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1.
Food Microbiol ; 82: 82-88, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31027823

RESUMO

Different methods have been applied in controlling contamination of foods and feeds by the carcinogenic fungal toxin, aflatoxin, but nevertheless the problem remains pervasive in developing countries. Curcumin is a natural polyphenolic compound from the spice turmeric (Curcuma longa L.) that has been identified as an efficient photosensitiser for inactivation of Aspergillus flavus conidia. Curcumin mediated photoinactivation of A. flavus has revealed the potential of this technology to be an effective method for reducing population density of the aflatoxin-producing fungus in foods. This study demonstrates the influence of pH and temperature on efficiency of photoinactivation of the fungus and how treating spore-contaminated maize kernels affects aflatoxin production. The results show the efficiency of curcumin mediated photoinactivation of fungal conidia and hyphae were not affected by temperatures between 15 and 35 °C or pH range of 1.5-9.0. The production of aflatoxin B1 was significantly lower (p < 0.05), with an average of 82.4 µg/kg as compared to up to 305.9 µg/kg observed in untreated maize kept under similar conditions. The results of this study indicate that curcumin mediated photosensitization can potentially be applied under simple environmental conditions to achieve significant reduction of post-harvest contamination of aflatoxin B1 in maize.


Assuntos
Aflatoxina B1/metabolismo , Aspergillus flavus/efeitos dos fármacos , Aspergillus flavus/efeitos da radiação , Curcumina/farmacologia , Transtornos de Fotossensibilidade , Zea mays/microbiologia , Concentração de Íons de Hidrogênio , Hifas/efeitos dos fármacos , Hifas/efeitos da radiação , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/efeitos da radiação , Temperatura Ambiente
2.
mBio ; 10(2)2019 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-30967462

RESUMO

The filamentous fungus Alternaria alternata is a common postharvest contaminant of food and feed, and some strains are plant pathogens. Many processes in A. alternata are triggered by light. Interestingly, blue light inhibits sporulation, and red light reverses the effect, suggesting interactions between light-sensing systems. The genome encodes a phytochrome (FphA), a white collar 1 (WC-1) orthologue (LreA), an opsin (NopA), and a cryptochrome (CryA) as putative photoreceptors. Here, we investigated the role of FphA and LreA and the interplay with the high-osmolarity glycerol (HOG) mitogen-activated protein (MAP) kinase pathway. We created loss-of function mutations for fphA, lreA, and hogA using CRISPR-Cas9 technology. Sporulation was reduced in all three mutant strains already in the dark, suggesting functions of the photoreceptors FphA and LreA independent of light perception. Germination of conidia was delayed in red, blue, green, and far-red light. We found that light induction of ccgA (clock-controlled gene in Neurospora crassa and light-induced gene in Aspergillus nidulans) and the catalase gene catA depended on FphA, LreA, and HogA. Light induction of ferA (a putative ferrochelatase gene) and bliC (bli-3, light regulated, unknown function) required LreA and HogA but not FphA. Blue- and green-light stimulation of alternariol formation depended on LreA. A lack of FphA or LreA led to enhanced resistance toward oxidative stress due to the upregulation of catalases and superoxide dismutases. Light activation of FphA resulted in increased phosphorylation and nuclear accumulation of HogA. Our results show that germination, sporulation, and secondary metabolism are light regulated in A. alternata with distinct and overlapping roles of blue- and red-light photosensors.IMPORTANCE Light controls many processes in filamentous fungi. The study of light regulation in a number of model organisms revealed an unexpected complexity. Although the molecular components for light sensing appear to be widely conserved in fungal genomes, the regulatory circuits and the sensitivity of certain species toward specific wavelengths seem different. In N. crassa, most light responses are triggered by blue light, whereas in A. nidulans, red light plays a dominant role. In Alternaria alternata, both blue and red light appear to be important. In A. alternata, photoreceptors control morphogenetic pathways, the homeostasis of reactive oxygen species, and the production of secondary metabolites. On the other hand, high-osmolarity sensing required FphA and LreA, indicating a sophisticated cross talk between light and stress signaling.


Assuntos
Alternaria/crescimento & desenvolvimento , Alternaria/efeitos da radiação , Luz , Fotorreceptores Microbianos/metabolismo , Fitocromo/metabolismo , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação , Alternaria/genética , Alternaria/metabolismo , Regulação Fúngica da Expressão Gênica/efeitos da radiação , Técnicas de Inativação de Genes , Redes Reguladoras de Genes , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Transdução de Sinais , Esporos Fúngicos/genética , Esporos Fúngicos/metabolismo
3.
Artigo em Inglês | MEDLINE | ID: mdl-30917597

RESUMO

Damp indoor environments contaminated with different mold species may contribute to the development and exacerbation of respiratory illnesses. Human bronchial epithelial BEAS-2B cells were exposed to X-ray treated spores and hyphal fragments from pure cultures of Aspergillus fumigatus, Penicillum chrysogenum, Aspergillus versicolor and Stachybotrys chartarum. Hyphal fragments of A. fumigatus and P. chrysogenum induced expression and release of the pro-inflammatory cytokine interleukin (IL)-6 and the chemokine IL-8, while none of the other hyphal preparations had effects. Hyphal fragments from A. fumigatus and P. chrysogenum also increased the expression of IL-1α, IL-1ß and tumor necrosis factor (TNF)-α, but these cytokines were not released. X-ray treated spores had little or no inflammatory potential. Attenuating Toll-like receptor (TLR)-2 by blocking antibodies strongly reduced the A. fumigatus and P. chrysogenum hyphae-induced IL-6 and IL-8 release, whereas TLR4 antagonist treatment was without effects. Untreated A. fumigatus spores formed hyphae and triggered expression of pro-inflammatory genes with similarities to the effects of hyphal fragments. In conclusion, while X-ray treated spores induced no pro-inflammatory responses, hyphal fragments of A. fumigatus and P. chrysogenum enhanced a TLR2-dependent expression and release of IL-6 and IL-8.


Assuntos
Aspergillus , Células Epiteliais/imunologia , Hifas , Penicillium , Esporos Fúngicos , Stachybotrys , Poluição do Ar em Ambientes Fechados/efeitos adversos , Linhagem Celular , Citocinas/imunologia , Humanos , Hifas/efeitos da radiação , Esporos Fúngicos/efeitos da radiação , Receptor 2 Toll-Like/imunologia , Raios X
4.
Food Microbiol ; 81: 108-114, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30910081

RESUMO

Fungi are able to grow on diverse food products and contribute to food spoilage worldwide causing food loss. Consumers prefer freshly squeezed fruit juices, however, the shelf life of these juices is limited due to outgrowth of yeast and fungi. The shelf life of pulsed electric field (PEF) treated juice can be extended from 8 days up to a few weeks before spoilage by moulds becomes apparent. Conidia produced by three Penicillium ssp. (Penicillium expansum, Penicillium buchwaldii and Penicillium bialowiezense), previously isolated from spoiled PEF treated fruit juice and smoothie, were characterized for resistance towards selected mild physical processing techniques in orange juice and toward sanitizers on surfaces. The results show that Penicillium spp. conidia are susceptible to mild heat, high pressure pasteurization (HPP), PEF, cold atmospheric plasma (CAP), UV, and chemical sanitizers chlorine dioxide and hypochlorite albeit with different susceptibility. Treatment with mild heat, HPP, PEF, or chlorine dioxide reduced conidia by more than 5 log. For hypochlorite, UV, and CAP the reduction was between 1 and 3 log. Together, this study provides data for the development of intervention strategies to eliminate spoilage mould conidia in fruit juices.


Assuntos
Desinfecção/métodos , Conservação de Alimentos/métodos , Sucos de Frutas e Vegetais/microbiologia , Penicillium/efeitos dos fármacos , Penicillium/efeitos da radiação , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/efeitos da radiação , Compostos Clorados/farmacologia , Citrus sinensis , Eletricidade , Manipulação de Alimentos , Armazenamento de Alimentos , Temperatura Alta , Ácido Hipocloroso/farmacologia , Testes de Sensibilidade Microbiana , Óxidos/farmacologia , Pasteurização/métodos , Penicillium/crescimento & desenvolvimento , Penicillium/isolamento & purificação , Gases em Plasma/farmacologia , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/isolamento & purificação , Raios Ultravioleta
5.
Fungal Biol ; 123(3): 218-230, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30798877

RESUMO

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.


Assuntos
Ascomicetos/crescimento & desenvolvimento , Ascomicetos/efeitos da radiação , Desoxirribodipirimidina Fotoliase/biossíntese , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação , Transcrição Genética , Raios Ultravioleta , Reparo do DNA/efeitos da radiação , Hordeum/microbiologia , Luz , Doenças das Plantas/microbiologia
6.
Pest Manag Sci ; 75(2): 556-563, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30221461

RESUMO

BACKGROUND: Solar radiation is assumed to be a major factor limiting the efficacy of entomopathogenic fungi used as biocontrol agents in open field applications. We evaluated 12 natural UV-protective co-formulants for their effect on the survival of UV-exposed Beauveria bassiana spores on agar plates, colza leaf discs and in the field. RESULTS: Colony-forming unit (CFU) counts of unformulated conidia on agar plates and leaf discs dropped to ≤ 50% after exposure to UV radiation. The highest UV protection was achieved with humic acid, which provided > 90% protection of UV-B-exposed conidia in laboratory experiments. In the field, 10% humic acid increased spore persistence up to 87% at 7 days after application. Sesame and colza oil also provided high UV protection in both assays (> 73% and > 70%, respectively). CONCLUSIONS: This study shows that it is possible to increase the persistence of B. bassiana spores under exposure to UV radiation by formulation with natural UV-protective additives. UV protectants might, therefore, increase the efficacy of entomopathogenic fungi as biocontrol agents in open field applications. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Beauveria/efeitos dos fármacos , Beauveria/efeitos da radiação , Controle Biológico de Vetores/métodos , Protetores contra Radiação/farmacologia , Raios Ultravioleta/efeitos adversos , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/efeitos da radiação
7.
Biocontrol Sci ; 23(4): 177-186, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30584204

RESUMO

In storage of modern museums, collections are packed and stored with acid-free paper-based materials for keeping safe and stable conditions. Direct contact of fungal contaminated packing and storing materials with the collections is concerned about expanding of infection in storage facilities. In this study, fungicidal effects of UV light irradiation on the materials such as archival board and Japanese tissue paper contaminated with Penicilliun commune and Chaetomium globosum were tested. The analyzed materials were divided into two groups; Group 1 was examined with 20 µl of spore suspensions of fungi (106 cfu/ml) ; and Group 2 was tested on Czapek- Dox agar medium modified without sugar and inoculated with 100 µl of the spore suspensions of fungi (106 cfu/ml) . Six doses of UV irradiation were examined on Group 1 and five doses on Group 2 in addition to control. The assessment was done by using 1) adenosine triphosphate (ATP) bioluminescence assay and double staining to determine the cell viability; 2) observation under light microscope to evaluate morphophysiological change of tested fungi (spores and hyphae) . Because of the thinness and high transparency of tissue paper, UV irradiations were highly efficient to fungicide its fungal contamination compared with archival board. In spite of the high resistance of C. globosum spores, the rate of growth was slow, and with a little amount of perithecia or fruiting bodies and a high amount of ycelium (which damaged rapidly through UV irradiation) . This may be due to a low relative humidity of the incubation environment. Minimum dosage of UV irradiation with fungicidal effectiveness against all fungal contamination was estimated as 118 J/cm2.


Assuntos
Chaetomium/efeitos da radiação , Museus , Penicillium/efeitos da radiação , Esporos Fúngicos/efeitos da radiação , Raios Ultravioleta , Contaminação de Equipamentos , Embalagem de Produtos
8.
J Microbiol ; 56(12): 893-901, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30361976

RESUMO

Fungal development and secondary metabolism are closely associated via the activities of the fungal NK-kB-type velvet regulators that are highly conserved in filamentous fungi. Here, we investigated the roles of the velvet genes in the aflatoxigenic fungus Aspergillus flavus. Distinct from other Aspergillus species, the A. flavus genome contains five velvet genes, veA, velB, velC, velD, and vosA. The deletion of velD blocks the production of aflatoxin B1, but does not affect the formation of sclerotia. Expression analyses revealed that vosA and velB mRNAs accumulated at high levels during the late phase of asexual development and in conidia. The absence of vosA or velB decreased the content of conidial trehalose and the tolerance of conidia to the thermal and UV stresses. In addition, double mutant analyses demonstrated that VosA and VelB play an inter-dependent role in trehalose biosynthesis and conidial stress tolerance. Together with the findings of previous studies, the results of the present study suggest that the velvet regulators play the conserved and vital role in sporogenesis, conidial trehalose biogenesis, stress tolerance, and aflatoxin biosynthesis in A. flavus.


Assuntos
Aspergillus flavus/genética , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Genes Fúngicos/genética , Aflatoxina B1/biossíntese , Aflatoxinas , Aspergillus flavus/metabolismo , Proteínas Fúngicas/metabolismo , Deleção de Genes , Fenótipo , RNA Mensageiro/metabolismo , Tolerância a Radiação , Metabolismo Secundário , Esporos Fúngicos/genética , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação , Estresse Fisiológico , Transcriptoma , Trealose/metabolismo , Raios Ultravioleta/efeitos adversos
9.
World J Microbiol Biotechnol ; 34(10): 143, 2018 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-30203172

RESUMO

Bacterial and fungal spore contamination in different industries has a greater economic impact. Because of the remarkable resistance of spores to most physical and chemical microbicidal agents, their inactivation need special attention during sterilization processes. Heat and chemical sporicides are not always well suited for different sterilization/decontamination applications and carries inherent risks. In recent years, novel nonthermal agents including nonthermal plasmas are emerging as effective sporicides against a broad spectrum of bacterial and fungal spores. The present review discusses various aspects related to the inactivation of spores using nonthermal plasmas. Different types of both low pressure plasmas (e.g., capacitively coupled plasma and microwave plasma) and atmospheric pressure plasmas (e.g., dielectric barrier discharges, corona discharges, arc discharges, radio-frequency-driven plasma jet) have been successfully applied to destroy spores of economic significance. Plasma agents contributing to sporicidal activity and their mode of action in inactivation are discussed. In addition, information on factors that affect the sporicidal action of nonthermal plasmas is included.


Assuntos
Esporos Bacterianos/efeitos da radiação , Esporos Fúngicos/efeitos da radiação , Esterilização/instrumentação , Esterilização/métodos , Temperatura Baixa , Descontaminação/métodos , Umidade , Viabilidade Microbiana , Pressão , Esporos , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Fúngicos/crescimento & desenvolvimento , Propriedades de Superfície
10.
J Invertebr Pathol ; 157: 32-35, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30017952

RESUMO

The isolate ARSEF 324 of Metarhizium acridum is very tolerant to UV-B radiation and heat, but the intrinsic traits behind the extreme tolerance of this isolate to both stress conditions have not been elucidated. Because trehalose and mannitol are documented stress reducers in fungi, we investigated the accumulation of these compounds in conidia of ARSEF 324 compared with the accumulation of these two compounds in conidia of M. robertsii (ARSEF 23 and ARSEF 2575), which are considerably more susceptible to UV-B radiation and heat than ARSEF 324. Conidia of ARSEF 324 produced on potato dextrose agar plus yeast extract accumulated two-fold more trehalose and mannitol than conidia of ARSEF 23 and ARSEF 2575 produced on the same medium. The high accumulation of trehalose and mannitol in conidia of ARSEF 324 suggests one mechanism that it uses to attain its high tolerance to UV-B radiation and heat.


Assuntos
Manitol/metabolismo , Metarhizium/metabolismo , Termotolerância/fisiologia , Trealose/metabolismo , Raios Ultravioleta , Metarhizium/efeitos da radiação , Esporos Fúngicos/metabolismo , Esporos Fúngicos/efeitos da radiação
11.
Can J Microbiol ; 64(11): 856-864, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29906398

RESUMO

The effect of light on the binding of Ca2+ to mycelia and to cell walls isolated from aerial mycelia of three strains of Trichoderma spp. was studied. Two independent methods were used to measure the total Ca2+ content in mycelia and the Ca2+ bound to cell walls isolated from aerial mycelia. The results of these methods showed that the light-induced formation and maturation of conidia in Trichoderma spp. is accompanied by increased Ca2+ deposition in mycelia and cell walls. Moreover, the cultivation of Trichoderma atroviride F-534 in the presence of 45Ca2+ under circadian illumination showed that radioactivity was exclusively localized in the light-induced conidial rings of aerial mycelia. The fluorescence microscopy of chlortetracycline-stained mycelia showed that the major fraction of Ca2+ was accumulated in conidia and fructification structures, or some intracellular compartments in T. atroviride F-534 grown under circadian illumination, while only a limited amount of Ca2+ was associated with hyphal surfaces. In addition, the study of 45Ca2+ binding to cell walls revealed that T. atroviride F-534 displays both increased 45Ca2+ binding capacity and elevated affinity to 45Ca2+ binding upon illumination. The results indicate that conidia formation and (or) maturation is associated with changes in Ca2+ homeostasis.


Assuntos
Cálcio/metabolismo , Parede Celular/metabolismo , Luz , Esporos Fúngicos/efeitos da radiação , Trichoderma/fisiologia , Regulação Fúngica da Expressão Gênica/fisiologia , Hifas/metabolismo , Microscopia de Fluorescência , Micélio/metabolismo
12.
J Med Entomol ; 55(5): 1330-1333, 2018 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-29750411

RESUMO

Ultraviolet (UV) radiation is a key limiting factor for biological pest control with entomopathogenic fungi. While little is known about the impact of UV on Metarhizium anisopliae Metchnikoff (Sorokin) (Hypocreales: Clavicipitaceae) conidia in aquatic mosquito-breeding sites, this study determined the effect of UV-B on the viability and virulence of M. anisopliae sensu lato (s.l.) strain IP 46 in the laboratory against Aedes aegypti (L.) (Diptera: Culicidae) larvae. Conidia were treated in cups under defined water depths (0, 1, 2, and 3 cm) to six different UV-B doses (0, 0.657, 1.971, 3.942, 7.884, 11.826, or 15.768 kJ m-2) at 27 ± 2°C. The ability of treated conidia to germinate up to 24 h postexposure on PDAY + benomyl + chloramphenicol medium at 25 ± 1°C was adversely affected by higher doses of UV-B radiation regardless of the water depth. Germination, however, did not fall below 70% regardless of the test conditions. In fact, conidial virulence against second-instar larvae was not affected by either the water depth (F3,84 = 0.3, P = 0.85) or any tested levels of UV-B radiation (F6,21 ≤ 1.2, P ≥ 0.39) including those distinctly higher than might be expected for tropical sites. These findings strengthen previous observations that IP 46 has significant potential for use against A. aegypti larvae, even when exposed to elevated UV-B irradiance levels in the small breeding sites that are common for this important vector.


Assuntos
Aedes , Larva , Metarhizium/efeitos da radiação , Controle de Mosquitos , Esporos Fúngicos/efeitos da radiação , Animais , Raios Ultravioleta
13.
Photochem Photobiol ; 94(5): 1003-1009, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29700835

RESUMO

Penicillium digitatum (Pers.:Fr.) Sacc. is the main fungus causing postharvest losses in citrus fruits. Previous work showed the potential of LED blue light (LBL) in controlling P. digitatum growth. Here, we have investigated whether LBL alters the ability of this fungus to infect citrus fruits. Before fruit infection, Petri plates inoculated with the same conidia concentration were held under darkness (control) or LBL (100 µmol m-2 s-1 ) for 8 d (continuous light), or were treated with the same LBL for 3 d and then shifted to darkness for 5 d (non-continuous light). Spores from cultures exposed to continuous light showed very low capacity to germinate (1.8% respect to control) but a high viability and a similar morphology and ability to infect the fruits than spores from control cultures. The number of spores produced in plates exposed to non-continuous light was slightly lower than in control plates, but they showed much lower viability and lower capacity to infect the fruits. This effect was more likely related to aberrant morphology of spores, which formed aggregates, than to its metabolic activity or its ability to produce ethylene that might contribute to destroy natural defense barriers from the fruit.


Assuntos
Citrus/microbiologia , Penicillium/patogenicidade , Penicillium/efeitos da radiação , Doenças das Plantas/microbiologia , Virulência/efeitos da radiação , Dióxido de Carbono/metabolismo , Escuridão , Etilenos/metabolismo , Germinação/efeitos da radiação , Luz , Penicillium/crescimento & desenvolvimento , Penicillium/fisiologia , Esporos Fúngicos/efeitos da radiação
14.
Mycoses ; 61(6): 393-399, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29460305

RESUMO

Recently, we had shown that conidia-derived growth of many dermatophytes can be inhibited by curcumin plus exposure to visible light. This method of photo inactivation should be developed further aiming for an option to stop mycelial growth in superficial tinea. Wells of microtitre plates were inoculated with either mycelial or conidial elements collected from 5 strains of Trichophyton rubrum. Then either micellar curcumin or curcumin dissolved with DMSO was added and after 20 min the wells were filled up with Sabouraud broth. Thereafter the assays were irradiated once with visible light (wave length 420 nm, 20 J/cm2 ) and fungal growth was monitored photometrically. Identical effects were measured with conidia and mycelial elements of all 5 T. rubrum strains. Curcumin dissolved with DMSO plus irradiation had a marked dose-dependent inhibitory effect on fungal growth that was almost complete with 5.0 mg/L (P < .01) over a period of 9 days. In contrast, the same procedure with micellar curcumin had no inhibitory effect on growth obtained from conidia or mycelial elements. Mycelial elements of T. rubrum and its conidia are equally sensitive to photochemical inactivation with curcumin and the galenic compounding of curcumin is essential to achieve this photochemical effect.


Assuntos
Curcumina/farmacologia , Luz , Micélio/efeitos dos fármacos , Esporos Fúngicos/efeitos dos fármacos , Trichophyton/efeitos dos fármacos , Curcumina/química , Dimetil Sulfóxido/farmacologia , Humanos , Micélio/crescimento & desenvolvimento , Micélio/efeitos da radiação , Processos Fotoquímicos , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação , Tinha/microbiologia , Trichophyton/crescimento & desenvolvimento , Trichophyton/isolamento & purificação , Trichophyton/efeitos da radiação
15.
J Appl Microbiol ; 125(1): 159-171, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29473986

RESUMO

AIMS: The effect of nutritional supplementation of two Metarhizium species with riboflavin (Rb) during production of conidia was evaluated on (i) conidial tolerance (based on germination) to UV-B radiation and on (ii) conidial expression following UV-B irradiation, of enzymes known to be active in photoreactivation, viz., photolyase (Phr), laccase (Lac) and polyketide synthase (Pks). METHODS AND RESULTS: Metarhizium acridum (ARSEF 324) and Metarhizium robertsii (ARSEF 2575) were grown either on (i) potato dextrose agar medium (PDA), (ii) PDA supplemented with 1% yeast extract (PDAY), (iii) PDA supplemented with Rb (PDA+Rb), or (iv) PDAY supplemented with Rb (PDAY+Rb). Resulting conidia were exposed to 866·7 mW m-2 of UV-B Quaite-weighted irradiance to total doses of 3·9 or 6·24 kJ m-2 . Some conidia also were exposed to 16 klux of white light (WL) after being irradiated, or not, with UV-B to investigate the role of possible photoreactivation. Relative germination of conidia produced on PDA+Rb (regardless Rb concentration) or on PDAY and exposed to UV-B was higher compared to conidia cultivated on PDA without Rb supplement, or to conidia suspended in Rb solution immediately prior to UV-B exposure. The expression of MaLac3 and MaPks2 for M. acridum, as well as MrPhr2, MrLac1, MrLac2 and MrLac3 for M. robertsii was higher when the isolates were cultivated on PDA+Rb and exposed to UV-B followed by exposure to WL, or exposed to WL only. CONCLUSIONS: Rb in culture medium increases the UV-B tolerance of M. robertsii and M. acridum conidia, and which may be related to increased expression of Phr, Lac and Pks genes in these conidia. SIGNIFICANCE AND IMPACT OF THE STUDY: The enhanced UV-B tolerance of Metarhizium spp. conidia produced on Rb-enriched media may improve the effectiveness of these fungi in biological control programs.


Assuntos
Metarhizium , Riboflavina/farmacologia , Esporos Fúngicos , Regulação para Cima/efeitos dos fármacos , Desoxirribodipirimidina Fotoliase/genética , Desoxirribodipirimidina Fotoliase/metabolismo , Lacase/genética , Lacase/metabolismo , Metarhizium/efeitos dos fármacos , Metarhizium/enzimologia , Metarhizium/genética , Metarhizium/efeitos da radiação , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/efeitos da radiação , Raios Ultravioleta
16.
J Sci Food Agric ; 98(7): 2770-2776, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29119563

RESUMO

BACKGROUND: Mung bean is a rich source of protein, carbohydrates and fiber content. It also exhibits a high level of antioxidant activity due to the presence of phenolic compounds. Aspergillus flavus and A. niger are the two major fungal strains associated with stored mung bean that lead to post-harvest losses of grains and also cause serious health risks to human beings. Thus there is a need to explore an economical decontamination method that can be used without affecting the biochemical parameters of grains. RESULTS: It was observed that infrared (IR) treatment of mung bean surface up to 70 °C for 5 min at an intensity of 0.299 kW m-2 led to complete visible inhibition of fungal growth. Scanning electron microscopy revealed that surface irregularities and physical disruption of spores coat are the major reasons behind the inactivation of IR-treated fungal spores. It was also reported that IR treatment up to 70 °C for 5 min does not cause any negative impact on the biochemical and physical properties of mung bean. CONCLUSION: From the results of the present study, it was concluded that IR treatment at 70 °C for 5 min using an IR source having an intensity of 0.299 kW m-2 can be successfully used as a method of fungal decontamination. The fungal spore population was reduced (approximately 5.3 log10 CFU g-1 reductions) without significantly altering the biochemical and physical properties of grains. © 2017 Society of Chemical Industry.


Assuntos
Aspergillus flavus/efeitos da radiação , Aspergillus niger/efeitos da radiação , Contaminação de Alimentos/prevenção & controle , Irradiação de Alimentos/métodos , Doenças das Plantas/microbiologia , Vigna/microbiologia , Aspergillus flavus/crescimento & desenvolvimento , Aspergillus niger/crescimento & desenvolvimento , Raios Infravermelhos , Sementes/microbiologia , Sementes/efeitos da radiação , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação , Vigna/efeitos da radiação
17.
Med Mycol ; 56(7): 877-883, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29228375

RESUMO

This study verified the influence of different temperatures on P. insidiosum in vitro zoosporogenesis. P. insidiosum isolates (n = 26) were submitted to zoosporogenesis and incubated at 5°C, 15°C, 20°C and 37°C (1st stage). Grass fragments were evaluated under optical microscopy at 4, 8, and 24 hours of incubation. Afterward, all isolates were incubated at 37°C and assessed at the same periods of time (2nd stage). The development of hyphae, presence of vesicles, zoosporangia and zoospores were checked. Only the presence of short hyphae was observed at 5°C. At 15°C, the hyphae were either under development or elongated and two isolates produced zoospores. When the isolates were submitted to 20°C for 4 hours, the presence of long and mycelial hyphae, vesicles, zoosporangia and zoospores was observed, which also happened at the other periods evaluated. In the second stage, the isolates which were initially at 5°C and 15°C evidenced long developing hyphae with the presence of vesicles, zoosporangia, and zoospores within 4 hours of incubation, and these characteristics were kept at the other evaluated periods. The isolates kept at 37°C showed evident zoosporogenesis in the first 4 hours of evaluation. It was concluded that temperatures of 20°C and 37°C support P. insidiosum zoosporogenesis process. On the other hand, 5°C and 15°C temperatures do not kill the microorganism.


Assuntos
Pythium/crescimento & desenvolvimento , Pythium/efeitos da radiação , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação , Hifas/citologia , Hifas/crescimento & desenvolvimento , Hifas/efeitos da radiação , Microscopia , Pythium/citologia , Esporos Fúngicos/citologia , Temperatura Ambiente
18.
J Photochem Photobiol B ; 178: 631-640, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29278857

RESUMO

Controlled environment chamber experiments at Petri dish level were conducted to examine the wavelength and dose dependent efficacy of ultraviolet (UV) radiation, the recovery action potential of optical radiation applied concomitantly/subsequently to effective UV treatment, and the lapse time between UV treatment and subsequent exposure to recovery wavelength on germination efficiency of Oidium neolycopersici conidia. Conidia of eight- to nine-day-old colonies were dusted on water agar surface in Petri dishes and exposed to UV treatments (without lid). Immediately after UV treatments, Petri dishes were sealed and incubated in darkness or differing optical environments generated using seven different radiation sources (range 290nm to 780nm). Twenty-four hours after UV treatment, fifty conidia from each sample were assessed for germination. Compared to non-UV controls, <10% of the conidia germinated after 30s of exposure to 254nm or 283nm UV and subsequent dark incubation. Conidia germination was almost negligible if the exposure duration increased to 4min. Germination was about 60% with broad spectrum UV after 1min of exposure, and about 35% after 2 to 4min of exposure. There was no reduction of conidia germination with the exposure of ≤4min with 310nm. With the tested wavelength and dose ranges, germination recovery was effective in the 350nm to 500nm range. Germination efficiency of conidia treated with effective UV was significantly higher (>73%) if incubated subsequently in the 350nm to 500nm range (germination recovery). Furthermore, germination recovery depends on the characteristics of UV treatment (wavelength, and duration of exposure) and the lapse time between UV treatment and subsequent exposure to optical radiation in the recovery range. The findings of this study provide key criteria for wavelength selection, combination and application time in the optical radiation range, enabling improved design of optical based management strategies against powdery mildews.


Assuntos
Ascomicetos/fisiologia , Esporos Fúngicos/efeitos da radiação , Raios Ultravioleta , Ascomicetos/crescimento & desenvolvimento , Ascomicetos/efeitos da radiação , Lycopersicon esculentum/microbiologia , Fatores de Tempo
19.
Lasers Med Sci ; 33(4): 927-933, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-28378259

RESUMO

Onychomycoses are fungal infections of the fingernails or toenails having a prevalence of 3% among adults and accounts for 50% of nail infections. It is caused by dermatophytes, non-dermatophyte filamentous fungi, and yeasts. Compressions and microtraumas significantly contribute to onychomycosis. Laser and photodynamic therapies are being proposed to treat onychomycosis. Laser light (1064 nm) was used to treat onychomycosis in 156 affected toenails. Patients were clinically followed up for 9 months after treatment. Microbiological detection of fungal presence in lesions was accomplished. A total of 116 samples allowed the isolation of at least a fungus. Most of nails were affected in more than two thirds surface (some of them in the full surface). In 85% of cases, after 18 months of the onset of treatment, culture turned negative. After 3 months months, only five patients were completely symptom-free with negative culture. In 25 patients, only after 6 months, the absence of symptoms was achieved and the cultures negativized; in 29 patients, 9 months were required. No noticeable adverse effects were reported. This study reinforces previous works suggesting the applicability of laser therapies to treat toenail onychomycosis.


Assuntos
Dermatoses do Pé/radioterapia , Onicomicose/radioterapia , Adulto , Feminino , Dermatoses do Pé/microbiologia , Humanos , Masculino , Pessoa de Meia-Idade , Unhas/microbiologia , Onicomicose/microbiologia , Esporos Fúngicos/efeitos da radiação , Esporos Fúngicos/ultraestrutura , Resultado do Tratamento , Trichophyton/efeitos da radiação , Trichophyton/ultraestrutura
20.
mBio ; 8(6)2017 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-29259092

RESUMO

Although meiosis in warm-blooded organisms takes place in a narrow temperature range, meiosis in many organisms occurs over a wide variety of temperatures. We analyzed the properties of meiosis in the yeast Saccharomyces cerevisiae in cells sporulated at 14°C, 30°C, or 37°C. Using comparative-genomic-hybridization microarrays, we examined the distribution of Spo11-generated meiosis-specific double-stranded DNA breaks throughout the genome. Although there were between 300 and 400 regions of the genome with high levels of recombination (hot spots) observed at each temperature, only about 20% of these hot spots were found to have occurred independently of the temperature. In S. cerevisiae, regions near the telomeres and centromeres tend to have low levels of meiotic recombination. This tendency was observed in cells sporulated at 14°C and 30°C, but not at 37°C. Thus, the temperature of sporulation in yeast affects some global property of chromosome structure relevant to meiotic recombination. Using single-nucleotide polymorphism (SNP)-specific whole-genome microarrays, we also examined crossovers and their associated gene conversion events as well as gene conversion events that were unassociated with crossovers in all four spores of tetrads obtained by sporulation of diploids at 14°C, 30°C, or 37°C. Although tetrads from cells sporulated at 30°C had slightly (20%) more crossovers than those derived from cells sporulated at the other two temperatures, spore viability was good at all three temperatures. Thus, despite temperature-induced variation in the genetic maps, yeast cells produce viable haploid products at a wide variety of sporulation temperatures.IMPORTANCE In the yeast Saccharomyces cerevisiae, recombination is usually studied in cells that undergo meiosis at 25°C or 30°C. In a genome-wide analysis, we showed that the locations of genomic regions with high and low levels of meiotic recombination (hot spots and cold spots, respectively) differed dramatically in cells sporulated at 14°C, 30°C, and 37°C. Thus, in yeast, and likely in other non-warm-blooded organisms, genetic maps are strongly affected by the environment.


Assuntos
Meiose/efeitos da radiação , Recombinação Genética/efeitos da radiação , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/efeitos da radiação , Temperatura Ambiente , Hibridização Genômica Comparativa , Quebras de DNA de Cadeia Dupla , Análise em Microsséries , Viabilidade Microbiana/efeitos da radiação , Saccharomyces cerevisiae/crescimento & desenvolvimento , Esporos Fúngicos/genética , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação
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