Vegetative Growth Of Mycelium Research Articles

Surface properties-dependent antifungal activity of silver nanoparticles

Silver nanoparticles (AgNPs) exhibit unusual biocidal properties thanks to which they find a wide range of applications in diverse fields of science and industry. Numerous research studies have been devoted to the bactericidal properties of AgNPs while less attention has been focused on their fungicidal activity. Our studies were therefore oriented toward determining the impact of AgNPs characterized by different physicochemical properties on Fusarium avenaceum and Fusarium equiseti. The main hypothesis assumed that the fungicidal properties of AgNPs characterized by comparable morphology can be shaped by stabilizing agent molecules adsorbed on nanoparticle surfaces. Two types of AgNPs were prepared by the reduction of silver ions with sodium borohydride (SB) in the presence of trisodium citrate (TC) or cysteamine hydrochloride (CH). Both types of AgNPs exhibited a quasi-spherical shape. Citrate-stabilized AgNPs (TCSB-AgNPs) of an average size of 15 ± 4 nm were negatively charged. Smaller (12 ± 4 nm), cysteamine-capped AgNPs (CHSB-AgNPs) were characterized by a positive surface charge and higher silver ion release profile. The phytopathogens were exposed to the AgNPs in three doses equal to 2.5, 5 and 10 mg L−1 over 24 and 240 h. Additionally, the impact of silver ions delivered in the form of silver nitrate and the stabilizing agents of AgNPs on the fungi was also investigated. The response of phytopathogens to these treatments was evaluated by determining mycelial growth, sporulation and changes in the cell morphology. The results of our studies showed that CHSB-AgNPs, especially at a concentration of 10 mg L−1, strongly limited the vegetative mycelium growth of both species for short and long treatment times. The cell imaging revealed that CHSB-AgNPs damaged the conidia membranes and penetrated into the cells, while TCSB-AgNPs were deposited on their surface. The fungistatic (lethal) effect was demonstrated only for silver ions at the highest concentration for the F. equiseti species in the 240 h treatment. The number of spores of both Fusarium species was significantly reduced independently of the type of silver compounds used. Generally, it was found that the positively charged CHSB-AgNPs were more fungicidal than negatively charged TCSB-AgNPs. Thereby, it was established that the stabilizing agents of AgNPs and surface charge play a crucial role in the shaping of their fungicidal properties.

Effect of Bacterial Strains Isolated from Stored Shiitake (Lentinula edodes) on Mushroom Biodeterioration and Mycelial Growth

Shiitake (Lentinula edodes) is a fungus that attracts the attention of consumers and researchers due to its flavour and bioactive compounds with biological activities. However, it swiftly loses quality because of its short shelf life. The present work evaluated the shelf life of cultivated shiitake carpophores with a weekly monitoring of the physico-chemical, microbiological, and sensory parameters under three different storage conditions. To establish the mycopathogenicity of fruitbody-inhabiting bacterial microbiota, 48 strains were isolated from shiitake throughout its storage time and subsequently inoculated on cap cuticles and slices. Additionally, an antibiogram of these bacterial strains against shiitake mycelium was performed. Shiitake had a total microbial load of 5 log cfu/g, composed mainly of Pseudomonas genus, followed by Enterobacteriaceae family, and moulds and yeasts. Among the 48 bacterial strains identified, 18 belonged to the Enterobacteriaceae family and 21 to the Pseudomonas genus. The biodeterioration capacity of the isolated strains increased throughout the conservation period, with slices being more damaged than cap cuticles. We observed a mycopathogenic behaviour of Burkholderia sp., Ewingella americana, Serratia sp., Microbacterium sp. and Rahnella sp. strains, although only the latter highly inhibited shiitake vegetative mycelium growth.

Comparative transcriptome analysis identified candidate genes involved in mycelium browning in Lentinula edodes

BackgroundLentinula edodes is one of the most popular edible mushroom species in the world and contains useful medicinal components, such as lentinan. The light-induced formation of brown film on the vegetative mycelial tissues of L. edodes is an important process for ensuring the quantity and quality of this edible mushroom. To understand the molecular mechanisms underlying this critical developmental process in L. edodes, we characterized the morphological phenotypic changes in a strain, Chamaram, associated with abnormal brown film formation and compared its genome-wide transcriptional features.ResultsIn the present study, we performed genome-wide transcriptome analyses of different vegetative mycelium growth phenotypes, namely, early white, normal brown, and defective dark yellow partial brown films phenotypes which were exposed to different light conditions. The analysis revealed the identification of clusters of genes specific to the light-induced brown film phenotypes. These genes were significantly associated with light sensing via photoreceptors such as FMN- and FAD-bindings, signal transduction by kinases and GPCRs, melanogenesis via activation of tyrosinases, and cell wall degradation by glucanases, chitinases, and laccases, which suggests these processes are involved in the formation of mycelial browning in L. edodes. Interestingly, hydrophobin genes such as SC1 and SC3 exhibited divergent expression levels in the normal and abnormal brown mycelial films, indicating the ability of these genes to act in fruiting body initiation and formation of dikaryotic mycelia. Furthermore, we identified the up-regulation of glycoside hydrolase domain-containing genes in the normal brown film but not in the abnormal film phenotype, suggesting that cell wall degradation in the normal brown film phenotype is crucial in the developmental processes related to the initiation and formation of fruiting bodies.ConclusionsThis study systematically analysed the expression patterns of light-induced browning-related genes in L. edodes. Our findings provide information for further investigations of browning formation mechanisms in L. edodes and a foundation for future L. edodes breeding.

INFLUENCE OF SOME TREATMENTS ON DATE PALM FROND AND IT USAGE TO PREPARING COMPOST FOR WHITE BUTTON AGARICUS BISPORUS GROWTH

This study was conducted on Agriculture college of Abu-Grab/ Baghdad as a replacement location of Anbar University during 2015 / 2016 season to study the effects of Date palm frond incubation 30 days after soaking in solution of 5% Urea or 3.3% Ammonium hydroxide before using it to preparing a compost, and its effect on mycelium growth rate on solid medium, matt on liquid medium and protein content, and to study complete over growth time on compost media. Agaricus bisporus 169 strain and its spawn obtained from Organic Farming Project Belonging to Agriculture Researches Office / Agriculture Ministry. Simple experiments according to completely Randomized Design (CRD) with 3 replicates and 5 experimental units for each treatment .Genstat program was used to analyses all data and means tested by Least Significant Difference at 0.05 level. Results showed that, all composts prepared by usage partial from Date palm frond soaked in NH4OH solution increased vegetative growth of mycelium . Treatments of 75% wheat straw + 25% date palm frond and 50% wheat straw + 50% date palm frond given faster growth rat were 2.6 and 2.56 cm per day, while treatments of 75% wheat straw + 25% date palm frond and 50% wheat straw + 50% date palm frond soaked in Urea solution increased 2.5 and 2.53 cm day-1 respectively and increased protein content significantly (P.L. 0.05) were 24.30% and 26.25% respectively, when control treatment given 2.0 cm day-1, 0.15 g dry weight of biomass and 18.75% protein content respectively. On other hand compost from 50% wheat straw + 50% date palm frond soaked in water before incubation, 75% wheat straw + 25% date palm frond without treatment, 50% wheat straw + 50% date palm frond and 70% wheat straw + 25% date palm frond soaked in NH4OH reduced period of mycelia overgrowth on compost to 30.66 , 31.0 , 31.66 and 32.0 days respectively , while the control recorded 47.0 days.

Bioactivity of MWCNT in Conidia of Entomopathogenic Fungus Isaria fumosorosea

The bioactivity of three kinds of multi-walled carbon nanotubes (MWCNT) towards the conidia of entomopathogenic fungus Isaria fumosorosea was examined in an in vitro study. Commercial—raw and functionalized—carboxylated MWCNT were applied. A fungal conidia suspension was placed in contact with dispersed MWCNT over different time-periods. After contact with the nanomaterial, the conidia were cultured on dishes and both the linear vegetative mycelium growth and the sporulation and germination of the spores derived from the culture were investigated. Also, the pathogenicity of the conidia after contact with MWCNT was examined in relation to test larvae. No fungistatic activity of MWCNT relative to I. fumosorosea conidia was demonstrated. Conidia contact with MWCNT resulted in the following changes in vital processes in the subsequent culture compared to the control standard culture: (1) raw MWCNT limited mycelium inoculation, but the growth rate observed later in the log-phase was more intense; (2) after 24-h conidia contact with all MWCNT types, the mycelium sporulated the most intensively; longer contact resulted in sporulation process limitation. Germination of conidia after contact with the MWCNT was not significantly modified. Raw MWCNT potentiated conidia pathogenicity towards test insects. It was observed that carboxylation of MWCNT reduces the bioactivity of this nanomaterial towards the investigated conidia.

The physiological effects of multi-walled carbon nanotubes (MWCNTs) on conidia and the development of the entomopathogenic fungus, Metarhizium anisopliae (Metsch.) Sorok

The aim of the study was an in vitro evaluation of the effect of MWCNTs on the conidia of two strains of entomopathogenic fungus, Metarhizium anisopliae. The study made use of water suspensions of MWCNTs (concentration ∼ 3 mg·mL−1) made from commercial nanotubes and centrifuged. The conidia were placed in contact with nanotubes for 240 h. An assessment of MWCNT influence on conidia was performed after 1, 24, 72 and 240 h and focused on the linear growth of vegetative mycelium derived from these conidia, mycelium sporulation in subcultures and pathogenicity. Using TEM imaging, it was demonstrated that carbon nanotubes are able to damage cell membranes of the examined fungi conidia. However, the absence was noted of a significantly fungistatic effect of both MWCNT suspensions on the examined strains with respect to the physiological features in question. The increase in vegetative mycelium effected by spores after contact with MWCNTs was characterized by a slight modification in relation to the control. There was no strong trend (inhibition - stimulation), in relation to the effect of the tested suspension of carbon nanotubes, on the development of the vegetative mycelium in in vitro culture. Sporulation of the mycelium after completion of the culture only occurred in one case (strain Ma73F and culture of spores after 24-h contact with MWCNTs) significantly more intensely than in the controls. With respect to pathogenicity for test insects compared to the control strain, Ma73F spores grown from the longest contact with nanotubes suspensions performed significantly better. On the basis of the calculated of mycelium index growth rates and the time of death of the test insects (LT50), it was found that the adverse effects of water suspension MWCNTs on the spores of M. anisopliae were applied after a short contact with biological material. This indicates unfavorable physical rather than chemical effects on the tested cell. Over time, nanotube aggregation in water suspensions led to changes in their influence on the cells under examination.

Constructing a new integrated genetic linkage map and mapping quantitative trait loci for vegetative mycelium growth rate in Lentinula edodes

The most saturated linkage map for Lentinula edodes to date was constructed based on a monokaryotic population of 146 single spore isolates (SSIs) using sequence-related amplified polymorphism (SRAP), target region amplification polymorphism (TRAP), insertion–deletion (InDel) markers, and the mating-type loci. Five hundred and twenty-four markers were located on 13 linkage groups (LGs). The map spanned a total length of 1006.1 cM, with an average marker spacing of 2.0 cM. Quantitative trait loci (QTLs) mapping was utilized to uncover the loci regulating and controlling the vegetative mycelium growth rate on various synthetic media, and complex medium for commercial cultivation of L. edodes. Two and 13 putative QTLs, identified respectively in the monokaryotic population and two testcross dikaryotic populations, were mapped on seven different LGs. Several vegetative mycelium growth rate-related QTLs uncovered here were clustered on LG4 (Qmgr1, Qdgr1, Qdgr2 and Qdgr9) and LG6 (Qdgr3, Qdgr4 and Qdgr5), implying the presence of main genomic areas responsible for growth rate regulation and control. The QTL hotspot region on LG4 was found to be in close proximity to the region containing the mating-type A (MAT-A) locus. Moreover, Qdgr2 on LG4 was detected on different media, contributing 8.07 %–23.71 % of the phenotypic variation. The present study provides essential information for QTL mapping and marker-assisted selection (MAS) in L. edodes.

Characterization of the aap1 gene of Agaricus bisporus, a homolog of the yeast YAP1

The structure, homologies, polymorphism and expression profiles of a new gene, aap1, have been studied for precisely characterizing it and defining its putative involvement in thermo-tolerance of both vegetative mycelium growth and sporophore differentiation. Sequence polymorphism was analyzed in 3 homokaryons of A. bisporus and 24 strains having different abilities for mycelial growth at temperatures above 30°C and for producing mature fruiting bodies at 25°C. The level of gene expression was measured by real-time PCR both in vegetative mycelium after transfer from 25 to 32°C and in primordia and fruiting bodies produced during cultures at 17 or 25°C. The results indicated that aap1 gene belong to a new subfamily of the yeast YAP1 homologs. It is not a dominant contributor to the thermo-tolerance of A. bisporus, but the protein it encodes may be involved as an overall stress resistance transcription factor. The way Aap1 senses redox level differs from that of AP-1-like transcription factor Yap1.

Effect of Coal Ash on Growth and Metal Uptake by Some Selected Ectomycorrhizal Fungi in vitro

Six isolates of ectomycorrhizal fungi namely, Laccaria fraterna(EM-1083), Pisolithus tinctorius (EM-1081), Pisolithus tinctorius (EM-1290), Pisolithus tinctorius (EM-1293), Scleroderma verucosum (EM-1283), and Scleroderma cepa (EM-1233), were grown on three variants of coal ash, namely electrostatically precipitated (ESP) ash, pond ash, and bottom ash moistened with Modified Melin-Norkans (MMN) medium in vitro. The colony diameter reflected the growth of the isolates on the coal ash. Metal accumulation in the mycelia was assayed by atomic absorption spectrophotometry. Six metals, namely aluminum, cadmium, chromium, iron, lead, and nickel, were selected on the basis of their abundance in coal ash and toxicity potential for the present work. Growth of vegetative mycelium on fly ash variants and metal accumulation data indicated that Pisolithus tinctorius (EM-1290) was the most tolerant among the isolates tested for most of the metals. Since this isolate is known to be mycorrhizal with Eucalyptus, it could be used for the reclamation of coal ash over burdened sites.

Genet distribution of sporocarps and ectomycorrhizas of Suillus pictus in a Japanese white pine plantation

Summary • Spatial distribution and biomass of genets of sporocarps and ectomycorrhizas of Suillus pictus were studied in a plot of 20 × 24 m established in a Pinus pentaphylla var. himekomatsu plantation. • The biomass of S. pictus ectomycorrhizas was evaluated based on morphotypes, and genets were identified based on the inter-simple sequence repeat (ISSR) polymorphism analysis. • Suillus pictus was one of the dominant ectomycorrhizal fungal species in both the sporocarp and ectomycorrhizal communities in the study plot. Four genets were identified from sporocarps and these coincided with those identified from ectomycorrhizas. Sporocarps of each S. pictus genet occurred separately from those of other genets. Spatial distributions of ectomycorrhizas of each genet were wider than those of sporocarps. The largest genet occupied c. 54% of the plot, and the area of each genet differed considerably. • Vegetative growth of mycelia is assumed to play a more important role in the propagation of S. pictus than colonization from spores because expansions of all the four genets ranged from 25 to 30 m and no small genets were found in this plot.

Synthesis and antifungal activity of novel bisdithiocarbamate derivatives of carbohydrates against Fusarium oxysporum f. sp. lini.

Novel carbamic esters possessing a carbohydrate moiety derived from glycerol or D-glucose with two N,N-diethyldithiocarbamoyl groups and a series of bisdithiocarbamic esters having a ketone or an alkyl ester have been synthesized. The in vitro activity of these new compounds was evaluated against Fusarium oxysporum f. sp. lini. Some of the compounds [bis[1,3-S-(N,N-diethyldithiocarbamoyl)]-1, 3-dideoxyglycerol) and diethyl N,N'-(1,3-dideoxyglycer-1, 3-diyl)bis(dithiocarbamate)] were more active for inhibiting vegetative mycelium growth than, respectively, the commercial N, N-diethyldithiocarbamic acid sodium salt and Maneb. The structure activity of these new compounds is discussed.

Growth and mycelial strand production of Rigidoporus lignosus with various nitrogen and carbon sources

Growth and differentiation of mycelial strands in Rigidoporus lignosus have been shown to depend on suitable combinations of the pH of the media and the nature of the nitrogen and carbon sources. Amino acids as sole nitrogen sources gave rise to vegetative mycelium. At pH 4.5, growth and mycelial strand differentiation required asparagine, as the fungus failed to grow in the absence of this amino acid. However, at pH 6, differentiation of strands occurred appreciably in asparagine-deficient media, suggesting a close balance between pH and amino acid requirements. Ammonium was required for strand differentiation, while nitrate, as a sole nitrogen source, maintained the fungus undifferentiated. Of the carbohydrates tested, only glucose, fructose and mannose supported strand differentiation. Starch was found to be particularly effective in promoting growth of vegetative mycelium. Strand differentiation required more specific conditions than growth of the vegetative mycelium.

Production and Transformation of Conidia ofVenturia inaequalis

High yields of conidia of Venturia inaequalis were produced from either mycelial fragments or conidia on cellophane-covered surfaces of agar media incubated under continuous near-ultraviolet light. Optimal conditions required a cellophane-covered surface of potato-dextrose agar in combination with light and incubation for 1 wk. The procedure represents a convenient techique for the mass-production of clonal and sterile V. inaequalis conidia. Conidia were biolistically transformed to hygromycin B resistance with a plasmid (pOHT) containing a bacterial phosphotransferase gene spliced between regulatory elements from Aspergillus nidulans. Southern hybridization analysis showed that the plasmid was incorporated into heterologous regions of the genome. Hygromycin B-resistant transformants were mitotically stable during nonselective propagation. The heterologous gene conferring hygromycin B resistance was expressed during early stages of conidia germination and during vegetative growth of mycelium

Polyamines and the Phorogenesis of Mucorales

Reyna-lopez, G. and Ruiz-Herrera, J. 1993. Polyamines and the phorogenesis of mucorales. Experimental Mycology 17, 79-89. Appearance of sporangiophore primordia of Mucor rouxii and Phycomyces blakesleeanus was preceded by a transitory elevation in the levels of ornithine decarboxylase (ODC) and the polyamines putrescine and spermidine. If the ODC competitive inhibitor 1,4-diamino-2-butanone (DAB) was added before this time, it blocked the appearance of sporangiophores as well as the elevation of ODC and putrescine levels, but not those of spermidine, nor did it affect the growth of vegetative mycelium. If added later on, the drug did not prevent photogenesis, nor the differentiation of primordia into macro- or microphores. The effect of DAB on phorogenesis could be counteracted by putrescine (but not by spermidine) and by 5-azacytidine. It is suggested that polyamines are necessary to trigger the differentiation of some vegetative hyphae into sporangiophore primordia, probably affecting the expression of specific genes through a process involving DNA hypomethylation.

Deamplification and deletion of amplified DNA in Streptomyces lividans and S. fradiae.

Streptomyces lividans arginine auxotrophs which show amplification of a 5.7-kb DNA sequence, arose at a very high frequency, varying from 10% to 25% of Cmls spores. The amplifiable DNA sequence was shown to be stable over many generations. However, treatment of Cmls arg mutants with subinhibitory concentrations of antibiotics such as spectinomycin, streptomycin, chloramphenicol, thiostrepton and kanamycin, either during sporulation or during vegetative growth of mycelia, led to the deletion of the entire amplified DNA sequence, including the left and right junction sequences. Depending upon the method of antibiotic treatment a reduction in the copy number of the amplified DNA was also observed. This reduction in copy number apparently occurred without drastically affecting the basic structure of the amplifiable unit of DNA. This phenomenon appears to be universal since deamplification and deletion were observed also in S. fradiae. Further, spontaneous arg mutants arose at much lower frequency from spectinomycin-pretreated Cmls cells compared to untreated cells. These arg mutants isolated in the presence of spectinomycin did not show amplification of the 5.7-kb sequence. Southern blot analysis using the 5.7-kb probe showed that the entire DNA sequence homologous to the amplifiable DNA sequence had been deleted.

Sexuality, Distribution, and Dispersal of Heterobasidion annosum in Pine Plantations of Vermont

Mating experiments with monosporous isolates of H. annosum from red pine plantations in Vermont demonstrate that the fungus is heterothallic and unifactorial. Clamp connections are present in tissue isolates from basidiocarps and in mycelia formed from compatible matings. The distribution of clamp connections within these mycelia is irregular and the features of this character are described in detail. The incompatibility factor is multiallelic and 40 alleles were identified in our collections from 53 basidiocarps. These alleles were used as naturally-occurring genetic markers to examine the distribution of the fungus within plantations. The distributional data are used to contribute information regarding dispersal. The genetic evidence suggests that centers of infection within a plantation are not due to the extensive vegetative spread of single clones, but that multiple inoculations are common in the development of infection centers. Nevertheless, the vegetative growth of mycelium does occur across the root systems of adjacent trees.

Semi-continuous and Continuous Production of Aspergillus niger Spores in Submerged Liquid Culture

SUMMARY: Sporulation of Aspergillus niger was induced in continuous tower fermenters by restricting growth with nitrate limitation. Semi-continuous production of spores was achieved in a single-stage fermentation by alternating full-nutrient and nitrogen-deficient media to the culture. Continuous spore production was obtained in a two-stage fermentation system using the first stage for the growth of vegetative mycelium under optimum conditions and the second, larger, stage for sporulation induction in a constant nitrogen-deficient environment. Spores were produced from much simplified sporulation structures. Using a new sporulation index (Ω), which relates spore numbers produced to the quantity of substrate utilized, the average production efficiency of the two-stage continuous system was shown to be more than twice that of the semi-continuous production system. The tower fermenter was shown to be ideal for controlling organism morphology, thus providing conditions which allowed the development of continuous fungal sporulation.

Etude du polymorphisme intraclonal chez le Verticillium albo-atrum, forme à microsclérotes. I. La morphogénèse des thalles à partir des microconidies et ses variations

In vitro thallus regeneration from microconidia was studied to define the stages of morphogenesis of some Moroccan strains of Verticillium albo-atrum Reinke and Berthold, microsclerotial forms: germination of microconidia, initiation and growth of vegetative mycelium, formation of microconidia and microsclerotia. Wild-type phenotypic characteristics such as rate of radial growth, length of time for the appearance of microsclerotia, and morphological aspects of each strain were evaluated.The morphogenesis of clones obtained from isolated microconidia showed however wide variations in percentage of regeneration and in growth and phenotype of the thallus formed from the microconidia. These variations seem to depend in part on the age of the culture from which the microconidia are taken and generally involve modifications in the regeneration potentiality of microconidia and also the appearance of stable morphological variants of which the most frequent is the hyaline type forming no microsclerotia and covered with an abundant white cotton-like aerial mycelium. The consequences of these variations are considered from a phytopathological point of view and especially in relation to experimental inoculation techniques using microconidia.

Ultrastructure of polymorphic Mucor as observed by means of freeze-etching. I. Vegetative growth of mycelium and arthrospore formation in submerged and aerated cultures.

Ultrastructure of polymorphic Mucor as observed by means of freeze-etching. I. Vegetative growth of mycelium and arthrospore formation in submerged and aerated cultures.

Relation between the level of endogenous growth regulators and the differentiation of the fungusLentinus tigrinus studied in a synthetic medium

The fungusLentinus tigrinus was cultivated in a synthetic medium. During vegetative growth of mycelium and differentiation of fruiting bodies samples serving for determination of endogenous growth regulators were collected. The material was extracted with methanol, separated by chromatography and the isolated fractions were tested. Substances of auxin type were assayed with coleoptile segments of oat plants, gibberellins by measuring the hypocotyl growth in the lettuce and cytokinins from the degree of chlorophyll decomposition in the leaf segments of barley. Very low content of auxins was found in all phases of growth and differentiation of the fungus. The content of gibberellin substances was relatively high during the whole life of the fungus. The highest content is found in the vegetative mycelium and in the differentiated fruiting body, especially in the cap; it decreases during the differentiation of fruiting bodies. The content of cytokinins is equally high and the pattern of its change resembles that of the gibberellins. Its maximum is reached in young vegetative mycelium, it decreases when fruiting bodies are formed and when they are growing. Minimum is reached in the differentiated stalk, where also the amount of inhibitions is the highest. Experimental results show that during differentiation of fruiting bodies and their morphogenesis not only gibberellins and cytokinins are of importance, but also substances of an inhibitory character. A relatively high amounts of these substances was secreted into the cultivation medium. In a synthetic nutrient solution they may be easily demonstrated.