RESUMEN
White-nose syndrome is a fungal disease responsible for the rapid decline of North American bat populations. This study addressed a novel method for inactivating Pseudogymnoascus destructans, the causative agent of WNS, using ultraviolet A (UVA) or B (UVB) radiation in combination with methoxsalen, a photosensitizer from the furanocoumarin family of compounds. Fungal spore suspensions were diluted in micromolar concentrations of methoxsalen (50-500 µM), then exposed to fixed doses of UVA radiation (500-5000 mJ/cm2), followed by plating on germination media. These plates were examined for two to four weeks for evidence of spore germination or inactivation, along with resultant growth or inhibition of P. destructans colonies. Pretreatment of fungal spores with low doses of methoxsalen resulted in a UVA dose-dependent inactivation of the P. destructans spores. All doses of methoxsalen paired with 500 mJ/cm2 of UVA led to an approximate two-log10 (~99%) reduction in spore viability, and when paired with 1000 mJ/cm2, a four-log10 or greater (>99.99%) reduction in spore viability was observed. Additionally, actively growing P. destructans colonies treated directly with methoxsalen and either UVA or UVB radiation demonstrated UV dose-dependent inhibition and termination of colony growth. This novel approach of using a photosensitizer in combination with UV radiation to control fungal growth may have broad, practical application in the future.
Asunto(s)
Ascomicetos/efectos de la radiación , Quirópteros/microbiología , Metoxaleno/administración & dosificación , Micosis/veterinaria , Fármacos Fotosensibilizantes/administración & dosificación , Terapia Ultravioleta , Animales , Ascomicetos/crecimiento & desarrollo , Ascomicetos/patogenicidad , Micosis/radioterapia , Esporas Fúngicas/patogenicidad , Esporas Fúngicas/efectos de la radiación , SíndromeRESUMEN
The effects of gamma irradiation (0.5, 1.0, 1.5 and 2.5 kGy doses) on Tuber aestivum packaged under modified atmosphere was evaluated. The respiration rate, microbial populations, sensory characteristics and content of bioactive compounds (total carbohydrates, chitins, ß-glucans, proteins, total phenols and sterols) were monitored from immediately after treatment up to day 42 of storage at 4 °C. All the irradiation treatments tested reduced the microbial groups studied by more than 3 log cfu/g. Increasing irradiation doses slowed down the subsequent microbial development throughout the conservation period for all the groups studied. The irradiation treatments did not negatively affect truffle sensory characteristics. Only a slight visible superficial yeast growth was detected at the end of the shelf-life in all doses applied. Total carbohydrate content, chitins, ß-glucans and proteins levels were not affected after irradiation. However, sterols, particularly stigmasterol, slightly decreased after irradiation, while levels of phenolic compounds doubled during storage. Gamma irradiation (2.5 kGy) could be used to extend the shelf-life of summer truffles packaged under modified atmosphere, since no remarkable reduction of bioactive compounds were noticed after 42 days of storage, and their sensory and microbial parameters were of higher quality than those of non-irradiated controls.
Asunto(s)
Ascomicetos/efectos de la radiación , Irradiación de Alimentos/métodos , Embalaje de Alimentos/métodos , Almacenamiento de Alimentos , Fitoquímicos/efectos de la radiación , Ascomicetos/química , Recuento de Colonia Microbiana , Microbiología de Alimentos , Calidad de los Alimentos , Rayos gamma , Fitoquímicos/análisisRESUMEN
Taxol, a phyto-extracted diterpenoid, is the most commercially needed drug in cancer chemotherapy. In spite of the microbial production of taxol being successful and prospective, the reported yields are still not sufficient for large-scale production. Thus, the discovery of new taxol-producing microbial strains and production enhancement methodologies such as process optimization, strain improvement, and immobilization technique are the main objectives. In this paper, a taxol-producing start strain Epicoccum nigrum TXB502 (initial yield 61.35 µg L-1) was isolated from Taxus baccata and identified by morphological and molecular tools. The optimum cultivation and nutritional conditions were assessed by testing one parameter at a time approach that resulted in 88.59% significant production increase. In addition, a stable mutant with improved productivity (40.07% yield increase in comparison with the parent strain) was successfully developed after gamma irradiation mutagenesis of the start strain. The taxol titer was further improved via testing different immobilization carriers for both spores and mycelia of this mutant. Over taxol production was achieved using alginate-immobilized mycelia with the feasibility of conducting six successive production cycles in a semi-continuous form. The final total concentration reached 8187.77 µg taxol 6 L-1 which represents approximately 22-fold increase, as compared to the initial titer of the start strain. These findings can pave the way for the prospective industrial manufacturing of taxol, as the achieved taxol production in this study is the highest reported by academic laboratories for microbial cultures. KEY POINTS: ⢠Discovery of a new taxol-producing endophytic fungus E. nigrum TXB502 strain. ⢠Taxol yield was successfully improved via bioprocess optimization and strain mutagenesis. ⢠Alginate-immobilized mycelia were efficient for a semi-continuous production of taxol. ⢠The final total concentration of taxol showed approximately 22-fold increase as compared to the initial titer.
Asunto(s)
Antineoplásicos/metabolismo , Ascomicetos/genética , Ascomicetos/metabolismo , Rayos gamma , Mutagénesis , Paclitaxel/biosíntesis , Ascomicetos/efectos de la radiación , Medios de Cultivo/química , Fermentación , Microbiología Industrial/métodos , Micelio/metabolismo , Taxus/microbiologíaRESUMEN
Powdery mildews are obligate biotrophic fungal pathogens causing important diseases of plants worldwide. Very little is known about the requirements for their pathogenicity at the molecular level. This is largely due to the inability to culture these organisms in vitro or to modify them genetically. Here, we describe a mutagenesis procedure based on ultraviolet (UV) irradiation to accumulate mutations in the haploid genome of the barley powdery mildew pathogen Blumeria graminis f. sp. hordei. Exposure of B. graminis f. sp. hordei conidia to different durations of UV-C radiation (10 s to 12 min) resulted in a reduced number of macroscopically visible fungal colonies. B. graminis f. sp. hordei colony number was negatively correlated with exposure time and the total number of consecutive cycles of UV irradiation. Dark incubation following UV exposure further reduced fungal viability, implying that photoreactivation is an important component of DNA repair in B. graminis f. sp. hordei. After several rounds of UV mutagenesis, we selected two mutant isolates in addition to the parental B. graminis f. sp. hordei K1 isolate for whole-genome resequencing. By combining automated prediction of sequence variants and their manual validation, we identified unique UV-induced mutations in the genomes of the two isolates. Most of these mutations were in the up- or downstream regions of genes or in the intergenic space. Some of the variants detected in genes led to predicted missense mutations. As an additional insight, our bioinformatic analyses revealed a complex population structure within supposedly clonal B. graminis f. sp. hordei isolates.
Asunto(s)
Ascomicetos , Genoma Fúngico/efectos de la radiación , Mutagénesis , Enfermedades de las Plantas/microbiología , Ascomicetos/genética , Ascomicetos/patogenicidad , Ascomicetos/efectos de la radiación , Secuenciación de Nucleótidos de Alto Rendimiento , Hordeum/microbiología , Análisis de Secuencia de ADN , Rayos UltravioletaRESUMEN
Fungi that share light-flooded habitats with phototrophs may profit from their excess photosynthetic products. But to cope with sunlight-associated stresses [e.g. high temperatures, UV radiation with associated DNA damage, accumulation of reactive oxygen species (ROS), desiccation and osmotic stresses] it is important for fungi to accurately sense and respond to changes in light. To test the hypothesis that light is an environmental cue that Ascomycota use to coordinate growth, stress responses as well as to establish pathogenic or symbiotic relationships, the photoreceptor (PR) distribution in species from different ecological niches was analysed. The genomes of black [dihydroxynaphthalene (DHN) melanin-containing] fungi from phyllosphere and exposed solid surfaces contain multiple photoreceptors (PRs). The plant pathogen Botrytis cinerea (Leotiomycetes) has a highly sophisticated photosensory and signalling system that helps to avoid light and to locate susceptible hosts. Rock-inhabiting Dothideomycetes and Eurotiomycetes including Knufia petricola possess equal numbers of PRs along with the same set of protective pigments. This similarity between black fungi from plant and rock surfaces suggests that photoperception and -regulation are important for fungi that receive nutrients through cooperation with phototrophs. Genetic tools for manipulating K. petricola exist and will be used to test this idea.
Asunto(s)
Ascomicetos , Luz , Ascomicetos/genética , Ascomicetos/efectos de la radiación , PigmentaciónRESUMEN
Filamentous fungi are known producers of important secondary metabolites. In spite of this, the majority of these organisms have not been studied at the genome level, leaving many of the bioactive molecules they produce undiscovered. In this study, we explore the secondary metabolite potential of an understudied fungus, Hyphodiscus hymeniophilus. By sequencing and assembling the first genome from this genus, we show that this fungus has genes for at least 20 natural products and that many of these products are likely novel. One of these metabolites is identified: a new, red-pigmented member of the azaphilone class, hyphodiscorubrin. We show that this metabolite is only produced when the fungus is grown in the light. Furthermore, the biosynthetic gene cluster of hyphodiscorubrin is identified though homology to other known azaphilone producing clusters.
Asunto(s)
Oxidorreductasas de Alcohol/genética , Ascomicetos/genética , Ascomicetos/metabolismo , Proteínas Bacterianas/genética , Genoma Fúngico/genética , Luz , Familia de Multigenes/genética , Análisis de Secuencia de ADN , Ascomicetos/enzimología , Ascomicetos/efectos de la radiación , FenofibratoRESUMEN
AIMS: Different endophytic fungi were isolated and screened for their digoxin-producing ability. Strain improvement and different culture conditions were studied for more effective production of digoxin. METHODS AND RESULTS: Among the isolated fungi, an isolate produced digoxin in a concentration of 2·07 mg l-1 . The digoxin-producing fungal isolate was identified as Epicoccum nigrum Link according to the morphological features and phylogenetic analyses. The potentiality of the fungal strain for production enhancement of digoxin was performed by gamma radiation mutagenesis. Gamma irradiation dose of 1000 Gy intensified the digoxin yield by five-fold. Using this dose, a stable mutant strain with improved digoxin productivity was isolated and the stability for digoxin production was followed up across four successive generations. In the effort to increase digoxin magnitude, selection of the proper cultivation medium, addition of some elicitors to the most proper medium and several physical fermentation conditions were tested. Fermentation process carried out in malt extract autolysate medium (pH 6·5) supplemented by methyl jasmonate and inoculated with 2 ml of 6-day-old culture and incubated at 25°C for 10 days stimulated the highest production of digoxin to attain 50·14 mg l-1 . Moreover, cytotoxicity of digoxin separated from the fungal culture was tested against five different cancer cell lines. Based on the MTT assay, digoxin inhibited the proliferation of the five different cancer cell lines and the recorded 50% inhibitory concentration ranged from 10·76 to 35·14 µg ml-1 . CONCLUSIONS: This is the first report on the production and enhancement of digoxin using fungal fermentation as a new and alternate source with high productivity. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings offer new and alternate sources with excellent biotechnological potential for digoxin production by fungal fermentation. Moreover, digoxin proved to be a promising anticancer agent whose anticancer potential should be assessed in prospective cancer therapy.
Asunto(s)
Antineoplásicos/metabolismo , Ascomicetos/genética , Ascomicetos/metabolismo , Digoxina/metabolismo , Animales , Antineoplásicos/farmacología , Ascomicetos/aislamiento & purificación , Ascomicetos/efectos de la radiación , Células CHO , Línea Celular Tumoral , Cricetulus , Digoxina/farmacología , Endófitos/genética , Endófitos/aislamiento & purificación , Endófitos/metabolismo , Endófitos/efectos de la radiación , Fermentación , Rayos gamma , Humanos , Mutagénesis , FilogeniaRESUMEN
BACKGROUND: Chromoblastomycosis is a chronic skin and subcutaneous fungal infection caused by dematiaceous fungi and is associated with low cure and high relapse rates. In southern China, Fonsecaea monophora and Fonsecaea pedrosoi are the main causative agents. PRINCIPAL FINDINGS: We treated 5 refractory and complex cases of chromoblastomycosis with 5-aminolevulinic acid photodynamic therapy (ALA-PDT) combined with oral antifungal drugs. The lesions improved after 4 to 9 sessions of ALA-PDT treatment at an interval of one or two weeks, and in some cases, mycological testing results became negative. The isolates were assayed for susceptibility to antifungal drugs and ALA-PDT in vitro, revealing sensitivity to terbinafine, itraconazole and voriconazole, with ALA-PDT altering the cell wall and increasing reactive oxygen species production. CONCLUSIONS: These results provide the basis for the development of a new therapeutic approach, and ALA-PDT combined with oral antifungal drugs constitutes a promising alternative method for the treatment of refractory and complex cases of chromoblastomycosis.
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Ácido Aminolevulínico/uso terapéutico , Antifúngicos/uso terapéutico , Ascomicetos/efectos de los fármacos , Ascomicetos/efectos de la radiación , Cromoblastomicosis/tratamiento farmacológico , Cromoblastomicosis/radioterapia , Fotoquimioterapia/métodos , China , Cromoblastomicosis/patología , ADN de Hongos , Femenino , Humanos , Itraconazol/uso terapéutico , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Piel/metabolismo , Terbinafina/uso terapéutico , Voriconazol/uso terapéuticoRESUMEN
Lophodermium piceae represents the most common Norway spruce needle endophyte. The aim of this study was to find out whether subpopulations of L. piceae in climatically different environments (in which Norway spruce occurs natively) are adapted to local thermal conditions. L. piceae's ability for thermal adaptation was investigated by determining growth rates of 163 isolates in vitro at four different temperatures: 2, 6, 20 and 25 °C. Isolates were obtained between 1995 and 2010 from apparently healthy needles sampled in Finland, Poland, Switzerland, Italy and southeastern Siberia. The sampling sites represent seven climatically distinct locations. Results were evaluated in relation to the age and geographic origin of the isolate, in addition to the highest and lowest average monthly temperature of the sampling location. We found a significant correlation between the growth rate and the age of the isolate at 25 °C. Variation in growth rates between subpopulations was low compared to within subpopulations. Only at 2 °C did statistically significant differences between the average growth rates of subpopulations emerge. These results suggest that L. piceae covers the whole distribution area of Norway spruce but that generally the thermal reaction norm of its subpopulations has not changed according to local temperature ranges, despite high contrast in thermal conditions across this vast area. Therefore, it would appear that the thermal environment is not a crucial factor in assessing the fitness of this fungal species within the native range of Norway spruce.
Asunto(s)
Adaptación Biológica , Ascomicetos/crecimiento & desarrollo , Ascomicetos/efectos de la radiación , Endófitos/crecimiento & desarrollo , Endófitos/efectos de la radiación , Picea/microbiología , Temperatura , Adaptación Fisiológica , Ascomicetos/aislamiento & purificación , Europa (Continente) , Hojas de la Planta/microbiología , SiberiaRESUMEN
Despite the recent advancements in culturomics, isolation of the majority of environmental microbiota performing critical ecosystem services, such as bioremediation of contaminants, remains elusive. Towards this end, we conducted a metagenomics-guided comparative assessment of soil microbial diversity and functions present in uraniferous soils relative to those that grew in diffusion chambers (DC) or microbial traps (MT), followed by isolation of uranium (U) resistant microbiota. Shotgun metagenomic analysis performed on the soils used to establish the DC/MT chambers revealed Proteobacterial phyla and Burkholderia genus to be the most abundant among bacteria. The chamber-associated growth conditions further increased their abundances relative to the soils. Ascomycota was the most abundant fungal phylum in the chambers relative to the soils, with Penicillium as the most dominant genus. Metagenomics-based taxonomic findings completely mirrored the taxonomic composition of the retrieved isolates such that the U-resistant bacteria and fungi mainly belonged to Burkholderia and Penicillium species, thus confirming that the chambers facilitated proliferation and subsequent isolation of specific microbiota with environmentally relevant functions. Furthermore, shotgun metagenomic analysis also revealed that the gene classes for carbohydrate metabolism, virulence, and respiration predominated with functions related to stress response, membrane transport, and metabolism of aromatic compounds were also identified, albeit at lower levels. Of major note was the successful isolation of a potentially novel Penicillium species using the MT approach, as evidenced by whole genome sequence analysis and comparative genomic analysis, thus enhancing our overall understanding on the uranium cycling microbiota within the tested uraniferous soils.
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Microbiota/genética , Microbiología del Suelo , Uranio/toxicidad , Ascomicetos/genética , Ascomicetos/efectos de la radiación , Biodegradación Ambiental , Burkholderia/genética , Burkholderia/efectos de la radiación , Ecosistema , Pradera , Humanos , Metagenómica , Microbiota/efectos de la radiación , Penicillium/genética , Penicillium/efectos de la radiación , Ríos , Estados UnidosRESUMEN
UV-C irradiation is known to compromise germination of Blumeria graminis conidia and to reduce powdery mildew infestation. However, only scarce information is available on the effects of UV-C irradiation on B. graminis appressorium formation. Applying a Formvar® resin-based in vitro system allowed for analyzing B. graminis germination and appressorium formation in absence of plant defense. UV-C irradiation more strongly affected the differentiation of appressoria than conidial germination. In vivo and in vitro, a single dose of 100 J m-2 UV-C was sufficient to reduce germination to less than 20 % and decrease appressorium formation to values below 5 %. UV-C irradiation negatively affected pustule size and conidiation. White light-mediated photoreactivation was most effective immediately after UV-C irradiation, indicating that a prolonged phase of darkness after UV-C treatment increases the efficacy of B. graminis control. UV-C irradiation increased transcript levels of three putative B. graminis photolyase genes, while mere white light or blue light irradiation did not contribute to the transcriptional up-regulation. Thus, UV-C irradiation effectively controls B. graminis infestation and proliferation by restricting prepenetration processes. Nevertheless, photoreactivation plays an important role in UV-C-based powdery mildew control in crops and hence has to be considered for planning specific irradiation schedules.
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Ascomicetos/crecimiento & desarrollo , Ascomicetos/efectos de la radiación , Desoxirribodipirimidina Fotoliasa/biosíntesis , Esporas Fúngicas/crecimiento & desarrollo , Esporas Fúngicas/efectos de la radiación , Transcripción Genética , Rayos Ultravioleta , Reparación del ADN/efectos de la radiación , Hordeum/microbiología , Luz , Enfermedades de las Plantas/microbiologíaRESUMEN
The BIOMEX (BIOlogy and Mars Experiment) is part of the European Space Agency (ESA) space mission EXPOSE-R2 in Low-Earth Orbit, devoted to exposing microorganisms for 1.5 years to space and simulated Mars conditions on the International Space Station. In preparing this mission, dried colonies of the Antarctic cryptoendolithic black fungus Cryomyces antarcticus CCFEE 515, grown on martian and lunar analog regolith pellets, were subjected to several ground-based preflight tests, Experiment Verification Tests, and Science Verification Tests (SVTs) that were performed to verify (i) the resistance of our model organism to space stressors when grown on extraterrestrial rock analogs and (ii) the possibility of detecting biomolecules as potential biosignatures. Here, the results of the SVTs, the last set of experiments, which were performed in ultraviolet radiation combined with simulated space vacuum or simulated martian conditions, are reported. The results demonstrate that C. antarcticus was able to tolerate the conditions of the SVT experiment, regardless of the substratum in which it was grown. DNA maintained high integrity after treatments and was confirmed as a possible biosignature; melanin, which was chosen to be a target for biosignature detection, was unambiguously detected by Raman spectroscopy.
Asunto(s)
Ascomicetos/fisiología , Medio Ambiente Extraterrestre , Marte , Ascomicetos/efectos de la radiación , Ascomicetos/ultraestructura , Daño del ADN , Melaninas/análisis , Espectrometría Raman , Rayos UltravioletaRESUMEN
Hypocrellin A (HA), a promising photosensitizer for anticancer photodynamic therapy (PDT), is a fungal perylenequinone pigment from the fruiting body of Shiraia bambusicola, a traditional Chinese medicine for treating skin diseases. The mycelial cultures are becoming a biotechnological alternative for HA production. In this study, light of different wavelengths was investigated to develop an effective eliciting strategy for HA production in the cultures. Under red LED light (627 nm) at 200 lux, the maximum HA production (175.53 mg L-1 ) in mycelium cultures was reached after 8 days, about 3.82-fold of the dark control. Red light not only promoted HA biosynthesis in mycelia (intracellular HA), but also stimulated HA secretion into the medium (extracellular HA). We found 14 of 310 transcripts differentially expressed under red light treatment were possible candidate genes for HA biosynthetic pathway. Gene ontology (GO) analysis revealed that red light treatment could change the gene expressions responsible for HA biosynthesis and the transmembrane activity, suggesting both intracellular HA and its secretion could contribute to the enhancement of total HA production in the cultures. The results provided new insights of red light elicitation and effective strategy for HA production in mycelium cultures.
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Ascomicetos/efectos de la radiación , Luz , Perileno/análogos & derivados , Fármacos Fotosensibilizantes/metabolismo , Quinonas/metabolismo , Ascomicetos/genética , Ascomicetos/metabolismo , Vías Biosintéticas , Permeabilidad de la Membrana Celular/efectos de la radiación , Genes Fúngicos , Anotación de Secuencia Molecular , Micelio/crecimiento & desarrollo , Perileno/metabolismo , Fenol , TranscriptomaRESUMEN
The search for life beyond Earth involves investigation into the responses of model organisms to the deleterious effects of space. In the frame of the BIOlogy and Mars Experiment, as part of the European Space Agency (ESA) space mission EXPOSE-R2 in low Earth orbit (LEO), dried colonies of the Antarctic cryptoendolithic black fungus Cryomyces antarcticus CCFEE 515 were grown on martian and lunar analog regolith pellets, and exposed for 16 months to LEO space and simulated Mars-like conditions on the International Space Station. The results demonstrate that C. antarcticus was able to tolerate the combined stress of different extraterrestrial substrates, space, and simulated Mars-like conditions in terms of survival, DNA, and ultrastructural stability. Results offer insights into the habitability of Mars for future exploration missions on Mars. Implications for the detection of biosignatures in extraterrestrial conditions and planetary protection are discussed.
Asunto(s)
Ascomicetos/fisiología , Exobiología , Marte , Ascomicetos/efectos de la radiación , Ascomicetos/ultraestructura , Daño del ADN , Medio Ambiente Extraterrestre , Luna , Rayos UltravioletaRESUMEN
Ultraviolet-C (UV-C) radiation has been reported to induce defence responses to pathogens in growing crops and described as a new environmentally friendly method for disease control. However, whether the effect of the induced defence mechanisms will persist after the stress imposed by UV-C is alleviated and how these mechanisms interact with pathogen elicitors upon infection have not yet been investigated. Thus, we inoculated strawberry plants with Mycosphaerella fragariae, the causal agent of leaf spot disease, after 5 weeks of repeated UV-C irradiation treatment (cumulative dose of 10.2 kJ m-2 ) and investigated the alteration of gene expression and biochemical phenotypes. The results revealed that UV-C treatment had a significant impact on gene expression in strawberry leaves and led to the overexpression of a set of genes involved in plant-pathogen interaction. UV-C-treated leaves displayed a stronger response to infection after inoculation, with reduced symptoms and increases in accumulation of total phenolics and volatile terpenes, higher expression of pathogenesis-related proteins and the activity of several defence enzymes. This study presumptively describe, for the first time, the involvement of terpenes, reactive oxygen species, and abscisic acid, salicylic acid, jasmonic acid, and their transduction factors, in the network underpinning UV-C priming of growing crops for improved protection against pathogens.
Asunto(s)
Ascomicetos , Fragaria/efectos de la radiación , Enfermedades de las Plantas/microbiología , Reguladores del Crecimiento de las Plantas/metabolismo , Hojas de la Planta/efectos de la radiación , Especies Reactivas de Oxígeno/metabolismo , Terpenos/metabolismo , Rayos Ultravioleta , Ascomicetos/crecimiento & desarrollo , Ascomicetos/efectos de la radiación , Fragaria/metabolismo , Fragaria/microbiología , Regulación de la Expresión Génica de las Plantas/efectos de la radiación , Hojas de la Planta/metabolismo , Hojas de la Planta/microbiologíaRESUMEN
Despite living organisms are not exposed to acute ionizing radiation under natural conditions, some exhibit a high radiation resistance. Understanding this phenomenon is important for assessing the impact of radiation-related accidents, occupational exposures and space missions. In this context, in this study we analyzed the effect of gamma rays on the Antarctic cryptoendolithic melanized fungus Friedmanniomyces endolithicus CCFEE 5208 and demonstrated its resistance to acute doses of gamma radiation (up to 400 Gy), accompanied by increase in metabolic activity.
Asunto(s)
Ascomicetos/fisiología , Ascomicetos/efectos de la radiación , Rayos gamma , Viabilidad Microbiana/efectos de la radiación , Regiones Antárticas , Ascomicetos/aislamiento & purificación , Metabolismo/efectos de los fármacos , Oxidación-Reducción , Pigmentos Biológicos/metabolismoRESUMEN
The Antarctic black meristematic fungus Cryomyces antarcticus CCFEE 515 occurs endolithically in the McMurdo Dry Valleys of Antarctica, one of the best analogue for Mars environment on Earth. To date, this fungus is considered one of the best eukaryotic models for astrobiological studies and has been repeatedly selected for space experiments in the last decade. The obtained results are reviewed here, with special focus on responses to space relevant irradiation, UV radiation, and both sparsely and densely ionizing radiation, which represent the major injuries for a putative space-traveller. The remarkable resistance of this model organism to space stress, its radioresistance in particular, and mechanisms involved, significantly contributed to expanding our concept of limits for life and provided new insights on the origin and evolution of life in planetary systems, habitability, and biosignatures for life detection as well as on human protection during space missions.
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Ascomicetos/crecimiento & desarrollo , Ascomicetos/efectos de la radiación , Tolerancia a Radiación , Regiones Antárticas , Exobiología , Melaninas/fisiología , Viabilidad Microbiana/efectos de la radiación , Radiación Ionizante , Vuelo Espacial , Rayos UltravioletaRESUMEN
Pseudogymnoascus destructans is the causal agent of bat white-nose syndrome (WNS), which is devastating some North American bat populations. Previous transcriptome studies provided insight regarding the molecular mechanisms involved in WNS; however, it is unclear how different environmental parameters could influence pathogenicity. This information could be useful in developing management strategies to mitigate the negative impacts of P. destructans on bats. We cultured three P. destructans isolates from Atlantic Canada on two growth media (potato dextrose agar and Sabouraud dextrose agar) that differ in their nitrogen source, and at two separate incubation temperatures (4 C and 15 C) that approximate the temperature range of bat hibernacula during the winter and a temperature within its optimal mycelial growth range. We conducted RNA sequencing to determine transcript levels in each sample and performed differential gene expression (DGE) analyses to test the influence of growth medium and incubation temperature on gene expression. We also compared our in vitro results with previous RNA-sequencing data sets generated from P. destructans growing on the wings of a susceptible host, Myotis lucifugus. Our findings point to a critical role for substrate and incubation temperature in influencing the P. destructans transcriptome. DGE analyses suggested that growth medium plays a larger role than temperature in determining P. destructans gene expression and that although the psychrophilic fungus responds to different nitrogen sources, it may have evolved for continued growth at a broad range of low temperatures. Further, our data suggest that down-regulation of the RNA-interference pathway and increased fatty acid metabolism are involved in the P. destructans-bat interaction. Finally, we speculate that to reduce the activation of host defense responses, P. destructans minimizes changes in the expression of genes encoding secreted proteins during bat colonization.
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Ascomicetos/crecimiento & desarrollo , Ascomicetos/efectos de la radiación , Medios de Cultivo/química , Perfilación de la Expresión Génica , Temperatura , Animales , Ascomicetos/aislamiento & purificación , Canadá , Quirópteros/microbiologíaRESUMEN
Hypocrellin A (HA) is a major bioactive perylenequinone from the fruiting body of Shiraia bambusicola used for the treatment of skin diseases and developed as a photodynamic therapy (PDT) agent against cancers and viruses. The mycelial culture of S. bambusicola under dark is a biotechnological alternative for HA production but with low yield. In this study, light and dark conditions were investigated to develop effective elicitation on HA production in the cultures. Our results showed the constant light at 200â¯lx stimulated HA production without any growth retardation of mycelia. A light/dark shift (24: 24â¯h) not only increased HA content in mycelia by 65%, but stimulated HA release into the medium with the highest total HA production 181.67â¯mg/L on day 8, about 73% increase over the dark control. Moreover, light/dark shifting induced the formation of smaller and more compact fungal pellets, suggesting a new effective strategy for large-scale production of HA in mycelium cultures. The light/dark shift up-regulated the expression levels of two reactive oxygen species (ROS) related genes including superoxide-generating NADPH oxidase (Nox) and cytochrome c peroxidase (CCP), and induced the generation of ROS. With the treatment of vitamin C, we found that ROS was involved in the up-regulated expression of key biosynthetical genes for hypocrellins and improved HA production. These results provide a basis for understanding the influence of light/dark shift on fungal metabolism and the application of a novel strategy for enhancing HA production in submerged Shiraia cultures.
Asunto(s)
Ascomicetos/química , Regulación Fúngica de la Expresión Génica/efectos de la radiación , Microbiología Industrial/métodos , Luz , Perileno/análogos & derivados , Quinonas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Ascomicetos/metabolismo , Ascomicetos/efectos de la radiación , Micelio/crecimiento & desarrollo , Micelio/metabolismo , Micelio/efectos de la radiación , Perileno/química , Perileno/metabolismo , Fenol , Fotoperiodo , Quinonas/química , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
The aim of this study was to analyse how protracted exposure to X-rays delivered at low dose rates of 0.0032-0.052 kGy h-1 affects the survival and metabolic activity of two microfungi capable of melanogenesis: fast-growing Cryptococcus neoformans (CN) and slow-growing Cryomyces antarcticus (CA). Melanized CN and CA cells survived the protracted exposure better than non-melanized ones, which was consistent with previous reports on the radioprotective role of melanin in these fungi after high dose rate exposures. The survival data were described by the linear quadratic dose response model. The XTT metabolic profiles were practically identical for melanized CN and CA with activity dose-dependent increasing: no changes in the activity of the non-melanized CN and CA were recorded by this assay. In contrast, the MTT assay, which measures the intracellular energy-related processes, recorded an increase in activity of non-melanized CN and CA cells, but not in their melanized counterparts. This could reflect intensive repair processes initiated by the non-melanized cells post exposure. This study suggests that differences in radiation responses between melanized and non-melanized fungal cells occur over a wide range of radiation dose rates.