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1.
Sci Rep ; 12(1): 12142, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35840596

RESUMO

Melanin-containing fungi (black molds) have the capacity to thrive under extreme environmental conditions such as the elevated radiation levels inside the former Chernobyl reactors. These fungi have been hypothesized to grow toward and use gamma radiation as an energy source, but the literature does not clearly address which energies of the electromagnetic spectrum, if any, positively affect fungal growth. The goal of this work was to characterize the response of non-melanized and melanized fungi to two distinct electromagnetic wavelengths, i.e., ultraviolet (UV) and gamma ray, keeping absorption and other potentially confounding variables constant. Exposure to UV or gamma radiation induced significant changes in fungi pigmentation, but not growth rate of Cladosporium cladosporioides and Paecilomyces variotii. Specifically, increased pigmentation of both fungi was observed in samples exposed to UV, while decreased pigmentation was observed for gamma-irradiated samples. These results provide new insights into the role of electromagnetic energies on growth of fungi and provide an impetus to examine additional energies and types of radiation to develop a fundamental understanding of this phenomenon.


Assuntos
Cladosporium , Raios gama , Pigmentação , Raios Ultravioleta , Byssochlamys/crescimento & desenvolvimento , Byssochlamys/efeitos da radiação , Cladosporium/crescimento & desenvolvimento , Cladosporium/efeitos da radiação , Melaninas/metabolismo , Pigmentação/efeitos da radiação
2.
J Agric Food Chem ; 70(15): 4658-4666, 2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35384660

RESUMO

Four new carotane sesquiterpenoids, byssocarotins A-D (1-4), two new nor-sesquiterpenoids, byssofarnesin (5) and byssosesquicarin (6), and three new polyketides, byssoketides A and B (7 and 8) and (8R)-paecilocin A (9a), were obtained from a macroalga-associated strain (RR-dl-2-13) of the fungus Byssochlamys spectabilis. These isolates were identified by a combination of spectroscopic methods, including mass spectroscopy, nuclear magnetic resonance, electronic circular dichroism, and X-ray diffraction. Compounds 1-4 greatly contribute to the diversity of rarely occurring 2,15-epoxycarotane sesquiterpenoids, while 5 and 6 are degradation products of farnesane and sesquicarane precursors, respectively. Compound 7 is a structurally unique furan fatty acid derivative that possesses an aldehyde group and a large conjugated unit, and 8 features a hemiketal group. During antimicrobial assays, 8 showed antagonism against the phytopathogenic fungi Glomerella cingulata, Fusarium oxysporum f. sp. cucumerium, and F. oxysporum f. sp. cubense and the marine-derived bacteria Vibrio parahaemolyticus and V. harveyi with MIC values of 13 to 50 µg/mL.


Assuntos
Policetídeos , Antibacterianos/química , Antibacterianos/farmacologia , Byssochlamys , Fungos , Estrutura Molecular , Policetídeos/química , Terpenos/farmacologia
3.
Curr Biol ; 32(5): 937-950.e5, 2022 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-35063120

RESUMO

The horizontal transfer of large gene clusters by mobile elements is a key driver of prokaryotic adaptation in response to environmental stresses. Eukaryotic microbes face similar stresses; however, a parallel role for mobile elements has not been established. A stress faced by many microorganisms is toxic metal ions in their environment. In fungi, identified mechanisms for protection against metals generally rely on genes that are dispersed within an organism's genome. Here, we discover a large (∼85 kb) region that confers tolerance to five metal/metalloid ions (arsenate, cadmium, copper, lead, and zinc) in the genomes of some, but not all, strains of a fungus, Paecilomyces variotii. We name this region HEPHAESTUS (Hφ) and present evidence that it is mobile within the P. variotii genome with features characteristic of a transposable element. HEPHAESTUS contains the greatest complement of host-beneficial genes carried by a transposable element in eukaryotes, suggesting that eukaryotic transposable elements might play a role analogous to bacteria in the horizontal transfer of large regions of host-beneficial DNA. Genes within HEPHAESTUS responsible for individual metal tolerances include those encoding a P-type ATPase transporter-PcaA-required for cadmium and lead tolerance, a transporter-ZrcA-providing tolerance to zinc, and a multicopper oxidase-McoA-conferring tolerance to copper. In addition, a subregion of Hφ confers tolerance to arsenate. The genome sequences of other fungi in the Eurotiales contain further examples of HEPHAESTUS, suggesting that it is responsible for independently assembling tolerance to a diverse array of ions, including chromium, mercury, and sodium.


Assuntos
Cádmio , Elementos de DNA Transponíveis , Byssochlamys , Cádmio/toxicidade , Cobre/toxicidade , Elementos de DNA Transponíveis/genética , Zinco
4.
Plant Dis ; 106(1): 121-126, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34445878

RESUMO

Paecilomyces rot of apples is a postharvest disease caused by Paecilomyces niveus, a problematic spoiling agent of fruit juices and derivatives. Processing fruits infected with Paecilomyces rot can lead to juices contaminated with P. niveus ascospores. These ascospores are heat resistant and may survive food processing and germinate in finished products. Because the fungus produces the mycotoxin patulin, juice spoilage by P. niveus is an important health hazard. Little is known about the disease biology and control mechanisms of this recently described postharvest disease. The range of fruit products contaminated by P. niveus and patulin led us to hypothesize that the host range of Paecilomyces rot is broader than previously thought. Following Koch's postulates, we determined that multiple untested rosaceous fruits and popular apple cultivars are susceptible to Paecilomyces rot infection and that these infected fruits contain significant levels of patulin. We also observed that two closely related food spoiling fungi, Paecilomyces fulvus and Paecilomyces variotti, were unable to infect, cause symptoms in, or grow in wounded fruits. Therefore, we challenge the assumption that P. niveus spoilage inoculum is introduced to foods solely through environmental sources, and we show that other economically important rosaceous fruits, peaches, pears, sweet cherries, and sour cherries, are susceptible to infection and can also be sources of spoilage inoculum. Our results highlight the unique abilities of P. niveus to infect a variety of fruits, produce patulin, and form resistant spores capable of spoiling normally shelf-stable products.


Assuntos
Malus , Patulina , Pyrus , Byssochlamys , Frutas/química , Patulina/análise
5.
Food Sci Technol Int ; 28(3): 247-256, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33853398

RESUMO

The effect of ultrasound treatment (100 W, 30 kHz; 50 and 100% amplitudes) on inactivation of Saccharomyces cerevisiae and Byssochlamys fulva in pomegranate juice and shelf life of the juice during storage at different temperatures (5, 15 and 30 °C) for 30 days was modeled using predictive and thermodynamics models. The Baranyi and square root type models were implemented to determine the growth rate of microorganisms. It was predicted that the minimum growth temperature (Tmin) of B. fulva increased by increasing sonication amplitude, however, the Tmin of S. cerevisiae was not function of sonication amplitude. The predicted shelf life was shown to be in good agreement with the measured sensorial shelf life. Increasing the temperature from 5 to 35 °C, reduced the shelf life from 17.5 to 3.5 days for B. fulva and from 15 to 5 days for S. cerevisiae. Moreover, for B. fulva, the activation energy (Ea) decreased from 43.4 to 27.5 kJ/mol by increasing the amplitude, while no significant change was observed for S. cerevisiae. Besides, thermodynamics properties of the shelf life such as enthalpy (ΔH++), entropy (ΔS++) and Gibbs free energy (ΔG++)  were proven to be suitable measures to determine the microbial spoilage reaction.


Assuntos
Romã (Fruta) , Saccharomyces cerevisiae , Byssochlamys , Sonicação , Temperatura , Termodinâmica
6.
J Sci Food Agric ; 102(5): 1883-1893, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-34498275

RESUMO

BACKGROUND: The high cost of controlled-release urea (CRU) has prompted this study to explore whether the amount of CRU can be reduced by adding biostimulants while maintaining or increasing rice yield. A 2 year field experiment was conducted with CRU at three levels (60%, 80%, and 100% of the recommended nitrogen (N) fertilizer) and a novel biostimulant Paecilomyces variotii extract (ZNC), to investigate their synergistic effects on yield, nitrogen use efficiency (NUE), and net profitability of rice. RESULTS: Controlled-release urea achieved a significantly higher gain yield and NUE than conventional urea with the same N level, which could be attributed to its N supply. Even if the N level of CRU was reduced by 40%, both rice yield and net profit were still significantly higher than for the full amount of urea. Paecilomyces variotii extract sprayed on the surface of CRU at a dose of only 87.5 mL ha-1 exhibited ultra-high effectiveness by increasing the panicles, the N accumulation, and the rice yield. Controlled-release urea enriched by ZNC achieved significantly higher gain yield than CRU alone, increasing the yield by 9.2% and 8.7%, respectively, in 2 years under the full recommended N rate. The combination of 80% CRU and ZNC showed no significant difference in rice yield from treatment with 100% CRU, indicating that the rate of CRU could be reduced by ZNC. The application of ZNC further increased NUE, N partial factor productivity, and net profit. CONCLUSION: The CRU and ZNC combination provided a feasible approach for reducing N input while maintaining rice yield and agricultural sustainability. © 2021 Society of Chemical Industry.


Assuntos
Oryza , Agricultura , Byssochlamys , Preparações de Ação Retardada , Fertilizantes/análise , Nitrogênio/análise , Extratos Vegetais , Solo , Ureia
8.
Sci Rep ; 11(1): 16468, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34389757

RESUMO

Paecilomyces variotii xylanase was, produced in stirred tank bioreactor with yield of 760 U/mL and purified using 70% ammonium sulfate precipitation and ultra-filtration causing 3.29-fold purification with 34.47% activity recovery. The enzyme purity was analyzed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) confirming its monomeric nature as single band at 32 KDa. Zymography showed xylan hydrolysis activity at the same band. The purified enzyme had optimum activity at 60 °C and pH 5.0. The pH stability range was 5-9 and the temperature stability was up 70 °C. Fe2+and Fe3+ exhibited inhibition of xylanase enzyme while Cu2+, Ca2+, Mg2+ and Mn2+ stimulated its activity. Mercaptoethanol stimulated its activity; however, Na2-EDTA and SDS inhibited its activity. The purified xylanase could hydrolyze beechwood xylan but not carboxymethyl cellulose (CMC), avicel or soluble starch. Paecilomyces variotii xylanase Km and Vmax for beechwood were determined to be 3.33 mg/mL and 5555 U/mg, respectively. The produced xylanase enzyme applied on beech xylan resulted in different types of XOS. The antioxidant activity of xylo-oligosaccharides increased from 15.22 to 70.57% when the extract concentration was increased from 0.1 to 1.5 mg/mL. The enzyme characteristics and kinetic parameters indicated its high efficiency in the hydrolysis of xylan and its potential effectiveness in lignocellulosic hydrolysis and other industrial application. It also suggests the potential of xylanase enzyme for production of XOS from biomass which are useful in food and pharmaceutical industries.


Assuntos
Antioxidantes/metabolismo , Byssochlamys/metabolismo , Endo-1,4-beta-Xilanases/metabolismo , Glucuronatos/metabolismo , Oligossacarídeos/metabolismo , Reatores Biológicos , Byssochlamys/enzimologia , Eletroforese em Gel de Poliacrilamida , Endo-1,4-beta-Xilanases/isolamento & purificação , Concentração de Íons de Hidrogênio
9.
Biotechnol Bioeng ; 118(10): 4105-4118, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34255378

RESUMO

Corn dry milling provides a mature model for lignocellulose biorefinery process. To copy this technical success, a crucial step is to transform lignocellulose into starch-like carbohydrates (SLC), similar to milled corn grain and in a similar fashion to corn dry milling. The transformation process should be zero wastewater generation and sufficient fermentable sugar conservation; the product should be in solid particle form, free of toxic residues, and high enzymatic hydrolysis yield and fermentability. Here we designed and verified a SLC transformation process by (i) biodegradable oxalic acid-catalyzed pretreatment, and (ii) simultaneous biodegradation of inhibitors and oxalic acid catalyst. The oxalic acid catalyst was effective on disrupting the lignocellulose structure and also biodegradable at low pH value. The biodetoxification fungus Paecilomyces variotii FN89 was capable of degrading the furan/phenolic aldehydes and oxalic acid simultaneously and ultimately, while the fermentable sugars were well preserved. The obtained SLC from wheat straw and corn stover were similar to dry milled corn meal in terms of morphological properties, fermentable sugar contents, enzymatic hydrolysis yield, elemental contents, and free of inhibitors and acid catalyst. The bioconversion of starch-like wheat straw and corn stover produced 78.5 and 75.3 g/L of ethanol (9.9% and 9.5%, v/v) with the yield of 0.47 and 0.45 g ethanol/g cellulose/xylose, respectively, compared with 78.7 g/L (10.0%, v/v) from corn meal and the yield of 0.48 g ethanol/g starch. Mass balances suggest that the ethanol yield, wastewater generation, and elemental recycling of the SLC from lignocellulose were essentially the same as those of corn meal.


Assuntos
Ascomicetos/crescimento & desenvolvimento , Byssochlamys/crescimento & desenvolvimento , Celulase/química , Lignina/química , Amido/química , Triticum/química , Zea mays/química , Catálise , Hidrólise
10.
Fungal Genet Biol ; 152: 103567, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33989788

RESUMO

Fungi produce secondary metabolites that are not directly involved in their growth, but often contribute to their adaptation to extreme environmental stimuli and enable their survival. Conidial pigment or melanin is one of the secondary metabolites produced naturally by a polyketide synthesis (PKS) gene cluster in several filamentous fungi and is known to protect these fungi from extreme radiation conditions. Several pigmented or melanized fungi have been shown to grow under extreme radiation conditions at the Chernobyl nuclear accident site. Some of these fungi, including Paecilomyces variotii, were observed to grow towards the source of radiation. Therefore, in this study, we wanted to identify if the pigment produced by P. variotii, contributes to providing protection against radiation condition. We first identified the PKS gene responsible for synthesis of pigment in P. variotii and confirmed its role in providing protection against UV irradiation through CRISPR-Cas9 mediated gene deletion. This is the first report that describes the use of CRISPR methodology to create gene deletions in P. variotii. Further, we showed that the pigment produced by this fungus, was not inhibited by DHN-melanin pathway inhibitors, indicating that the fungus does not produce melanin. We then identified the pigment synthesized by the PKS gene of P. variotii, as a naptho-pyrone Ywa1, by heterologously expressing the gene in Aspergillus nidulans. The results obtained will further aid in understanding the mechanistic basis of radiation resistance.


Assuntos
Paecilomyces/genética , Paecilomyces/metabolismo , Paecilomyces/efeitos da radiação , Pigmentos Biológicos/biossíntese , Pigmentos Biológicos/genética , Pigmentos Biológicos/isolamento & purificação , Raios Ultravioleta , Aspergillus nidulans/genética , Byssochlamys , Acidente Nuclear de Chernobyl , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Melaninas/genética , Melaninas/isolamento & purificação , Redes e Vias Metabólicas , Testes de Sensibilidade Microbiana , Família Multigênica , Paecilomyces/isolamento & purificação , Pigmentação , Pigmentos Biológicos/metabolismo , Policetídeo Sintases/genética , Pironas/metabolismo , Metabolismo Secundário , Esporos Fúngicos/genética , Esporos Fúngicos/metabolismo
11.
Australas J Dermatol ; 62(3): e397-e399, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33759175

RESUMO

Mycetoma is a progressively mutilating infectious disease of the subcutaneous tissue that affects the skin and deep structures, which is poorly responsive to chemotherapy. Here, we report a skin mycetoma caused by Paecilomyces variotii, an uncommon fungus of human infections, and the therapeutic approach that resulted in a complete cure of the patient.


Assuntos
Antifúngicos/uso terapêutico , Byssochlamys , Itraconazol/uso terapêutico , Micetoma/tratamento farmacológico , Terbinafina/uso terapêutico , Administração Cutânea , Humanos , Resultado do Tratamento
12.
Nat Prod Res ; 35(22): 4448-4453, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32091239

RESUMO

One new chromone, lawsozaheer (1), and five known compounds 4-(2-hydroxyethyl) phenol (2), viriditoxin (3), stigmasta-4,6,8(14),22-tetraen-3-one (4), ß-sitosterol (5) and stigmasterol (6) were isolated from the fungal broth of Paecilomyces variotii. Their structures were elucidated using spectroscopic data. The configuration of 1 was determined by Horeau's method. The broth extract and compound 1 showed highly selective activity against Staphylococcus aureus (NCTC 6571) bacterium with 83.19 and 84.26% inhibition respectively at 150 µg/mL, comparing well with that of standard drug ofloxacin (87.013% inhibition at 100 µg/mL). Broth extract also showed 75, and 40% inhibition of Candida albicans and Fusarium lini, respectively.


Assuntos
Fusarium , Paecilomyces , Byssochlamys , Cromonas/farmacologia , Staphylococcus aureus
13.
J Antimicrob Chemother ; 76(3): 765-774, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33254240

RESUMO

OBJECTIVES: To provide a basis for clinical management decisions in Paecilomyces variotii infection. METHODS: Unpublished cases of invasive P. variotii infection from the FungiScope® registry and all cases reported in the literature were analysed. RESULTS: We identified 59 cases with P. variotii infection. Main baseline factors were presence of indwelling devices in 29 cases (49.2%), particularly peritoneal catheters (33.9%) and prosthetic heart valves (10.2%), haematological or oncological diseases in 19 (32.2%), major surgery in 11 (18.6%), and diabetes mellitus in 10 cases (16.9%). The most prevalent infection sites were peritoneum (n = 20, 33.3%) and lungs (n = 16, 27.1%). Pain and fever were frequent (n = 35, 59.3% and n = 33, 55.9%, respectively). Diagnosis was established by culture in 58 cases (98.3%). P. variotii caused breakthrough infection in 8 patients. Systemic antifungals were given in 52 patients (88.1%). Amphotericin B was administered in 39, itraconazole in 15, and posaconazole in 8 patients. Clinical isolates were frequently resistant to voriconazole, whereas the above-mentioned antifungals showed good in vitro activity. Infections of the blood and CNS caused high mortality. Overall mortality was 28.8% and death was attributed to P. variotii in 10 cases. CONCLUSIONS: P. variotii causes life-threatening infections, especially in immunocompromised and critically ill patients with indwelling devices. Patients undergoing peritoneal dialysis are at particular risk. Multidisciplinary management is paramount, including molecular techniques for diagnosis and treatment with efficacious systemic antifungals. Amphotericin B, itraconazole and posaconazole are regarded as treatments of choice. Combination with flucytosine may be considered. Surgical debridement and removal of indwelling devices facilitate favourable outcome.


Assuntos
Micoses , Paecilomyces , Antifúngicos/uso terapêutico , Byssochlamys , Humanos , Micoses/tratamento farmacológico , Micoses/epidemiologia , Sistema de Registros , Voriconazol
14.
Int J Food Microbiol ; 338: 108985, 2021 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-33334619

RESUMO

The management of Heat Resistant Moulds (HRMs) is considered a great challenge for the juice fruit industry. Neosartorya, Byssochlamys and Talaromyces are three out of the main genera isolated from fruit juices that show great resistance to heat treatments. Several inactivation parameters can be found in the literature, however all of them were carried out in specific food matrices and using diverse inactivation methods. Thus, this meta-analysis study synthesizes the thermal resistance parameters of the three HRMs by adjusting extended Bigelow-based meta-regression models to data on inactivation experiments conducted in different liquid media. The meta-analytical data, extracted from publications between 1969 and 2017, was composed of decimal reduction time (D), inactivation method, temperature of inactivation, pH, °Brix, age of spores, and type of medium (model, juice, concentrates). Pooled D* values (D at 90 °C, pH 3.5 and 12° Brix) were estimated for B. fulva (1.95 min; 95% CI: 1.21-3.11 min), Talaromyces (4.03 min; 95% CI: 3.43-4.74 min), Neosartorya (0.5.35 min; 95% CI: 4.10-7.08 min), and B. nivea (10.32 min; 95% CI: 5.81-18.4 min). It was found that increasing the soluble solids in concentrates tends to cause a lower decrease in the heat resistance of Neosartorya and Talaromyces than increasing the soluble solids in model liquid or juices (p = 0.001; 0.012). In general, the screw-capped tubes and three neck round inactivation methods render higher D* values (p < 0.05) than the thermal death tubes, the polyethylene bag and the capillary methods. Spores of Talaromyces (overall zpH = 7.56; 95% CI: 5.13-13.5) and Neosartorya (overall zpH = 7.07; 95% CI: 5.04-10.8) appear to be more thermal sensitive to a decrease in medium pH than spores of Byssochlamys (overall zpH = 4.34; 95% CI: 3.20-6.73). The meta-regression models presented in this study can be valuable for estimating pooled inactivation kinetic parameters to be used by the fruit juice industry in the management of thermal processes and in the determination of shelf-life.


Assuntos
Microbiologia de Alimentos , Fungos/fisiologia , Viabilidade Microbiana , Modelos Biológicos , Temperatura , Byssochlamys/fisiologia , Sucos de Frutas e Vegetais/microbiologia , Concentração de Íons de Hidrogênio , Neosartorya/fisiologia , Análise de Regressão , Esporos Fúngicos , Talaromyces/fisiologia
15.
Food Res Int ; 137: 109514, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33233149

RESUMO

Contamination by spores is often the cause of fungal food spoilage. Some distinct strains of the food spoilage fungus Paecilomyces variotii are able to produce airborne conidia that are more heat-resistant than similar species. These ellipsoid asexual spores can vary in size between strains, but also within strains. Here, we compared four measurement techniques to measure conidia size and distribution of five heat-sensitive and five heat-resistant P. variotii strains. Light microscopy (LM), Scanning Electron Microscopy (SEM) and Coulter Counter (CC) were used to measure and compare the spherical equivalent diameter, while CC and flow cytometry were used to study spore size distributions. The flow cytometry data was useful to study spore size distributions, but only relative spore sizes were obtained. There was no statistic difference between the method used of spore size measurement between LM, SEM and CC, but spore size was significantly different between strains with a 2.4-fold volume difference between the extremes. Various size distribution and shape parameters were correlated with conidial heat resistance. We found significant correlations in mean spore size, aspect ratio, roundness and skewness in relation to heat resistance, which suggests that these parameters are indicative for the conidial heat resistance of a P. variotii strain.


Assuntos
Temperatura Alta , Paecilomyces , Byssochlamys , Microbiologia de Alimentos , Esporos Fúngicos
16.
Int J Food Microbiol ; 333: 108773, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-32739634

RESUMO

The present work aimed to evaluate and to model the influence of UV-C light treatments with different irradiances (6.5, 13, 21, and 36 W/m2) on Aspergillus fischeri and Paecilomyces niveus ascospores inactivation in clarified apple juice. Approximately 5.0 and 6.0 log CFU/mL spores of P. niveus and A. fischeri, respectively, were suspended in 30 mL of clarified apple juice (pH 3.8, 12 ± 0.1°Brix) and exposed to UV-C light at different irradiances (as above) and exposure times (0 to 30 min). The first-order biphasic model was able to describe the experimental data with good statistical indices (RMSE = 0.296 and 0.308, R2 = 0.96 and 0.98, for P. niveus and A. fischeri respectively). At the highest irradiance level tested (36 W/m2), the UV-C light allowed the reduction of 5.7 and 4.2 log-cycles of A. fischeri and P. niveus ascospores, respectively, in approximately 10 min. P. niveus was the most UV-C resistant mould. The results showed that, to a defined UV-C fluence, a change in the level of either time or UV-C irradiance did not affect the effectiveness of UV-C light for A. fischeri and P. niveus inactivation. Thus, the modeling of the inactivation as a function of the UV-C fluence allowed the estimation of the primary model parameters with all experimental data and, consequently, no secondary models were needed. The model parameters were validated with experiments of variable UV-C fluences. Accordingly, experimental results allowed to conclude that UV-C treatment at the irradiances tested is a promising application for preventing A. fischeri and P. niveus spoilage of juices.


Assuntos
Aspergillus/efeitos da radiação , Sucos de Frutas e Vegetais/microbiologia , Paecilomyces/efeitos da radiação , Esporos Fúngicos/efeitos da radiação , Raios Ultravioleta , Byssochlamys/classificação , Microbiologia de Alimentos , Malus/microbiologia , Neosartorya/classificação
17.
Plant Dis ; 103(1): 125-131, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30444468

RESUMO

Paecilomyces rot of apples is a postharvest disease caused by the thermotolerant fungus Paecilomyces niveus (Byssochlamys nivea). The etiology of disease and the activity of fungicides against P. niveus are not yet well understood. This study evaluated the ability of P. niveus to infect 'Gala' apples growing in a conventionally managed orchard. In addition, the sensitivity of P. niveus isolates to postharvest fungicides difenoconazole, fludioxonil, and pyrimethanil was characterized for isolates from both agricultural and nonagricultural environments. Apples were wounded and mock-inoculated or inoculated with P. niveus in early July. At the time of harvest, 8 weeks after wounding, the inoculated apples had significantly larger lesions than mock-inoculated apples (P < 0.005). The average diameter of lesions on wound-inoculated apples was 11.17 mm ± 6.82 SD, while the average diameter of mock-inoculated lesions was 3.34 mm ± 1.85 SD. Disease symptoms in the orchard were similar to postharvest symptoms of Paecilomyces rot. Symptoms included a brown, flattened, circular lesion with faint concentric rings. The necrosis of mesocarp was firm and roughly U-shaped. Baseline isolates of P. niveus, from nonagricultural environments, were used to determine the effective fungicide dose at which growth was inhibited by 50% (EC50). Furthermore, fungicide sensitivity of P. niveus isolates was examined using relative growth assays at the mean baseline EC50 values to compare baseline isolates with isolates obtained from commercial apple orchards where they were likely exposed to fungicides. Among the exposed isolates, reduced sensitivity to all fungicides was observed, but significant differences between baseline and exposed isolates were only observed with fludioxonil (P < 0.0001). This is the first report demonstrating that P. niveus can infect apples that are wound-inoculated in the orchard and that isolates from agricultural environments are less sensitive to common fungicides, especially fludioxonil. This finding may have implications for the control of this postharvest diseases. Whether natural infections of apples by P. niveus is initiated in the orchard or during postharvest has yet to be determined.


Assuntos
Byssochlamys , Fungicidas Industriais , Malus , Paecilomyces , Virulência
18.
Prep Biochem Biotechnol ; 48(9): 777-786, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30303453

RESUMO

The objective of the present study was to optimize parameters for the cultivation of Lichtheimia corymbifera (mesophilic) and Byssochlamys spectabilis (thermophilic) for the production of ß-glucosidases and to compare the catalytic and thermodynamic properties of the partially purified enzymes. The maximum amount of ß-glucosidase produced by L. corymbifera was 39 U/g dry substrate (or 3.9 U/mL), and that by B. spectabilis was 77 U/g (or 7.7 U/mL). The optimum pH and temperature were 4.5 and 55 °C and 4.0 and 50 °C for the enzyme from L. corymbifera and B. spectabilis, respectively. ß-Glucosidase produced by L. corymbifera was stable at pH 4.0-7.5, whereas the enzyme from B. spectabilis was stable at pH 4.0-6.0. Regarding the thermostability, ß-glucosidase produced by B. spectabilis remained stable for 1 h at 50 °C, and that from L. corymbifera was active for 1 h at 45 °C. Determination of thermodynamic parameters confirmed the greater thermostability of the enzyme produced by the thermophilic fungus B. spectabilis, which showed higher values of ΔH, activation energy for denaturation (Ea), and half-life t(1/2). The enzymes were stable in the presence of ethanol and were competitively inhibited by glucose. These characteristics contribute to their use in the simultaneous saccharification and fermentation of vegetable biomass.


Assuntos
Byssochlamys/enzimologia , Celulases/química , Proteínas Fúngicas/química , Mucorales/enzimologia , Byssochlamys/crescimento & desenvolvimento , Catálise , Celulases/antagonistas & inibidores , Celulases/isolamento & purificação , Técnicas de Cultura/métodos , Inibidores Enzimáticos/química , Etanol/química , Proteínas Fúngicas/antagonistas & inibidores , Proteínas Fúngicas/isolamento & purificação , Glucose/química , Concentração de Íons de Hidrogênio , Cinética , Mucorales/crescimento & desenvolvimento , Temperatura , Termodinâmica
19.
Int J Food Microbiol ; 285: 27-33, 2018 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-30015260

RESUMO

Different fungi, including the genera Aspergillus (Neosartorya), Paecilomyces (Byssochlamys) and Talaromyces, produce (asco)spores that survive pasteurization treatments and are regarded as the most stress-resistant eukaryotic cells. The sensitivity of the ascospores to treatments with industrial sanitizers containing chlorine dioxide and iodine (iodophors) has never been assessed before. Ascospores of 4 species of Eurotiales were tested and showed clear variations in sensitivity. The most resilient species, T. macrosporus and Pae. variotii (=B. spectabilis) survive 75, but not 200 ppm chlorine dioxide solution treatments. These species were able to survive 75 ppm iodine solution treatments, but relatively low amounts of ascospores (100-1000 spores) could be inactivated after 16 h of treatment. Inactivated spores did not show any sign of germination after 7 days following treatment on growth medium. As judged by microscopy, iodine inactivation resulted in visibly distorted ascospores. For the interpretation of results, the state of dormancy or activation of ascospores is highly important.


Assuntos
Compostos Clorados/farmacologia , Eurotiales/efeitos dos fármacos , Microbiologia de Alimentos , Iodo/farmacologia , Óxidos/farmacologia , Esporos Fúngicos/efeitos dos fármacos , Aspergillus/efeitos dos fármacos , Byssochlamys/efeitos dos fármacos , Desinfetantes/farmacologia , Temperatura Alta , Neosartorya/efeitos dos fármacos , Talaromyces/crescimento & desenvolvimento
20.
Int J Food Microbiol ; 279: 80-87, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-29751279

RESUMO

The major aims of this study were to assess inter- and intra-species variability of heat resistant moulds (HRMs), Byssochlamys fulva and Byssochlamys nivea, with regards to (i) heat resistance and (ii) effect of heat treatment intensity on subsequent outgrowth. Four-week-old ascospores were suspended in buffered glucose solution (13° Brix, pH 3.5) and heat treated in a thermal cycler adjusted at 85 °C, 90 °C and 93 °C. Two variants of the Weibull model were fitted to the survival data and the following inactivation parameters estimated: b (inactivation rate, min-1), n (curve shape) and δ (the time taken for first decimal reduction, min). In addition to the assessment of heat resistance, outgrowth of Byssochlamys sp. from ascospores heated at 70 °C, 75 °C, 80 °C, 85 °C and 90 °C for 10 min and at 93 °C for 30 and 70 s was determined at 22 °C for up to 30 days. The Baranyi and Roberts model was fitted to the growth data to estimate the radial growth rates (µmax, mm.day-1) and lag times (λ, days). Inter-species variability and significant differences (p < 0.05) were observed for both inactivation and growth estimated parameters among B. fulva and B. nivea strains. The effect of heat treatment intensity on outgrowth of B. fulva strains was more apparent at the most intense heat treatment evaluated (90 °C/10 min), which was also the condition in which greater dispersion of the estimated kinetic parameters was observed. On the other hand, B. nivea strains were more affected by heating, resulting in greater variability of growth parameters estimated at different heating intensities and in very long lag phases (up to 25 days). The results show that inter- and intra-species variability in the kinetic parameters of Byssochlamys sp. needs to be taken into account for more accurate spoilage prediction. Furthermore, the effect of thermal treatments on subsequent outgrowth from ascospores should be explored in combination with other relevant factors such as °Brix and oxygen to develop thermal processes and storage conditions which can prevent the growth of HRMs and spoilage of heat treated food products.


Assuntos
Byssochlamys/crescimento & desenvolvimento , Temperatura Alta , Esporos Fúngicos/crescimento & desenvolvimento
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