1‐Phenyl‐3‐pentanone,a Volatile Compound from the Edible Mushroom Mycoleptodonoides aitchisonii Active Against Some Phytopathogenic Fungi

Volatiles produced by mycelia of mushrooms with aromatic odour were investigated for their antifungal activity against plant‐pathogenic fungi. The results of the screening of 23 species of basidiomycetes revealed that volatile substances from mycelia of Mycoleptodonoides aitchisonii (TUFC10099), an edible mushroom, strongly inhibited the mycelial growth, spore germination and lesion formation on host leaves of some plant‐pathogenic fungi including Alternaria alternata, A. brassicicola, A. brassicae, Colletotrichum orbiculare and Corynespora cassiicola. The volatile compounds were isolated from the culture filtrate of M. aitchisonii, and 1‐phenyl‐3‐pentanone was identified as a major antifungal volatile. The compound had significantly inhibitory activity against plant‐pathogenic fungi at 35 ppm. This is the first report that the volatile compound produced by mycelia of M. aitchisonii has antifungal activity against plant‐pathogenic fungi.     

Grazing by Folsomia candida (Collembola) differentially affects mycelial morphology of the cord-forming basidiomycetes Hypholoma fasciculare, Phanerochaete velutina and Resinicium bicolor

Cord-forming basidiomycetes are important decomposers of dead wood in forest ecosystems but the impact of mycophagous soil invertebrates on their mycelia are little known. Here we investigate the effects of different grazing intensities of Collembola (Folsomia candida) on mycelial foraging patterns of the saprotrophic cord-forming basidiomycetes Hypholoma fasciculare, Phanerochaete velutina and Resinicium bicolor growing from beech (Fagus sylvatica) wood block inocula in dishes of non-sterile soil. Mycelial extension rate and hyphal coverage decreased with increased grazing intensity. R. bicolor was most affected, high grazing density resulting in only a few major cords remaining. Grazing of H. fasciculare often resulted in points of more rapid outgrowth as cords with a fanned margin. In grazed mycelia of P. velutina the main cords had fanned tips and lateral cords became branched. These results suggest that mycophagy by Collembola may hinder the growth of cord-forming fungi in woodlands, which might impact on the ability of these fungi to forage for and decompose dead organic material.     

Ectomycorrhizal fungi: exploring the mycelial frontier

Ectomycorrhizal (ECM) fungi form mutualistic symbioses with many tree species and are regarded as key organisms in nutrient and carbon cycles in forest ecosystems. Our appreciation of their roles in these processes is hampered by a lack of understanding of their soil-borne mycelial systems. These mycelia represent the vegetative thalli of ECM fungi that link carbon-yielding tree roots with soil nutrients, yet we remain largely ignorant of their distribution, dynamics and activities in forest soils. In this review we consider information derived from investigations of fruiting bodies, ECM root tips and laboratory-based microcosm studies, and conclude that these provide only limited insights into soil-borne ECM mycelial communities. Recent advances in understanding soil-borne mycelia of ECM fungi have arisen from the combined use of molecular technologies and novel field experimentation. These approaches have the potential to provide unprecedented insights into the functioning of ECM mycelia at the ecosystem level, particularly in the context of land-use changes and global climate change.     

Fungal Decomposition of Oat Straw during Liquid and Solid-State Fermentation

White rot fungi (Coriolus hirsutus, Coriolus zonatus, and Cerrena maxima from the collection of the Komarov Botanical Institute of the Russian Academy of Sciences) and filamentous fungi (Mycelia sterilia INBI 2-26 and Trichoderma reesei6/16) were grown on oat straw–based liquid and solid media, as well as in a bench-scale reactor, either individually or as cocultures. All fungi grew well on solid agar medium supplemented with powdered oat straw as the sole carbon source. Under these conditions, the mold Trichoderma reesei fully suppressed the growth of all basidiomycetes studied; conversely,Mycelia sterilia neither affected the development of any of the cultures, nor did it show any substantial susceptibility to suppression by their presence. Pure solid cultures of basidiomycetes, as well as the coculture of Coriolus hirsutus andCerrena maxima,caused a notable bleaching of the oat straw during its consumption. When grown on the surface of oat straw–based liquid medium, the basidiomycetes consumed up to 40% of the polysaccharides without measurable lignin degradation (a concomitant process). Under these conditions, Mycelia sterilia decomposed no more than 25% of the lignin in 60 days, but this was observed only after polysaccharide exhaustion and biomass accumulation. In contrast, during solid-state straw fermentation, white rot fungi consumed up to 75% of cellulose and 55% of lignin in 83 days (C. zonarus), whereas the corresponding consumption levels for cocultures ofMycelia sterilia and Trichoderma reesei equaled 70 and 45%, respectively (total loss of dry weight ranged from 55 to 60%). Carbon dioxide–monitored solid-state fermentation of oat straw by the coculture of filamentous fungi was successfully performed in an aerated bench-scale reactor.     

Erythromycin production by Streptomyces erythreus entrapped in calcium alginate beads

Summary Mycelia of Streptomyces erythreus were immobilized in calcium alginate beads and employed for production of erythromycin. Compared to conventional and washed mycelial fermentation, the average specific productivity of immobilised mycelia was superior.     

Development,persistence and regeneration of foraging ectomycorrhizal mycelial systems in soil microcosms

Development of extraradical mycelia of two strains each of Paxillus involutus and Suillus bovinus in ectomycorrhizal association with Pinus sylvestris seedlings was studied in two dimensions in non-sterile soil microcosms. There were significant inter- and intra-specific differences in extraradical mycelial growth and morphology. The mycelial systems of both strains of P. involutus were diffuse and extended more rapidly than those of S. bovinus. Depending on the strain, P. involutus mycelia were either highly plane filled, with high mass fractal dimension (a measure of space filling) or sparse, low mass fractal dimension systems. Older mycelial systems persisted as linear cords interlinking ectomycorrhizal tips. S. bovinus produced either a mycelium with a mixture of mycelial cords and diffuse fans that rapidly filled explorable area, or a predominately corded mycelium of minimal area cover. In the soil microcosms, mass fractal dimension and mycelial cover tended to increase with time, mycelia encountering litter having significantly greater values. Results are discussed in terms of the ecology of these fungi, their foraging activities and functional importance in forest ecosystems.     

Underground signals carried through common mycelial networks warn neighbouring plants of aphid attack

The roots of most land plants are colonised by mycorrhizal fungi that provide mineral nutrients in exchange for carbon. Here, we show that mycorrhizal mycelia can also act as a conduit for signalling between plants, acting as an early warning system for herbivore attack. Insect herbivory causes systemic changes in the production of plant volatiles, particularly methyl salicylate, making bean plants, Vicia faba, repellent to aphids but attractive to aphid enemies such as parasitoids. We demonstrate that these effects can also occur in aphid‐free plants but only when they are connected to aphid‐infested plants via a common mycorrhizal mycelial network. This underground messaging system allows neighbouring plants to invoke herbivore defences before attack. Our findings demonstrate that common mycorrhizal mycelial networks can determine the outcome of multitrophic interactions by communicating information on herbivore attack between plants, thereby influencing the behaviour of both herbivores and their natural enemies.     

Opposing developmental functions of Agrocybe aegerita galectin (AAL) during mycelia differentiation

Mycelia of basidiomycetes differentiating into fruiting body is a controlled developmental process, however the underlying molecular mechanism remains unknown. In previous work, a novel fungal Agrocybe aegerita galectin (AAL) was isolated from A. aegerita in our laboratory. AAL was shown to promote mycelial differentiation in A. aegerita and Auricularia polytricha, indicating that AAL might function as a conserved fruiting initiator during basidiomycete mycelia development. In the current work, we investigate the role of AAL in mycelia differentiation and fruiting body formation. First, the expression and localization of AAL in mycelia, primordium and fruiting body were assessed by Western blotting and immunohistochemistry. AAL was found to be ubiquitously expressed in the primordium and fruiting body but not in the mycelia. AAL facilitated mycelia congregation and promoted fruiting body production when AAL was applied on mycelia. At the same time, when AAL was spread on potato dextrose agar (PDA) medium prior to mycelia inoculation, mycelia exhibited slowed growth rates, resulting in mycelia cords formation and inhibition of fruiting body formation. The 5' regulatory sequence of aal was cloned by 'genome walking'. Here, we show that aal lack introns in the coding region and the upstream 740 bp sequence was characterized by the existence of core promoter elements, which included: two CCAAT boxes (-535/-280), a GC box (-145), a TATA box (-30) and a fungal leader intron within the 5' UTR. The identification of regulatory expression elements may provide an explanation to the stage-specific and high-level expression of aal during fruiting development.     

Plant Species Composition Effects on Belowground Properties and the Resistance and Resilience of the Soil Microflora to a Drying Disturbance

We hypothesised that plant species composition and richness would affect soil chemical and microbial community properties, and that these in turn would affect soil microbial resistance and resilience to an experimentally imposed drying disturbance. We performed a container experiment that manipulated the composition and species richness of common pasture plant species (Trifolium repens, Lolium perenne, and Plantago lanceolata) by growing them in monoculture, and in all the possible two and three-way combinations, along with an unplanted control soil. Experimental units were harvested at four different times over a 16-month period to determine the effect of plant community development and seasonal changes in temperature and moisture on belowground properties. Results showed that plant species composition influenced soil chemistry, soil microbial community properties and soil microbial resistance and resilience. Soil from planted treatments generally showed reduced soil microbial resistance to drying compared to unplanted control soils. Soils from under T. repens showed a higher resistance and resilience than the soils from under P. lanceolata, and a higher resistance than soils from under L. perenne. We suggest that differences across soils in either resource limitation or soil microbial community structure may be responsible for these results. Plant species richness rarely affected soil microbial community properties or soil microbial resistance and resilience, despite having some significant effects on plant community biomass and soil nitrogen contents in some harvests. The effect that treatments had for most variables differed between harvests, suggesting that results can be altered by the stage of plant community development or by extrinsic environmental factors that varied with harvest timing. These results in combination show that soil microbial resistance and resilience was affected by plant community composition, and the time of measurement, but was largely unrelated to plant species richness.     

Use of mycelia as paths for the isolation of contaminant‐degrading bacteria from soil

Mycelia of fungi and soil oomycetes have recently been found to act as effective paths boosting bacterial mobility and bioaccessibility of contaminants in vadose environments. In this study, we demonstrate that mycelia can be used for targeted separation and isolation of contaminant‐degrading bacteria from soil. In a ‘proof of concept’ study we developed a novel approach to isolate bacteria from contaminated soil using mycelia of the soil oomycete Pythium ultimum as translocation networks for bacteria and the polycyclic aromatic hydrocarbon naphthalene (NAPH) as selective carbon source. NAPH‐degrading bacterial isolates were affiliated with the genera Xanthomonas, Rhodococcus and Pseudomonas. Except for Rhodococcus the NAPH‐degrading isolates exhibited significant motility as observed in standard swarming and swimming motility assays. All steps of the isolation procedures were followed by cultivation‐independent terminal 16S rRNA gene terminal fragment length polymorphism (T‐RFLP) analysis. Interestingly, a high similarity (63%) between both the cultivable NAPH‐degrading migrant and the cultivable parent soil bacterial community profiles was observed. This suggests that mycelial networks generally confer mobility to native, contaminant‐degrading soil bacteria. Targeted, mycelia‐based dispersal hence may have high potential for the isolation of bacteria with biotechnologically useful properties.     

Ectomycorrhizal fungi and their enzymes in soils: is there enough evidence for their role as facultative soil saprotrophs?

Although ectomycorrhizal (ECM) fungi are generally regarded as dependent upon the supply of carbon from their plant hosts, some recent papers have postulated a role for these fungi in the saprotrophic acquisition of carbon from soil. This theory was mainly based on the increase in enzymatic activity during periods of low photosynthate supply from tree hosts and emergence of the theory has led to a question about the overall influence of saprotrophy by ECM fungi on soil carbon turnover. However, I argue here that there is still not enough evidence to confirm this proposed function. My argument is based on inference from several lines of observation and concern over several aspects of the past studies. First, ECM fungi mainly inhabit deeper soil horizons, in which the availability of carbon compounds with positive energetic value is low. Second, the ability of ECM fungi to produce ligninolytic enzymes and cellulases is much weaker than that of saprotrophic basidiomycetes. This is most apparent in the low copy abundance of corresponding genes in the sequenced genomes of ECM species Laccaria bicolor and Amanita bisporigenes compared to the saprotrophic species Galerina marginata. I offer alternative hypotheses to explain the past observations of increased enzyme activity during starvation periods. These include, the induction of autolytic processes in ECM fungal mycelia or an attack on the host tissues to support escape from a dying root and to allow for a search for new hosts.     

Enzyme Immunoassay of Herbicide Decomposition by Soil and Wood Decay Fungi

The effect of herbicide atrazine was studied on the growth and development of a number of soil and wood decay fungi: white-rot basidiomycetes (Cerrena maxima, Coriolopsis fulvocenerea, and Coriolus hirsutus), thermophilic micromycetes from self-heating grass composts (cellulolytic fungus Penicilliumsp. 13 and noncellulolytic ones Humicola lanuginosaspp. 5 and 12), and mesophilic phenol oxidase-producing micromycete Mycelia sterilia INBI 2-26. Detection of atrazine in liquid fungal cultures was performed by using the enzyme immune assay technique. Both stimulation (Humicola lanuginosa 5) and suppression (Humicola lanuginosa 12 and Penicillium sp. 13) of fungal growth with atrazine were observed on solid agar media. HyphomyceteMycelia sterilia INBI 2-26 was almost insensitive to the presence of atrazine. Neither of the thermophilic strains was capable of atrazine consumption in three-week cultivation. In contrast with that, active laccase producers Cerrena maxima, Coriolopsis fulvocenerea, and Coriolus hirsutus consumed up to 50% atrazine in 5-day cultivation in the presence of the xenobiotic and at least 80–92% in 40 days. Mycelia steriliaINBI 2-26, which also forms extracellular laccase, also consumed up to 70% atrazine in 17 days. The degree of atrazine consumption depended on the term of its addition to the fungal culture medium.     

Fruiting Body Formation from Regenerated Mycelium of Pleurotus ostreatus Protoplasts

Fruiting bodies were induced from mycelium regenerated from Pleurotus ostreatus protoplasts. Mycelia originated from protoplasts conformed to parental strain mycelia in morphology. Six strains selected at random from the dikaryotic regenerants were able to form normal fruiting bodies, yielding 18% more than the parent.     

Thermotolerant and thermophilic actinomycetes from soils of Mongolia desert steppe zone

In the actinomycete complexes of Mongolian desert soils, thermotolerant and thermophilic actinomycetes were found in high abundance, exceeding that of the mesophilic forms. Among the thermotolerant members of the order Actinomycetales, Streptomyces, Micromonospora, Actinomadura, and Streptosporangium species were most widespread in desert soils. Experiments with soil microcosms demonstrated that thermophilic actinomycetes in desert soils grew, developed, and formed mycelia of the length comparable to that of the mesophilic forms of actinomycetes. Molecular biological investigation of the samples of desert steppe soils by denaturing gradient gel electrophoresis (DGGE) and fluorescent in situ hybridization (FISH) revealed members of the phylum Actinobacteria. FISH analysis revealed that the biomass of the metabolically active mycelial actinobacteria in the prokaryotic community of Mongolian desert soils exceeded that of the unicellular Actinobacteria.     

Cyanide degradation by immobilised fungi

Summary Cyanide hydratase, which converts cyanide to formamide, was induced in mycelia of Stemphylium loti by growth in the presence of low concentrations of cyanide. Mycelia were immobilised by several methods. The most useful system was found to be treatment with flocculating agents. This technique is applicable to a wide range of easily isolated fungi that contain cyanide hydratase.     

Host plants and edaphic factors influence the distribution and diversity of ectomycorrhizal fungal fruiting bodies within rainforests from Tshopo,Democratic Republic of the Congo

Ectomycorrhizal fungi constitute an important component of forest ecosystems that enhances plant nutrition and resistance against stresses. Diversity of ectomycorrhizal (EcM) fungi is, however, affected by host plant diversity and soil heterogeneity. This study provides information about the influence of host plants and soil resources on the diversity of ectomycorrhizal fungal fruiting bodies from rainforests of the Democratic Republic of the Congo. Based on the presence of fungal fruiting bodies, significant differences in the number of ectomycorrhizal fungi species existed between forest stand types (p < 0.001). The most ectomycorrhizal species‐rich forest was the Gilbertiodendron dewevrei‐dominated forest (61 species). Of all 93 species of ectomycorrhizal fungi, 19 demonstrated a significant indicator value for particular forest stand types. Of all analysed edaphic factors, the percentage of silt particles was the most important parameter influencing EcM fungi host plant tree distribution. Both host trees and edaphic factors strongly affected the distribution and diversity of EcM fungi. EcM fungi may have developed differently their ability to successfully colonise root systems in relation to the availability of nutrients.     

替考游动放线菌发酵生产替考拉宁的动力学模型

根据丝状菌的生长机理和替考拉宁的发酵动力学特征提出了一个简化的形态学结构模型,并用于描述替考拉宁的发酵过程．模型将菌丝分为三种类型：具有生长活性的菌丝(G)、具有代谢活性的菌丝(N)和失活的菌丝(D)．菌丝G可因失去生长活性而转化为菌丝N,菌丝N可因失去代谢活性而转化为菌丝D．菌丝G与菌丝生长有关,而菌丝N则与替考拉宁的合成有关．该模型能较好地描述替考拉宁发酵过程、     

Bacteria associated with truffle‐fruiting bodies contribute to truffle aroma

Truffles, symbiotic fungi renown for the captivating aroma of their fruiting bodies, are colonized by a complex bacterial community of unknown function. We characterized the bacterial community of the white truffle Tuber borchii and tested the involvement of its microbiome in the production of sulphur‐containing volatiles. We found that sulphur‐containing volatiles such as thiophene derivatives, characteristic of T. borchii fruiting bodies, resulted from the biotransformation of non‐volatile precursor(s) into volatile compounds by bacteria. The bacterial community of T. borchii was dominated by α‐ and β‐Proteobacteria. Interestingly, all bacteria phyla/classes tested in this study were able to produce thiophene volatiles from T. borchii fruiting body extract, irrespective of their isolation source (truffle or other sources). This indicates that the ability to produce thiophene volatiles might be widespread among bacteria and possibly linked to primary metabolism. Treatment of fruiting bodies with antibacterial agents fully suppressed the production of thiophene volatiles while fungicides had no inhibitory effect. This suggests that during the sexual stage of truffles, thiophene volatiles are exclusively synthesized by bacteria and not by the truffle. At this stage, the origin of thiophenes precursor in T. borchii remains elusive and the involvement of yeasts or other bacteria cannot be excluded.     

Evaluation of plant extracts as an antagonist to mycelial growth of Mycosphaerella fijiensis morelet

Three plant extracts (rice husk, wood and bamboo) at different concentration were evaluated in vitro as an antagonist to mycelial growth of Mycosphaerella fijienesis on different culture media using spread plate and mycelia dry weight method. The plant extracts had significant effects on the mycelial growth of Mycosphaerella fijiensis. Rice husk extract at concentration of 1, 1.5, 2.5 and 5% completely inhibited the mycelia growth of M. fijiensis in malt extract broth (MEB) and at 2.5 and 5% on malt extract agar (MEA). Wood extract at concentration of 1 and 1.5% inhibited the mycelial growth of M. fijiensis and completely at concentration of 2.5 and 5% on MEA. Although complete inhibition was only observed at 5% concentration on MEA for bamboo extract, the evaluated plant extracts could be recommended for the control of M. fijiensis on a large-scale farming.