounts of soil from a mature forest or a plantation can improve formation of ectomycorrhizas on Pseudotsuga mensiesii (Mirb.) Franco seedlings in degraded eleareuts in southwestern Oregon. To determine the component (s) of transferred soil responsible for increased ectomycorrhiza formation, we treated soil from a clearcut, a mature forest, and a plantation with one of the following: fertilizer to test for the effect of nutrients, dimethoate and carbufuran to test for the effect on microarthropods or nematodes, fumagillin to test for the effect on protozoa, captan to test for the effect on fungi, penicillin and oxytetracycline to test for the effect on bacteria, pasteurization to test for the effect of active forms of organisms. Tyndallization to test for the effect of resting forms of organisms, or water as a control. We studied the effect of inoculation with soil subjected to these treatments on number and types of ectomycorrhizas, and length of active mycelium, and number of active bacteria in the rhizosphere. Inoculation with untreated forest or plantation soils increased the number of ectomyeorrhizas but did not change the mycorrhizal types present. Most agents had different effects in different soils, inoculation with pasteurized and Tvndallized clearcut and plantation soils increased the number of Rhizopagon‐ and Thelephora‐type ectomyeorrhizas and decreased the number of active bacteria, as did untreated forest soil. We hypothesize that the role of the soil transfer is to provide a rhizosphere environment free from a deleterious organism present in the clearcut. In this environment, beneficial organisms present in the clearcut or brought in with the seedling from the nursery can proliferate.

Changes on the development ofAcaulospora scrobiculata inTrifolium pratense (red clover) roots and bulk substrate after plant burning

In a pot experiment, burning or clipping ofTrifolium pratense plants colonized by the vesiculararbuscular mycorrhizal (VAM) fungusAcaulospora scrobiculata increased the number of spores in the substrate and the abundance of vesicles. The length of external mycelium and inoculum potential increased with clipping, but decreased with plant burning. Results suggest that the loss of photosynthesising tissue does not explain the effect of burning on VAM propagule activity. ei]R O D Dixon

Development of a quantitative monoclonal antibody‐based immunoassay forhumicola ianuginosaon rice grains and comparison with conventional assays

A sensitive, specific, quantitative enzyme‐linked immunosorbent assay (ELISA) has been developed that can be used to determine the extent of mycelial growth of a sporulating thermophilic fungus, Humicola lanuginosa on the surface of rice grains. The assay employs a monoclonal antibody EC6, developed in a previous study, which does not recognize spores of the fungus. Using antigen‐coated wells, a direct linear relationship was established between dilutions of extracts from freeze‐dried mycelium (0.5 to 3 μg/ml) and absorbance values but to eliminate day‐to‐day variations it was found to be necessary to run a dilution series, prepared from stock freeze‐dried mycelium, with every test sample. The ELISA method was compared with conventional quantitative methods. Estimates of total mycelial length in freeze‐dried material by ELISA were found to be in the same order of magnitude as those determined by ergosterol and a theoretical calculation. The ELISA method also compared favourably with direct linear measurem...

Biological activity and amount of FDA mycelium in mor humus of Scots pine stands (Pinus sylvestris L.) in relation to soil properties and degree of pollution

The biological activity and the amount of living fungal mycelium in the mor humus of pine forests around an industrialized city were studied. The activities were lower in the more polluted zone than in a cleaner one but varied between sites within the zones. The relationship of these activities to the microbial environment was determined in both the total data and in the various zones separately. Soil respiration rate was positively related to ammonium nitrogen concentration of the humus in the less polluted zone but negatively in the more polluted zone, while it related negatively to total nitrogen concentration of the humus in the entire data set. DHA was partly accounted for by the variation in acidity parameters, and best by pH(CaCl2), with a positive relation. The length of FDA active fungal mycelium showed no significant variation between the zones or sites, and was thus poorly explained by the environmental variables. The weather conditions prevailing at two seasons did not explain any variation of the activities or the length of FDA mycelium, though the biological variables were in general positively related to the moisture of the humus.

Effects of Jet Fuel Spills on the Microbial Community of Soil

Hydrocarbon residues, microbial numbers, and microbial activity were measured and correlated in loam soil contaminated by jet fuel spills resulting in 50 and 135 mg of hydrocarbon g of soil. Contaminated soil was incubated at 27 degrees C either as well-aerated surface soil or as poorly aerated subsurface soil. In the former case, the effects of bioremediation treatment on residues, microbial numbers, and microbial activity were also assessed. Hydrocarbon residues were measured by quantitative gas chromatography. Enumerations included direct counts of metabolically active bacteria, measurement of mycelial length, plate counts of aerobic heterotrophs, and most probable numbers of hydrocarbon degraders. Activity was assessed by fluorescein diacetate (FDA) hydrolysis. Jet fuel disappeared much more rapidly from surface soil than it did from subsurface soil. In surface soil, microbial numbers and mycelial length were increased by 2 to 2.5 orders of magnitude as a result of jet fuel contamination alone and by 3 to 4 orders of magnitude as a result of the combination of jet fuel contamination and bioremediation. FDA hydrolysis was stimulated by jet fuel and bioremediation, but was inhibited by jet fuel alone. The latter was traced to an inhibition of the FDA assay by jet fuel biodegradation products. In subsurface soil, oxygen limitation strongly attenuated microbial responses to jet fuel. An increase in the most probable numbers of hydrocarbon degraders was accompanied by a decline in other aerobic heterotrophs, so that total plate counts changed little. The correlations between hydrocarbon residues, microbial numbers, and microbial activity help in elucidating microbial contributions to jet fuel elimination from soil.

The haustorial interface in a resistant interaction of Erysiphe pisi with Pisum sativum

The interface between Erysiphe pisi and pea cv. JI 1049 was studied at the ultrastructural and cytochemical levels and compared with those in two susceptible cultivars. Haustorial efficiencies, as indexed by the length of mycelium associated with each haustorium, and growth rates on the resistant and one susceptible cultivar were also compared. The interaction in the resistant cultivar differed from those in the susceptible cultivars in the following ways: (i) there was no contact between the host plasmalemma and the A neckband region; (ii) papillae were contiguous with the surface of the neck and thus were probably formed before haustoria and (iii) there appeared to be less polysaccharide in the extrahaustorial membrane. The extrahaustorial membrane in the resistant cultivar lacked ATPase activity, whereas the rest of the host plasmamembrane had normal activity. Each haustorium supported a significantly greater total hyphal length in the resistant than in the susceptible cultivars. Growth rates of superficial hyphae were very similar on the susceptible and resistant cultivars but there was a delay in the onset on hyphal growth on the resistant cultivar which correlated with the previously reported delay in formation of the first haustorium. In contrast to hyphal growth rates, the rate of haustorium production was significantly less in the resistant cultivar. It is proposed that resistance in cv. JI 1049 operates at the stages prior to haustorium formation, similarly to that in some non-host and partial resistance systems. Once formed, however, the function of the haustorium seems to be unimpaired, despite the observed interfacial differences.

Hyporheic biofilms — a potential food source for interstitial animals

Glass-beads (diam. = 250 µm) were buried 10 cm deep in the sediment of a stream. After an exposure of eight weeks, bacterial densities on the beads varied between 2.7 × 105 and 2.4 × 107/cm2, and the length of the fungal mycelium between 0.2 and 5.3 mm/cm2. Bacterial densities did not show any correlation with the DOC content of the water, but were positively correlated with respiration on the beads. Fungal mycelium was negatively correlated with water temperature. Acid hydrolysis of stream-exposed beads released sugars and amino acids, whose combined carbon content exceeded that of the microbial cells by a factor of at least 4. Gut extracts of Gammarus tigrinus and Tipula caloptera released amino acids and sugars from stream-exposed beads.