Mycelial Development Research Articles

Influence of temperature on decay, mycelium development and sporodochia production caused by Monilinia fructicola and M. laxa on stone fruits

Brown rot on peaches and nectarines caused by Monilinia spp. results in significant economic losses in Europe. Experiments were conducted to study the effects of temperature (0–33 °C) on the temporal dynamics of decay and mycelium development and the subsequent sporulation on peaches and nectarine fruit infected by M. laxa and M. fructicola. The rates of decay and mycelium development increased with temperature from 0 °C to 25 °C for both Monilinia species. At 0 °C, decay was faster for M. laxa (0.20 cm2 days−1) than for M. fructicola (0.07 cm2 days−1); indeed, M. laxa was able to develop mycelia and sporodochia, but M. fructicola was not. At 4 and 20 °C, there were no differences in decay and mycelia development between the two Monilinia species. When temperature increased from 25 to 33 °C, the rates of fungal decay and mycelium development decreased. At 30 and 33 °C, M. fructicola decayed faster (0.94 and 1.2 cm2 days−1, respectively) than M. laxa (0.78 and 0.74 cm2 days−1, respectively) and could develop mycelia and produce sporodochia, whereas M. laxa failed at 33 °C. These results indicated that M. fructicola is better adapted to high temperatures, whereas M. laxa is better adapted to low temperatures. These results can be used to predict the relative importance of the two species during the season at a given site and to improve management strategies for brown rot in areas where both species are present.

Analysis and description of the stages of Aspergillus fumigatus biofilm formation using scanning electron microscopy

BackgroundBiofilms are a highly structured consortia of microorganisms that adhere to a substrate and are encased within an extracellular matrix (ECM) that is produced by the organisms themselves. Aspergillus fumigatus is a biotechnological fungus that has a medical and phytopathogenic significance, and its biofilm occurs in both natural and artificial environments; therefore, studies on the stages observed in biofilm formation are of great significance due to the limited knowledge that exists on this specific topic and because there are multiple applications that are being carried out.ResultsGrowth curves were obtained from the soil and clinical isolates of the A. fumigatus biofilm formation. The optimal conditions for both of the isolates were inocula of 1 × 106 conidia/mL, incubated at 28 °C during 24 h; these showed stages similar to those described in classic microbial growth: the lag, exponential, and stationary phases. However, the biofilms formed at 37 °C were uneven.The A. fumigatus biofilm was similar regardless of the isolation source, but differences were presented according to the incubation temperature. The biofilm stages included the following: 1) adhesion to the plate surface (4 h), cell co-aggregation and exopolymeric substance (EPS) production; 2) conidial germination into hyphae (8-12 h), development, hyphal elongation, and expansion with channel formation (16-20 h); and 3) biofilm maturation as follows: mycelia development, hyphal layering networks, and channels formation, and high structural arrangement of the mycelia that included hyphal anastomosis and an extensive production of ECM (24 h); the ECM covered, surrounded and strengthened the mycelial arrangements, particular at 37 °C. In the clinical isolate, irregular fungal structures, such as microhyphae that are short and slender hyphae, occurred; 4) In cell dispersion, the soil isolate exhibited higher conidia than the clinical isolate, which had the capacity to germinate and generate new mycelia growth (24 h). In addition, we present images on the biofilm’s structural arrangement and chemical composition using fluorochromes to detect metabolic activity (FUNI) and mark molecules, such as chitin, DNA, mannose, glucose and proteins.ConclusionsTo our knowledge, this is the first time that, in vitro, scanning electronic microscopy (SEM) images of the stages of A. fumigatus biofilm formation have been presented with a particular emphasis on the high hyphal organization and in diverse ECM to observe biofilm maturation.

The use of sensory analysis in biotechnology of the cultivation of macromycetes

Sensory analysis is the most ancient and inexpensive method of assessing the quality of food products. Consumer demand for the fruit bodies of mushrooms is due to their unique taste and aroma. Profile methods of sensory analysis are used in quality control, for characterising the differences between food products and for determining the impact of various factors on the quality of the test product. The aim of this research is to study the influence of different types of substrates on the character and intensity of arom a of the dried fruit bodies of Pleurotus ostreatus (Jacq.: Fr.) Kumm. IBK–1535 using the sensory profile method. The substrates for the cultivation of mushrooms were selected from waste from the agricultural and wood processing industries: sunflower husks, wheat straw, waste from the cleaning of seed corn, and sawdust of deciduous trees and oak bark. The preparation and sterilization of substrates was performed according to standard techniques. During the process of cultivation we determined the culture-morphological indices of development of the mycelium: the duration of growth in the substrate, time of appearance of the primordia, the number of formed fruiting bodies of mushrooms, the average biomass of the fruiting bodies. We did not detect any significant differences between substrates in the growth rate of mycelia. The best culture-morphological indices of growth and development of mycelia were identified for the corn waste substrate. This substrate had the greatest number of primordia, while the lowest was for wheat straw. The mycelium of P. ostreatus IBK-1535 was white, fluffy, and denser on substrates of corn waste, sunflower husks and oak bark. The sensory profile analysis was performed according to ISO 6564:1885.1 g of dried fruiting bodies was crushed, placed in glass vials with stoppers and heated to +35…+40 °C for a better emission of volatile compounds. A five person degustation commission was trained to undertake the sensory analysis. First, using sensory analysis, the degustation commission determined the following descriptors of odour for the fruiting bodies of the fungi: mushroom, woody, grassy, sweet, sour. Then the intensity of the aroma of each sample was assessed on a five-point scale. The most characteristic mushroom aroma of the dried fruit bodies was obtained when oak bark was the substrate for cultivation. The samples of mushroom grown on sawdust and waste corn had a similar aroma. The samples obtained for sunflower husk and wheat straw had a slight mushroom aroma with grassy and sour notes. Thus, the use of the sensory profile method of analysis makes it possible to assess the degree of intensity of aroma of fruit bodies of higher edible mushrooms in relation to the conditions of their cultivation without having to use complicated instrumental methods of analysis. Moreover, sensory profile analysis can be used to monitor the odours and aromas of mushrooms, which are cultivated in artificial conditions, for the adjustment of the cultivation process and for conducting a rapid appraisal of the quality of mushroom products.

Conserved and divergent roles of the HOG1 kinase of Alternaria longipes in mycelial and conidial development, multi-stress responses, melanin production and pathogenicity

The protein kinase HOG1 in high osmolarity glycerol pathway is one of mitogen-activated protein kinases and plays an important role in fungi cellular responses to external stress and stimuli. In this study, AlHOG1, a yeast HOG1 homolog, was isolated from tobacco pathogenic fungus Alternaria longipes and its disrupted mutants were generated using homologous recombination. Compared with the wild-type strain, the mutants grew slower under Minimal-Media, produced less conidia on Potato-Dextrose-Agar and showed a retardation phenotype in conidial germination rate. Colony color observation indicated that AlHOG1 most likely negatively regulated melanin production under nutrients-deficient or osmotic stress. The same action mode of AlHOG1 on hyphal growth in response to certain carbon or nitrogen sources was speculated. Additionally, the disrupted strains were sensitive to osmotic and oxidative stress, and showed increased resistance to dicarboximide, phenylpyrrole and carbendazim fungicides. Meanwhile, results from the comparative analysis between the AlHOG1- and the AlHK1 (encoding a group III histidine kinase)-disrupted mutants showed that AlHOG1 mediated-pathway was partly regulated by the upstream AlHK1 kinase for cellular resistance to salts osmotic stress and that AlHK1 was a primary regulator for cellular sugar and fungicides stress adaptation and likely modulated both AlHOG1-mediated pathway and other unknown mechanisms. Noteworthily, AlHOG1 but not AlHK1 was confirmed to be associated with high concentration glycerol adaptation, which is the first report to our knowledge. Overall, our results indicated that AlHOG1 was involved in multiple physiological processes in A. longipes, including mycelial and conidial development, melanin production, nutrients sensing and multi-stress responses.

First report of Fusarium oxysporum species complex infection in zebrafish culturing system

Fusarium oxysporum species complex (FOSC) is a highly diverse fungus. Recently, F.oxysporum infection was identified from zebrafish (Danio rerio) culturing system in Korea. Initially, a rapid whitish smudge was appeared in the water with the fungal blooming on walls of fish tanks. Microscopic studies were conducted on fungal hyphae, colony pigmentation and chlamydospore formation and the presence of macro- and microspores confirmed that the isolated fungus as F.oxysporum. Furthermore, isolated F.oxysporum was confirmed by internal transcribed spacer sequencing which matched (100%) to nine F.oxysporum sequences available in GenBank. Experimental hypodermic injection of F.oxysporum into adult zebrafish showed the development of fungal mycelium and pathogenicity similar to signs observed. Histopathologic results revealed a presence of F.oxysporum hyphae in zebrafish muscle. Fusarium oxysporum growth was increased with sea salt in a concentration-dependent manner. Antifungal susceptibility results revealed that F.oxysporum is resistant to copper sulphate (up to 200μgmL-1 ) and sensitive to nystatin (up to 40μgmL-1 ). This is the first report of FOSC from zebrafish culture system, suggesting it appears as an emerging pathogen, thus posing a significant risk on zebrafish facilities in the world.

The novel fungal-specific gene FUG1 has a role in pathogenicity and fumonisin biosynthesis in Fusarium verticillioides.

Fusarium verticillioides is a globally important pathogen of maize, capable of causing severe yield reductions and economic losses. In addition, F. verticillioides produces toxic secondary metabolites during kernel colonization that pose significant threats to human and animal health. Fusarium verticillioides and other plant-pathogenic fungi possess a large number of genes with no known or predicted function, some of which could encode novel virulence factors or antifungal targets. In this study, we identified and characterized the novel gene FUG1 (Fungal Unknown Gene 1) in F. verticillioides through functional genetics. Deletion of FUG1 impaired maize kernel colonization and fumonisin biosynthesis. In addition, deletion of FUG1 increased sensitivity to the antimicrobial compound 2-benzoxazolinone and to hydrogen peroxide, which indicates that FUG1 may play a role in mitigating stresses associated with host defence. Transcriptional profiling via RNA-sequencing (RNA-seq) identified numerous fungal genes that were differentially expressed in the kernel environment following the deletion of FUG1, including genes involved in secondary metabolism and mycelial development. Sequence analysis of the Fug1 protein provided evidence for nuclear localization, DNA binding and a domain of unknown function associated with previously characterized transcriptional regulators. This information, combined with the observed transcriptional reprogramming in the deletion mutant, suggests that FUG1 represents a novel class of fungal transcription factors or genes otherwise involved in signal transduction.

Identification and functional analysis of endogenous nitric oxide in a filamentous fungus

In spite of its prevalence in animals and plants, endogenous nitric oxide (NO) has been rarely reported in fungi. We present here our observations on production of intracellular NO and its possible roles during development of Neurospora crassa, a model filamentous fungus. Intracellular NO was detected in hypha 8–16 hours after incubation in Vogel’s minimal liquid media and conidiophores during conidiation using a fluorescent indicator (DAF-FM diacetate). Treatment with cPTIO, an NO scavenger, significantly reduced fluorescence levels and hindered hyphal growth in liquid media and conidiation, whereas exogenous NO enhanced hyphal extension on VM agar media and conidia formation. NO scavenging also dramatically diminished transcription of con-10 and con-13, genes preferentially expressed during conidiation. Our results suggest that intracellular NO is generated in young hypha growing in submerged culture and during conidia development and regulate mycelial development and conidia formation.

Aluminium pre-treatment induces activation of defense responses against Fusarium infection in Triticum aestivum

Pre-treatment with low dose of aluminium sulphate [Al2(SO4)3] was assayed on wheat (Triticum aestivum L.) seedlings for its ability to induce resistance against Fusarium oxysporum infection. Pre-treatment of seven days old germinated wheat seedlings with 50 μM concentration of Al2(SO4)3 reduced the severity of the disease. In Al2(SO4)3 pre-treated seedlings inoculated with fungus reduction in disease severity was correlated with suppression of fungal mycelia development inside the leaf tissues. The activities of peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase were determined as resistance markers. F. oxysporum inoculation induced significant increase of all these enzymes. Such responses were expressed earlier and with much higher magnitude when Al2(SO4)3 pre-treated seedlings were challenged with the pathogen. Slower disease development in Al2(SO4)3 pre-treated seedlings might be due to increased deposition of total phenolic compounds and enhanced level of salicylic acid which restricts pathogen entry.

Biology, cultivation, and medicinal functions of the mushroom Hericium erinaceum

<em>Hericium erinaceum</em> (Bull.: Fr.) Pers. is an edible fungus of great significance in medicine. It is rarely found in Europe, in contrast, it is common in Japan and North America. Its fruitbodies have been well-known for hundreds of years in traditional Chinese medicine and cuisine. A cradle of <em>H. erinaceum</em> cultivation is Asia. In Eastern Europe is rare in natural habitats, but can be successfully cultivated. Both fruitbodies and mycelia are rich in active, health promoting substances. Tests of substances extracted from this mushroom carried out on animals and in vitro have given good results. They can be used in the treatment of cancer, hepatic disorders, Alzheimer’s and Parkinson’s diseases, wound healing. They improve cognitive abilities, support the nervous and immune systems. Promising results have been reported in clinical trials and case reports about the human treatment (e.g., recovery from schizophrenia, an improvement of the quality of sleep, alleviation of the menopause symptoms). The subject of this paper is to summarize information about the development of mycelium, the best conditions for cultivation of fruitbodies, bioactive substances and their use in medicine.

Propolis: An Enrichment Material for Mycelium Development of Oyster Mushroom (<i>Pleurotus ostreatus</i>)

The effect of propolis, taken from honeybee hives in Tokat (Turkey), on mycelium development of oyster mushroom (Pleurotus ostreatus) was investigated. Propolis contains various chemical com- pounds and has antiviral, antibacterial and antifungal activities. Mushroom spores were inoculated in Potato Dextrose Agar (PDA) media containing different proportions of propolis. Mycelium development on media containing 0.10%, 0.30%, and 0.50% propolis occured at the first, third, and fifth days, respectively. The fastest and most intense development was seen on medium containing 0.10% propolis. According to our results, propolis can be used as an enriching material in mushroom cultivating.

Downregulation of Ethylene Production Increases Mycelial Growth and Primordia Formation in the Button Culinary-Medicinal Mushroom, Agaricus bisporus (Agaricomycetes).

Ethylene biosynthesis and function in Agaricus bisporus (the button mushroom) remain uncertain. The enzyme activities of 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) and ACC oxidase (ACO) were detectable in A. bisporus AS2796 and inhibited by α-aminooxyacetic acid and Co2+. We cloned and sequenced 2 ACS genes (Ab-ACS1 and Ab-ACS2) and 1 ACO gene (Ab-ACO) from the mushroom strain. Ab-ACS1 and Ab-ACS2 demonstrated low amino acid sequence similarity. Ab-ACO demonstrated an amino acid sequence completely identical to that of ACO1_AGABI from A. bisporus. Antisense ACO significantly reduced ACO gene expression level, ACO enzyme activity, and ethylene production in the mushroom transformants. The transformants grew faster than the wild-type strain in sterilized compost and normally formed primordia when cultivated in sterilized compost with the sterilized casing vermiculite, but the wild-type strain did not. Our results show that ethylene is synthesized in button mushrooms via the ACC pathway. Ethylene inhibited button mushroom mycelial growth and development.

The effect of oxidative burst suppression or induction on the interaction between brown rust fungus and timopheevi wheat

The role of reactive oxygen species in the interaction between brown rust-causing pathogen Puccinia triticina Erikss. and the disease-resistant species Triticum timopheevii Zhuk. was investigated using salicylic acid treatment to amplify the oxidative burst or treatment with verapamil, an inhibitor of Ca2+-channels to suppress oxidative the burst. The levels of reactive oxygen species in control T. timopheevii plants increased during the early stages of pathogenesis due to O22← generation by stomatal guard cells contacting the appressoria and by mesophyll cells that developed a hypersensitivity reaction in response to the invasion of haustoria. Hydrogen peroxide was subsequently accumulated in the cytoplasm of cells destroyed by hypersensitivity reaction, as well as on the walls of cells contacted with fungal hyphae. The production of O22←, which results in the death of most of the inoculum on the stomata and rapid accumulation of hydrogen peroxide, were enhanced by salicylic acid pretreatment. Pretreatment of the plants with verapamil inhibited the production of reactive oxygen species and hypersensitivity reaction in disease-resistant T. timopheevii plants and thus facilitated the penetration of the fungus into the stomata and more intensive development of mycelium in plant tissues in the early stages of pathogenesis. Some colonies with single haustoria died regardless of production of reactive oxygen species by the plants.

Activity of the novel fungicide oxathiapiprolin against plant-pathogenic oomycetes.

Oxathiapiprolin was the first of the piperidinyl thiazole isoxazoline class of fungicides to be discovered and developed by DuPont in 2007. Although oxathiapiprolin has been reported to have high activity against plant-pathogenic oomycetes, such as Peronospora belbahrii, Phytophthora nicotianae and Ph. capsici, little is known about its effectiveness against other plant-pathogenic oomycetes and its protective and curative properties. Oxathiapiprolin exhibited substantial inhibitory activity against all of the plant-pathogenic oomycetes tested, with EC90 values ranging from 0.14 to 3.36 × 10(-3) µg mL(-1) , except the Pythium species Py. aphanidermatum and Py. deliense. Furthermore, doses as low as 10 µg mL(-1) were found to inhibit zoospore release and motility in Ph. capsici, while the mycelial development and sporangial production of Pseudoperonospora cubensis were restrained by an EC50 of 3.10 × 10(-4) and 5.17 × 10(-4) µg mL(-1) respectively. It was also found that oxathiapiprolin exhibited both protective and curative activity against the development of Ph. capsici infection in pepper plants under greenhouse conditions and in field tests. The present study demonstrated that the novel fungicide oxathiapiprolin exhibits strong inhibitory activity against a range of agriculturally important plant-pathogenic oomycetes, including Phytophthora spp., Peronophythora litchii, Plasmopara viticola, Pe. parasitica, Ps. cubensis and Py. ultimum. © 2015 Society of Chemical Industry.

Mycelial development preceding basidioma formation in Moniliophthora perniciosa is associated to chitin, sugar and nutrient metabolism alterations involving autophagy

We identified and characterized two chitinases, named MpCHIT1 and MpCHIT2, from the fungus Moniliophthora perniciosa – the etiologic agent of witches’ broom disease in cacao tree (Theobroma cacao L.) – during its development, mainly in the mycelia phases preceding the basidioma formation. The expression of MpCHIT1 and MpCHIT2, together with MpCHS and MpATG8 (chitin synthase and autophagy genes, respectively), was analyzed during the M. perniciosa growth and development on bran-based solid medium as well as in liquid medium containing H2O2 or rapamycin (oxidative and nutritional related-autophagy stress agents, respectively). In order to link the expression of chitin metabolism-related genes to nutritional composition influencing fungus development, we also quantified total and reduced sugars, as well as macro- and micronutrients in the bran-based solid medium. The expression analysis showed that the MpCHS expression increased through mycelial development and then decreased in the primordium and basidioma phases, while the expression of MpCHIT1 and MpCHIT2 was higher in basidioma and primordium phases, respectively. Moreover, the expression pattern of MpCHIT1 and MpCHIT2 is distinct, the second correlated with the MpATG8 expression pattern and possibly with autophagy process, while the first may be related to the basidioma formation. The quantification of total and reduced sugars, as well as macro- and micronutrients supported the idea that the cell wall restructuration due to MpCHS, MpCHIT1 and MpCHIT2 is related to stress and fungal nutrient reallocation, allowing the formation and development of the basidioma. Experiments involving M. perniciosa growth on liquid medium containing H2O2 or rapamycin showed that MpCHIT1 and MpCHIT2 were over-expressed in response to oxidative but also to nutritional related-autophagy stresses. Interestingly, the expression level of MpCHS, MpCHIT1 and MpCHIT2 in presence of rapamycin is similar to the one observed in the primordium and basidioma from bran-based solid medium. The analysis of the overall data allowed designing a general scheme of chitin metabolism and autophagy during M. perniciosa development, focusing on the mycelium phases as crucial and environmentally influenced steps preceding the primordium and basidioma formation. These data support the idea that the nutritional environment of M. perniciosa influences its development and life cycle.

Screening and characterization of endophytic Bacillus and Paenibacillus strains from medicinal plant Lonicera japonica for use as potential plant growth promoters.

A total of 48 endophytic bacteria were isolated from surface-sterilized tissues of the medicinal plant Lonicera japonica, which is grown in eastern China; six strains were selected for further study based on their potential ability to promote plant growth in vitro (siderophore and indoleacetic acid production). The bacteria were characterized by phylogenetically analyzing their 16S rRNA gene similarity, by examining their effect on the mycelial development of pathogenic fungi, by testing their potential plant growth-promoting characteristics, and by measuring wheat growth parameters after inoculation. Results showed that the number of endophytic bacteria in L. japonica varied among different tissues, but it remained relatively stable in the same tissues from four different plantation locations. Among the three endophytic strains, strains 122 and 124 both had high siderophore production, with the latter showing the highest phosphate solubilization activity (45.6 mg/L) and aminocyclopropane-1-carboxylic acid deaminase activity (47.3 nmol/mg/h). Strain 170 had the highest indoleacetic acid (IAA) production (49.2 mg/L) and cellulase and pectinase activities. After inoculation, most of the six selected isolates showed a strong capacity to promote wheat growth. Compared with the controls, the increase in the shoot length, root length, fresh weight, dry weight, and chlorophyll content was most remarkable in wheat seedlings inoculated with strain 130. The positive correlation between enzyme (cellulose and pectinase) activity and inhibition rate on Fusarium oxysporum, the IAA production, and the root length of wheat seedlings inoculated with each tested endophytic strain was significant in regression analysis. Deformity of pathogenic fungal mycelia was observed under a microscope after the interaction with the endophytic isolates. Such deformity may be directly related to the production of hydrolytic bacterial enzymes (cellulose and pectinase). The six endophytic bacterial strains were identified to be Paenibacillus and Bacillus strains based on the results of 16S rRNA gene sequencing analysis and their physiological and biochemical characteristics. Results indicate the promising application of endophytic bacteria to the biological control of pathogenic fungi and the improvement of wheat crop growth.

The Shewanella algae strain YM8 produces volatiles with strong inhibition activity against Aspergillus pathogens and aflatoxins

Aflatoxigenic Aspergillus fungi and associated aflatoxins are ubiquitous in the production and storage of food/feed commodities. Controlling these microbes is a challenge. In this study, the Shewanella algae strain YM8 was found to produce volatiles that have strong antifungal activity against Aspergillus pathogens. Gas chromatography-mass spectrometry profiling revealed 15 volatile organic compounds (VOCs) emitted from YM8, of which dimethyl trisulfide was the most abundant. We obtained authentic reference standards for six of the VOCs; these all significantly reduced mycelial growth and conidial germination in Aspergillus; dimethyl trisulfide and 2,4-bis(1,1-dimethylethyl)-phenol showed the strongest inhibitory activity. YM8 completely inhibited Aspergillus growth and aflatoxin biosynthesis in maize and peanut samples stored at different water activity levels, and scanning electron microscopy revealed severely damaged conidia and a complete lack of mycelium development and conidiogenesis. YM8 also completely inhibited the growth of eight other agronomically important species of phytopathogenic fungi: A. parasiticus, A. niger, Alternaria alternate, Botrytis cinerea, Fusarium graminearum, Fusarium oxysporum, Monilinia fructicola, and Sclerotinia sclerotiorum. This study demonstrates the susceptibility of Aspergillus and other fungi to VOCs from marine bacteria and indicates a new strategy for effectively controlling these pathogens and the associated mycotoxin production during storage and possibly in the field.

First report of Sclerotinia rot of pigeonpea caused by Sclerotinia sclerotiorum (Lib.) de Bary in India

Sclerotinia stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary was observed for the first time on pigeonpea in Pusa, Bihar (India) during the years 2012–2014. Typical symptoms of the disease included blighting of twigs, stem lesions, and development of cottony white mycelium and numerous large sclerotia on diseased plant parts. The fungus was identified on the basis of cultural and morphological characteristics, and its pathogenicity was also established. The internal transcribed spacer (ITS) region of pathogen was amplified with primers ITS1 and ITS4, which revealed 100% query coverage along with 99% identity with S. sclerotiorum recovered from different hosts. The highest disease incidence was recorded on cultivar ‘ICPL151’, whereas cultivars ‘MAL13’ and ‘Kudrat’ were observed to have significantly less disease under natural conditions.

Effect of culture conditions on radial growth, submerged biomass and moisture content of Lentinus tuberregium, a new edible mushroom

The growth performance of mushroom culture Lentinus tuberregium was studied using both cultural and environmental factors. Development of cellular biomass was analysed in 10 different media along with effect of inoculum size, incubation period, pH and temperature. Different media showed different growth characteristics with more or less impact to the mycelium development. Among the 10 different media used, Yeast malt extract medium (YME) was found to be the best medium, however malt extract broth, glucose yeast extract peptone and potato dextrose broth media was also found to be good towards cellular biomass production. No supportive effect of inoculum size was observed on cellular growth development. Among various pH and temperature range, 6.0 and 25 oC impact best condition for the growth of mushroom culture.

Deep sequencing analysis of transcriptomes in Aspergillus flavus in response to resveratrol.

BackgroundResveratrol has been reported as a natural phytoalexin that inhibits infection or the growth of certain fungi including Aspergillus flavus. Our previous research revealed that aflatoxin production in A. flavus was reduced in medium with resveratrol. To understand the molecular mechanism of the A. flavus response to resveratrol treatment, the high-throughput paired-end RNA-Seq was applied to analyze the transcriptomic profiles of A. flavus.ResultsIn total, 366 and 87 genes of A. flavus were significantly up- and down- regulated, respectively, when the fungus was treated with resveratrol. Gene Ontology (GO) functional enrichment analysis revealed that 48 significantly differentially expressed genes were involved in 6 different terms. Most genes in the aflatoxin biosynthetic pathway genes cluster (#54) did not show a significant change when A. flavus was treated with resveratrol, but 23 of the 30 genes in the #54 cluster were down-regulated. The transcription of aflA and aflB was significantly suppressed under resveratrol treatment, resulting in an insufficient amount of the starter unit hexanoate for aflatoxin biosynthesis. In addition, resveratrol significantly increased the activity of antioxidative enzymes that destroy radicals, leading to decreased aflatoxin production. Moreover, stuA, fluG, flbC, and others genes involved in mycelial and conidial development were down-regulated, which disrupted the cell’s orderly differentiation and blocked conidia formation and mycelia development. The transcripts of laeA and veA were slightly inhibited by resveratrol, which may partly decrease aflatoxin production and depress conidia formation.ConclusionsResveratrol can affect the expression of A. flavus genes that are related to developmental and secondary metabolic processes, resulting in decreased aflatoxin production and conidia formation and could also cause abnormal mycelia development. These results provide insight into the transcriptome of A. flavus in response to resveratrol and a new clew for further study in regulation of aflatoxin biosynthesis in A. flavus.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0513-6) contains supplementary material, which is available to authorized users.

Efficacy of water- and oil-in-water-formulated Metarhizium anisopliae in Rhipicephalus sanguineus eggs and eclosing larvae.

Conidia of the entomopathogenic fungus Metarhizium anisopliae (Ascomycota: Clavicipitaceae) were assessed against Rhipicephalus sanguineus (Arachnida: Ixodidae) eggs under laboratory conditions. Clusters of 25 eggs were applied either directly with the fungal conidial formulations or set on previously fungus-treated filter paper. Treatments consisted of conidia formulated in water or an oil-in-water emulsion at final concentrations of 3.3 × 10(3), 10(4), 3.3 × 10(4), 10(5), or 3.3 × 10(5) conidia/cm(2). The development of mycelium and new conidia on egg clusters incubated at 25 °C and humidity close to saturation depended on conidial concentration, formulation, and application technique. No larvae eclosed from eggs after direct applications of conidia regardless of the formulation. The eclosion and survival of larvae from indirectly treated egg clusters depended on the type of formulation and conidial concentration applied. Oil-in-water formulations of conidia demonstrated the highest activity against eggs of R. sanguineus.