Mycelium

About: Mycelium is a research topic. Over the lifetime, 8923 publications have been published within this topic receiving 170993 citations.

Spore Germination and Pre-Symbiotic Mycelial Growth

Abstract: Germination, in arbuscular mycorrhizal (AM) fungi, is not regulated by host-derived signals, since their spores are capable of germination and growth, under adequate physical, chemical and microbiological conditions, in the absence of host plants. The molecular signals which relieve spore dormancy and activate the cell cycle still remain unknown, yet environmental conditions initiating germination processes have been detected in different genera and species of AM fungi. Environmental factors playing the most important roles in spore germination, such as pH, temperature, moisture, mineral and organic nutrients, host/nonhost plants, and microorganisms are reviewed here. Recent developments have contributed to the understanding of cellular and molecular events involved in the early stages of the life cycle of AM fungi, from relief of spore dormancy to pre-symbiotic mycelial growth and developmental arrest in the absence of colonization of roots. Biochemical and genetic studies indicated that germinating spores do possess the metabolic machinery for hyphal growth, that no vital metabolic pathway is blocked, and that spore reserves are not totally depleted when germlings cease growing within 15–20 days of germination in the absence of the host. Data on withdrawal of protoplasm from peripheral hyphae and on their senescence and decrease in metabolic activity have shown that a mechanism allowing propagule survival and long-term infectivity of mycelium operates when spores of AM fungi germinate in the absence of a carbon donor. This inconsistency, an obligate symbiont which germinates in the absence of its host, is the most fundamental puzzle in the way in which these obligately biotrophic organisms have survived the past 400 million years.

Probing bacterial–fungal interactions at the single cell level

Abstract: Interactions between fungi and prokaryotes are abundant in many ecological systems. A wide variety of biomolecules regulate such interactions and many of them have found medicinal or biotechnological applications. However, studying a fungal–bacterial system at a cellular level is technically challenging. New microfluidic devices provided a platform for microscopic studies and for long-term, time-lapse experiments. Application of these novel tools revealed insights into the dynamic interactions between the basidiomycete Coprinopsis cinerea and the bacterium Bacillus subtilis. Direct contact was mediated by polar attachment of bacteria to only a subset of fungal hyphae suggesting a differential competence of fungal hyphae and thus differentiation of hyphae within a mycelium. The fungicidal activity of B. subtilis was monitored at a cellular level and showed a novel mode of action on fungal hyphae.

Pa89 structure of pamamycin-607, an aerial mycelium-inducing substance of streptomyces alboniger

Abstract: Abstract Pamamycin-607 with aerial mycelium-inducing activity has been isolated from Streptomyces alboniger , and its structure with the relative stereochemistry has been determined as a novel ionophore compound ( 1 ) on the basis of spectral analysis mainly by 2D 1 H 13 C and 1 H 1 H correlation NMR and NOE difference spectroscopy.

The relationship between micro-organisms and soil aggregation.

Abstract: SUMMARY: The physical condition of soil is improved by adding readily decomposable organic material. Microbial cells and metabolic products affect soil structure by binding loose soil particles into water-stable aggregates. Experimentally, the relative aggregating power of pure cultures of micro-organisms was as follows: fungi>actinomycetes and a few gum-forming bacteria>many gum-producing bacteria>yeasts, proactinomycetes, and many bacteria; the last three groups did not improve aggregation. Fungal hyphae entangled soil particles into stable aggregates; weaker crumbs were formed by the frailer threads of actinomycetes. A few bacterial strains produced gums capable of glueing soil into water-stable aggregates, but the majority of bacterial slimes were almost useless because they remained water-soluble after drying. The cementing properties of these gums was not improved by treatment with H or Ca ions. Bacterial gums stabilized the aggregates produced from completely dispersed soils and kaolin, but not those formed with bentonite or ferric hydroxide. The pH value of the soil played a very minor part in influencing the aggregation produced by pure cultures of micro-organisms or even by soil inoculum. Mixed cultures of fungi or of actinomycetes gave slightly better aggregation than pure cultures, but neither capsulated nor non-capsulated bacteria in mixtures gave better results than single strains. More complex mixtures containing fungi, actinomycetes and bacteria gave good aggregation when all micro-organisms wrere compatible, but poor results when antagonistic bacteria inhibited the growth of either fungi or actinomycetes. The fair aggregation obtained with soil inoculum was reproduced in the laboratory by inoculating sterilized soil with complex mixtures of micro-organisms. A study was made of the relative merits of glucose, starch, blood, yeast, fungal mycelium, straw, clover and farmyard manure for encouraging aggregation by mixtures of fungi, actinomycetes and bacteria. Aggregates bound by mycelia did not last long because the hyphae were decomposed by bacteria. The temporary improvement of soil structure after the addition of organic materials can be partly explained by the action of microbes, but the permanent crumb structure of many soils must be due mainly to other causes.