Total Mycelium Research Articles

Analysis of the emerging physical network in young mycelia

Filamentous fungi develop intricate hyphal networks that support mycelial foraging and transport of resources. These networks have been analyzed recently using graph theory, enabling the development of models that seek to predict functional traits. However, attention has focused mainly on mature colonies. Here, we report the extraction and analysis of the graph corresponding to Trichoderma atroviride mycelia only a few hours after conidia germination. To extract the graph for a given mycelium, a mosaic conformed of multiple bright-field, optical microscopy images is digitally processed using freely available software. The resulting graphs are characterized in terms of number of nodes and edges, average edge length, total mycelium length, hyphal growth unit, maximum edge length and mycelium diameter, for colonies between 8 h and 14 h after conidium germination. Our results show that the emerging hyphal network grows first by hyphal elongation and branching, and then it transitions to a stage where hyphal-hyphal interactions become significant. As a tangled hyphal network develops with decreasing hyphal mean length, the mycelium maintains long (∼2 mm) hyphae—a behavior that suggests a combination of aggregated and dispersed architectures to support foraging. Lastly, analysis of early network development in Podospora anserina reveals striking similarity with T. atroviride, suggesting common mechanisms during initial colony formation in filamentous fungi.

Deletion of the small GTPase rac1 in Trichoderma reesei provokes hyperbranching and impacts growth and cellulase production

BackgroundTrichoderma reesei is widely known for its enormous protein secretion capacity and as an industrially relevant producer of cellulases and hemicellulases. Over the last decades, rational strain engineering was applied to further enhance homologous and heterologous enzyme yields. The introduction of hyperbranching is believed to increase protein secretion, since most exocytosis is located at the hyphal apical tip. There are several genetic modifications which can cause hyperbranching, for example the deletion of the small Rho GTPase rac. Rac plays a crucial role in actin dynamics and is involved in polarisation of the cell during germination and apical extension of the hyphae.ResultsWe deleted rac1 in a T. reesei strain with an ectopically overexpressed endoglucanase, CEL12A, under Pcdna1 control. This deletion provoked a hyperbranching phenotype and strong apolar growth during germination and in mature hyphae. The strains displayed dichotomous branching and shorter total mycelium length with a larger hyphal diameter. Δrac1 strains exhibited a decreased radial growth on solid media. Biomass formation in liquid cultures was carbon source dependent; similar to the reference strain during growth on lactose, increased on d-glucose and slightly enhanced on cellulose. While extracellular cellulase activities remained at parental strain levels on d-glucose and cellulose, the specific activity on lactose cultures was increased up to three times at 72 h accompanied by an upregulation of transcription of the main cellulases. Although the morphology of the Δrac1 strains was considerably altered, the viscosity of the culture broth in fed-batch cultivations were not significantly different in comparison to the parental strain.ConclusionsDeletion of the small Rho GTPase rac1 changes the morphology of the hyphae and provokes hyperbranching without affecting viscosity, independent of the carbon source. In contrast, biomass formation and cellulase production are altered in a carbon source dependent manner in the Δrac1 strains.

Cultivation and medicinal properties of wild edible Pleurotus ostreatus of Tripura, Northeast India

Cultivation of edible mushrooms is one of the most economically usable processes for bioconversion of agro wastes for the production of protein-rich food with various medicinal values. The present investigation was focused to determine the most effective and suitable substrate for the cultivation of Pleurotus ostreatus considering biological efficiency and medicinal activities of fruiting bodies. Different parameters like mycelium running rate, development of fruiting bodies, cropping phase, productivity, biological efficiency and medicinal activities like antibacterial, antioxidant activities of this mushroom were evaluated. The total mycelium running, total primordial formation, complete fruit body formation and duration of cropping were dominant in PS substrate. Fruiting body size was bigger in SD substrate but higher productivity (19.6%) and biological efficiency (65.33%) was observed in PS substrate. Methanolic extracts of cultivated P. ostreatus on PS substrate showed higher antibacterial, free radical scavenging activity (74.26%), chelating effects on ferrous ion (91.11%), total phenol content (0.097 mg GAE/g) and flavonoids content (0.017 mg CE/g). The lowest EC50 values of cultivated P. ostreatus were found in PS substrate which indicated the stronger ability of antioxidant activity. The present study indicates that the types of used substrates affect biological efficiency and medicinal properties.

Microwave vacuum pyrolysis conversion of waste mushroom substrate into biochar for use as growth medium in mushroom cultivation

AbstractBACKGROUNDSpent mushroom substrate (SMS), largely produced as an agriculture waste from mushroom cultivation, was transformed into biochar via microwave vacuum pyrolysis under different ratios of SMS to microwave absorbent (1:1, 1:2, and 1:3). The biochar was then examined for its potential to be re‐used in mushroom cultivation as a growth medium added to conventional mushroom baglog (plastic bag with mushroom seeds and culture substrates containing rice straw, sawdust, lime and water), with emphasis on its ability to form mycelium – a fungus that grows into mushroom from its seeds.RESULTThe pyrolysis generated up to 36 wt% biochar yield with a large adsorption area (up to 215 m2 g‐1) and less water (4 wt%), indicating that many adsorption sites are available on which mushroom seeds, nutrient and water can be adsorbed onto in order to form mycelium (and subsequently mushroom). The biochar added to grow mushroom in baglog recorded a higher water retention percentage (up to 59%), a higher mycelium colonization length in 8 days (6.3 cm), coverage area (up to 259 cm2) and total mycelium growth volume (317 cm3), and resulted in a higher yield of mushroom (200 g month‐1) than that recorded for the conventional baglog without biochar (160 g month‐1).CONCLUSIONThe results indicated that biochar produced from SMS using microwave vacuum pyrolysis shows great potential in retaining water and nutrient that in turn promotes the formation of mycelium that leads to increased growth of mushroom in its cultivation. © 2018 Society of Chemical Industry

Morphological and physiological responses of the external mycelium of Rhizophagus intraradices to water stress

Most studies dealing with mycorrhizal associations and drought have focused on the plants, not on the fungi, and tolerance and adaptations of arbuscular mycorrhizal (AM) fungi to cope with water stress are virtually unknown. This study was conducted to assess how water stress directly affects an AM fungus isolate, particularly through morphological and physiological changes in the external mycelium. We used two-compartment pots separated by mesh and an air gap that allowed us to apply water stress treatments only to the external mycelium. Clover (Trifolium subterraneum L.) plants inoculated with Rhizophagus intraradices grew at high humidity until external mycorrhizal mycelium developed in the mycelium compartment. Then, we started three watering treatments: high (H, 70% of soil water holding capacity), low (L, 10%), and mixed watering (HLHL, 70-10-70-10%) only in the hyphal compartment. The HLHL treatment was rewetted once to 70% after 42days. We measured total mycelium length, hyphal length in diameter categories, respiration activity, and protoplasm fragmentation 42 and 76days after starting the treatments. Rhizophagus intraradices mycelium responded to water stress by reducing its length, maintaining larger diameter hyphae, and concentrating protoplasm activity in fragments in the HLHL and L treatments. In both water stress treatments, changes suggested a trade-off between avoiding desiccation and storing resources, and maintaining soil exploration and water uptake capacity.

Combining laser microdissection and RNA-seq to chart the transcriptional landscape of fungal development.

BackgroundDuring sexual development, filamentous ascomycetes form complex, three-dimensional fruiting bodies for the protection and dispersal of sexual spores. Fruiting bodies contain a number of cell types not found in vegetative mycelium, and these morphological differences are thought to be mediated by changes in gene expression. However, little is known about the spatial distribution of gene expression in fungal development. Here, we used laser microdissection (LM) and RNA-seq to determine gene expression patterns in young fruiting bodies (protoperithecia) and non-reproductive mycelia of the ascomycete Sordaria macrospora.ResultsQuantitative analysis showed major differences in the gene expression patterns between protoperithecia and total mycelium. Among the genes strongly up-regulated in protoperithecia were the pheromone precursor genes ppg1 and ppg2. The up-regulation was confirmed by fluorescence microscopy of egfp expression under the control of ppg1 regulatory sequences. RNA-seq analysis of protoperithecia from the sterile mutant pro1 showed that many genes that are differentially regulated in these structures are under the genetic control of transcription factor PRO1.ConclusionsWe have generated transcriptional profiles of young fungal sexual structures using a combination of LM and RNA-seq. This allowed a high spatial resolution and sensitivity, and yielded a detailed picture of gene expression during development. Our data revealed significant differences in gene expression between protoperithecia and non-reproductive mycelia, and showed that the transcription factor PRO1 is involved in the regulation of many genes expressed specifically in sexual structures. The LM/RNA-seq approach will also be relevant to other eukaryotic systems in which multicellular development is investigated.

Avaliação da interação micorrízica em cultivares de oliveira (Olea europea L.)

A maioria dos estudos com oliveira no Brasil e no mundo tem sido direcionada à produção e ao manejo. Apesar da importância para o crescimento vegetal e resistência a estresses diversos, não há estudos sobre a ocorrência de associação micorrízica em oliveira, no Brasil. O objetivo do presente trabalho foi avaliar a interação micorrízica em cultivares de oliveira na Fazenda Experimental de Maria da Fé - MG (FEMF - EPAMIG), a qual serve como ponto de partida na produção de inoculantes comerciais de fungos micorrízicos arbusculares para a cultura. Amostras de solo e de raízes de sete cultivares de oliveira foram coletadas para determinação do comprimento de micélio extrarradicular ativo e total e avaliação da percentagem e intensidade de colonização micorrízica, bem como da densidade e diversidade de esporos. Nas rizosferas das cultivares de oliveira, foram isoladas nove espécies de fungos micorrízicos: Acaulospora denticulata, Acaulospora scrobiculata, Acaulospora sp1, Acaulospora sp2, Entrophospora sp1, Gigaspora sp1, Glomus mosseae, Scutellospora pellucida e Scutellospora sp1. Os resultados comprovaram o micotrofismo da espécie. No entanto, não houve efeito das cultivares na distribuição dos propágulos de FMAs, os quais estiveram homogeneamente distribuídos nas diferentes rizosferas.

Characterization of main sulfur source of wood-degrading basidiomycetes by S K-edge X-ray absorption near edge spectroscopy (XANES)

The main wood degraders in aerobic terrestrial ecosystems belong to the white- and brown-rot fungi, where their biomass can be created on wood decay only. However, total sulfur (S) concentration in wood is very low and only little is known about the different sulfur compounds in wood today. Sulfur-starved brown-rot fungi Gloeophyllum trabeum and Oligoporus placenta were incubated on sterilized pine wood blocks whereas Lentinus cyathiformis and the white-rot fungi Trametes versicolor were incubated on sterilized beech wood blocks. After 19 weeks of incubation, the S oxidation status was analyzed in wood, in degraded wood, and in biomass of wood-degrading fungi by synchrotron based S K-edge XANES, and total S and sulfate were quantified. Total sulfur and sulfate content in pine wood blocks were approximately 50 and 1 μg g −1, respectively, while in beech wood approximately 100 and 20 μg g −1 were found, respectively. Sulfur in beech was dominated by sulfate-esters. In contrast, pine wood also contained larger amounts of reduced S. Three out of four selected fungi caused a reduction of the S oxidation state in wood from oxidized S (sulfate-ester, sulfate) to intermediate S (sulfonate, sulfoxide) or reduced S (thiols, e.g., proteins, peptides, enzyme cofactors). Only O. placenta shifted thiol to sulfonate. Growth experiments of these fungi on selective minimal media showed that in particular cysteine (thiol), sulfonates, and sulfate enhanced total mycelium growth. Consequently, wood-degrading fungi were able to utilize a large variety of different wood S sources for growth but preferentially transformed in vivo sulfate-esters and thiol into biomass structures.

Effects of different tillage system on arbuscular mycorrhizal fungal propagules and physical properties in a Mediterranean agroecosystem in central Chile

Arbuscular mycorrhizal (AM) fungi improve soil quality by increasing soil structure stability through the glomalin (glomalin related soil protein, GRSP) production, but diverse tillage systems can differentially affect AM activity and the consequential GRSP content in soil. The aim of this study was to evaluate the effect of no-tillage (NT) and conventional tillage (CT) on AM fungal propagules (spore density, total and active fungal hyphae), GRSP content, and its relationship with some physical–chemical soil properties in a Mollisol from Central Chile. For this study, two plots managed for 6 and 10 years under NT (NT6 and NT10), were compared with another plot maintained under CT management. In all cases a continuous spring wheat ( Triticum turgidum L.)–maize ( Zea mays L.) rotation was established. The number of mycorrhizal propagules, total soil carbon (T-C) and GRSP content in NT6 was higher compared to CT and NT10. This trend was also observed for water stable aggregates (WSA) and water drop penetration time. Significant relationships were found between total mycelium and GRSP ( r = 0.58, p < 0.05), GRSP and WSA ( r = 0.66, p < 0.01) and between GRSP and T-C ( r = 0.60, p < 0.05), suggesting an active role of AM fungi and GRSP on soil aggregation, particularly under NT6 management. In addition, the long-term NT management (NT10) produced a decrease in the parameters here assayed which suggest the application of one moderate plowing when parameters such as T-C and/or GRSP show a decrease in long-term programs of reduced or NT management applied in medium/heavy soils.

In vitro effect of Melaleuca alternifolia and Eucalyptus globulus essential oils on mycelia formation by oral Candida albicans strains

Several mechanisms can inhibit mycelium formation which is an essential step forCandida albicans virulence. In this study, two essential oils of Melaleuca alternifoliaand Eucalyptus globulus were tested for their ability to inhibit the mycelium formed on Lee medium by oral C. albicans. Lee medium was added with different concentrations of M. alternifolia essential oil ranging from 0.156 to 10 mg/ml and from 0.039 to 10 mg/ml for E. globulus. The results obtained showed that 5/17 of C.albicans strains were strongly mycelium producers, nine strains were moderately mycelium producers and three isolates were unable to form hyphae after 2 h of incubation in the same medium. M. alternifolia essential oil has an antimycelial activity against C. albicans isolates than E. globulus essential oil. In fact, only 1/2 minimum inhibitory concentration (MIC) (0.312 mg/ml) of M. alternifolia was able to inhibit total mycelium in C. albicans isolate while 2 MIC (0.312 mg/ml) of the second essential oil was necessary to inhibit germ tube formation in the same strain. Key words: Candida albicans, Melaleuca alternifolia, Eucalyptus globulus, mycelium, lee medium.

TILLAGE EFFECT ON SOIL ORGANIC MATTER, MYCORRHIZAL HYPHAE AND AGGREGATES IN A MEDITERRANEAN AGROECOSYSTEM

Arbuscular mycorrhizal fungi (AMF) and their product glomalin (GRSP) play a decisive role in the soil aggregation, affecting the carbon (C) dynamics in agroecosystems. Tillage affects the AMF activity and GRSP content, influencing the stability and the soil C forms as well. The aim of this study was to compare the effect of no tillage (NT) and conventional tillage (CT) on: i) arbuscular mycorrhizal hyphal length and GRSP content; ii) the nature of soil organic matter by means of physical fractionation (free particulate organic matter (fPOM); occluded particulate organic matter (oPOM) and mineral-associated soil organic matter (Mineral)), as well as chemical fractionation (fulvic acid, humic acid and humin), and iii) the relationships between AMF parameters, soil carbon and water stable aggregates (WSA) in a Mollisol of Central Chile managed for 6 years under NT and CT using a wheat-corn rotation. Higher values in the AMF hyphal length, GRSP and WSA in NT compared with CT were observed. Significant relationships were found between GRSP and WSA (r = 0.66, p < 0.01) and total mycelium and GRSP (r = 0.58, p< 0.05). The total carbon increased 44% under NT compared with CT. The chemical fractionation showed percentage greater than 95% for humim in both treatments. Physical fractionation indicates that the higher part of the SOC (89.4 - 95.1%) was associated with the mineral fraction.

Effect of culture medium composition on Trichoderma reesei’s morphology and cellulase production

The objective of this study was to determine how fungal morphology influences the volumetric cellulase productivity of Trichoderma reesei cultured in four media with lactose and lactobionic acid as fed-batch in a 7 L stirred tank bioreactor. The use of a cellulose–yeast extract culture medium yielded the highest enzyme production with a volumetric enzyme activity of 69.8 U L −1 h −1, and a maximum fungal biomass of 14.7 g L −1. These findings were associated with the following morphological characteristics of the fungus: total mycelia was 98% of total mean projected area, mean hyphae length of 10 mm, mean hyphae volume of 45.1 mm 3, mean hyphae diameter of 7.9 μm, number of branches 9, and number of tips per hypha 29. A positive correlation was found between the total mycelia, the number of tips and the volumetric enzyme productivity, indicating the weight of these variables on the enzyme productivity.

Propagules of arbuscular mycorrhizal fungi in a secondary dry forest of Oaxaca, Mexico

Plant cover loss due to changes in land use promotes a decrease in spore diversity of arbuscular mycorrhizal fungi (AMF), viable mycelium and, therefore, in AMF colonization, this has an influence in community diversity and, as a consequence, in its recovery. To evaluate different AMF propagules, nine plots in a tropical dry forest with secondary vegetation were selected: 0, 1, 7, 10, 14, 18, 22, 25, and 27 years after abandonment in Nizanda, Oaxaca, Mexico. The secondary vegetation with different stages of development is a consequence of slash and burn agriculture, and posterior abandonment. Soil samples (six per plot) were collected and percentage of AMF field colonization, extrarradical mycelium, viable spore density, infectivity and most probable number (MPN) ofAMF propagules were quantified through a bioassay. Means for field colonization ranged between 40% and 70%, mean of total mycelium length was 15.7 +/- 1.88 mg(-1) dry soil, with significant differences between plots; however, more than 40% of extracted mycelium was not viable, between 60 and 456 spores in 100 g of dry soil were recorded, but more than 64% showed some kind of damage. Infectivity values fluctuated between 20% and 50%, while MPN showed a mean value of 85.42 +/- 44.17 propagules (100 g dry soil). We conclude that secondary communities generated by elimination of vegetation with agricultural purposes in a dry forest in Nizanda do not show elimination of propagules, probably as a consequence of the low input agriculture practices in this area, which may encourage natural regeneration.

Transcriptional Profiles of the Human Pathogenic Fungus Paracoccidioides brasiliensis in Mycelium and Yeast Cells

Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, a disease that affects 10 million individuals in Latin America. This report depicts the results of the analysis of 6,022 assembled groups from mycelium and yeast phase expressed sequence tags, covering about 80% of the estimated genome of this dimorphic, thermo-regulated fungus. The data provide a comprehensive view of the fungal metabolism, including overexpressed transcripts, stage-specific genes, and also those that are up- or down-regulated as assessed by in silico electronic subtraction and cDNA microarrays. Also, a significant differential expression pattern in mycelium and yeast cells was detected, which was confirmed by Northern blot analysis, providing insights into differential metabolic adaptations. The overall transcriptome analysis provided information about sequences related to the cell cycle, stress response, drug resistance, and signal transduction pathways of the pathogen. Novel P. brasiliensis genes have been identified, probably corresponding to proteins that should be addressed as virulence factor candidates and potential new drug targets.

Fungal mycelium and decomposition of needle litter in three contrasting coniferous forests

The fungal mycelium ingrowth and the rates of mass loss and respiration of needle litter of Pinus pinea , Pinus laricio , Pinus sylvestris , and Abies alba were investigated, in three coniferous forests, over a 3-year period by means of a composite set of incubations. In the early stages, the fungal flora of the decomposing needles was dominated by dematiaceous hyphomycetes and coelomycetes. Basidiomycetes reached a peak after 6 months on pine needles, but were absent from the N-rich needles of A . alba . Soil fungi ( Penicillium , Trichoderma , Absidia , Mucor sp. pl.) became most frequent in later stages. At the end of the study period, the total mycelium amount showed the lowest values in all pine needles incubated in the P . laricio forest and the highest ones in P . pinea needles incubated in the P . pinea forest. In all data sets, as in data for boreal forests examined for comparison, the concentration of litter fungal mycelium versus litter mass loss followed a common exponential model. However, in later stages, the amount of litter fungal mycelium was very close to that of the humus at the incubation site, thus supporting the hypothesis of a logistic growth pattern. Respiration rates of decomposing litters varied with season and decreased with litter age to values close to those of the humus at the incubation site. Respiration of water-saturated litter was negatively correlated with the total mycelium concentration, and this was consistent with the observation that in far-decomposed litter only a minor fraction of the total mycelium is alive.

Improved isolation of nucleic acids from basidiomycete fungi.

BioTechniquesVol. 27, No. 3 BenchmarksOpen AccessImproved Isolation of Nucleic Acids from Basidiomycete FungiPetr Baldrian, Jiří Gabriel & Martin PospíšekPetr Baldrian*Address correspondence to Petr Baldrian, Institute of Microbiology AS CR, Vídeňská 1083, Prague 4, 142 20 Czech Republic. Internet: E-mail Address: baldrian@biomed.cas.czInstitute of Microbiology AS CR, Prague, Czech RepublicSearch for more papers by this author, Jiří GabrielInstitute of Microbiology AS CR, Prague, Czech RepublicSearch for more papers by this author & Martin PospíšekInstitute of Microbiology AS CR, Prague, Czech RepublicSearch for more papers by this authorPublished Online:22 Aug 2018https://doi.org/10.2144/99273bm12AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInRedditEmail FiguresReferencesRelatedDetailsCited ByCharacteristics and breeding of a new cultivar of Pleurotus ostreatus that is tolerant to envirochangesJournal of Mushroom, Vol. 14, No. 2Characterization of a new commercial strain 'Mongdol' by intra-specific hyphal anastomosis in Pleurotus ostreatusJournal of Mushroom, Vol. 13, No. 3Characteristics and breeding of a new oyster mushroom (Pleurotus ostreatus) variety 'Chunhwashim' by using cytoplasmic hybridJournal of Mushroom, Vol. 13, No. 2Characteristics and breeding of a new cultivar Pleurotus eryngii var. ferulae, 'Beesan No.1'Journal of Mushroom, Vol. 12, No. 1Characteristics and breeding of a new cultivar Pleurotus eryngii var. ferulae, 'Beesan No.2'Journal of Mushroom, Vol. 12, No. 1Characteristics and breeding of a new multi-generation oyster mushroom (Pleurotus ostreatus) variety 'Dagul'Journal of Mushroom, Vol. 11, No. 3Characteristics and breeding of a new cultivar Pleurotus eryngii, SeolsongJournal of Mushroom, Vol. 11, No. 2A simple extraction method suitable for PCR-based analysis of plant, fungal, and bacterial DNA3 September 2012 | Plant Molecular Biology Reporter, Vol. 22, No. 1A RAPID AND EFFECTIVE METHOD FOR TOTAL RNA EXTRACTION FROM CONIDIA AND MYCELIUM OF SEPTORIA TRITICI19 January 2011 | Journal of Rapid Methods & Automation in Microbiology, Vol. 11, No. 1 Vol. 27, No. 3 Follow us on social media for the latest updates Metrics Downloaded 166 times History Published online 22 August 2018 Published in print September 1999 Information© 2018 Author(s)PDF download

Effect of cultural conditions on the growth and amylolytic enzyme production by rhizopus oryzae

Rhizopus oryzae achieved a peak amylase production within 6 days of culture for starch yeast extract (SYE) medium and 8 days for yeast extract (YE) medium through the 20 days period of incubation, Maximum amylase activity by the fungus occurred prior to maximum production of mycelial biomass both in the SYE and YE media. Production of amylase was not related to total mycelium produced but was directly related to the type of carbon source in the medium. Starch and glucose were the best carbon sources for amylase production whereas maximum mycelial biomass was recorded in the medium containing sucrose as the sole carbon source. The maximum mycelial biomass and amylase activity were recorded at 30°C and pH 6. The fungus as a prolific amylase producer could be of industrial use in some fermentation processes.

Mycelial distribution in rice Koji

Mycelial distribution of Aspergillus oryzae in rice koji was measured to elucidate the steric growth mode in the solid-state culture. Mycelial density showed a exponential distribution against the distance from the surface of rice koji. On the basis of this phenomenon, mycelial distribution was expressed by a mathematical model and total mycelia were shown by the following equation: Y t= ac∫e b( R− r) r 2d r+ Y s where Y t is the total mycelia in koji, the first term in right side is the mycelia in the inner part of rice grain and Y s is the surface mycelia. The variable r is the distance from the center of the koji, R is the radius of the koji, and a, b, and c are parameters. The values of each parameter were obtained by the least squares method using the experimental data and the distribution of mycelia both in the surface and in the matrix of rice grain was shown quantitatively. The steric growth mode of fungi in rice grain was shown using these techniques. The mycelial distribution and enzyme composition in rice koji made in sake factories were examined and the results were analyzed by a principal component analysis. The results suggested that when the degree of mycelial penetration is low the activities of acid protease and acid carboxypeptidase are high.

DEVELOPMENT OF TOTAL AND VIABLE EXTRARADICAL MYCELIUM IN THE VESICULAR–ARBUSCULAR MYCORRHIZAL FUNGUS GLOMUS CLARUM NICOL. &amp; SCHENCK

SummaryClover (Trifolium repens L.) plants were inoculated with the vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus clarum Nicol. &amp; Schenck in three experiments performed in similar environmental conditions. Extra radical mycelium was separated from soil by the membrane filter technique and its total length was measured; viable amounts were assessed after staining with the fluorescent dye fluorescein diacetate (FDA). Total mycelium increased steadily, and reached its maximum length 8 weeks after inoculation, unlike viability rate which decreased, from an initial value of about 100% to less than 15% after a period of 5 to 8 weeks. Consequently, the length of viable mycelium decreased after the first weeks following inoculation. The viability of extra radical mycelium may be an important factor influencing nutrient uptake and translocation by the VAM fungus.

Long-term decomposition of barley straw: Chemical changes and ingrowth of fungal mycelium

Mass loss of barley straw exposed at 10 cm depth in an unfertilized field plot was followed for 2 yr. Organic-chemical changes in the decomposing straw were also followed as well as the ingrowth of flourescein-diacetate-active (FDA) fungal mycelium and total mycelium. Mass loss was faster during the first year than in the second. Concentration of total solubles decreased initially to a low but fairly constant level which was maintained for 2 yr. Total solid polysaccharides increased initially, but began to decompose after about 200 days, while sulfuric-acid lignin, which also increased initially, later began to decompose slightly. The amount of FDA-active fungal mycelium remained at a low and constant level for the 2 yr while total fungal biomass started to increase after the first winter and continued for the rest of the investigation. Within 3 weeks about 30% of the N had been leached from the straw and after the first winter about 50% of the N was released. After that a net uptake took place and after 2 yr the total net release was about 25%. The relative amount of N increased continuously after the first winter and was linear to mass loss.