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1.
Molecules ; 26(16)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34443346

RESUMO

A temperature dependence of saturated vapor pressure of isavuconazole (IVZ), an antimycotic drug, was found by using the method of inert gas-carrier transfer and the thermodynamic functions of sublimation were calculated at a temperature of 298.15 K. The value of the compound standard molar enthalpy of sublimation was found to be 138.1 ± 0.5 kJ·mol-1. The IVZ thermophysical properties-melting point and enthalpy-equaled 302.7 K and 29.9 kJ mol-1, respectively. The isothermal saturation method was used to determine the drug solubility in seven pharmaceutically relevant solvents within the temperature range from 293.15 to 313.15 K. The IVZ solubility in the studied solvents increased in the following order: buffer pH 7.4, buffer pH 2.0, buffer pH 1.2, hexane, 1-octanol, 1-propanol, ethanol. Depending on the solvent chemical nature, the compound solubility varied from 6.7 × 10-6 to 0.3 mol·L-1. The Hansen s approach was used for evaluating and analyzing the solubility data of drug. The results show that this model well-described intermolecular interactions in the solutions studied. It was established that in comparison with the van't Hoff model, the modified Apelblat one ensured the best correlation with the experimental solubility data of the studied drug. The activity coefficients at infinite dilution and dissolution excess thermodynamic functions of IVZ were calculated in each of the solvents. Temperature dependences of the compound partition coefficients were obtained in a binary 1-octanol/buffer pH 7.4 system and the transfer thermodynamic functions were calculated. The drug distribution from the aqueous solution to the organic medium was found to be spontaneous and entropy-driven.


Assuntos
Nitrilas/química , Piridinas/química , Temperatura , Triazóis/química , 1-Octanol/química , Varredura Diferencial de Calorimetria , Cristalização , Solubilidade , Solventes/química , Volatilização , Água/química
2.
Molecules ; 26(11)2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-34073527

RESUMO

This article studies the solubility, Hansen solubility parameters (HSPs), and thermodynamic behavior of a naturally-derived bioactive thymoquinone (TQ) in different binary combinations of isopropanol (IPA) and water (H2O). The mole fraction solubilities (x3) of TQ in various (IPA + H2O) compositions are measured at 298.2-318.2 K and 0.1 MPa. The HSPs of TQ, neat IPA, neat H2O, and binary (IPA + H2O) compositions free of TQ are also determined. The x3 data of TQ are regressed by van't Hoff, Apelblat, Yalkowsky-Roseman, Buchowski-Ksiazczak λh, Jouyban-Acree, and Jouyban-Acree-van't Hoff models. The maximum and minimum x3 values of TQ are recorded in neat IPA (7.63 × 10-2 at 318.2 K) and neat H2O (8.25 × 10-5 at 298.2 K), respectively. The solubility of TQ is recorded as increasing with the rise in temperature and IPA mass fraction in all (IPA + H2O) mixtures, including pure IPA and pure H2O. The HSP of TQ is similar to that of pure IPA, suggesting the great potential of IPA in TQ solubilization. The maximum molecular solute-solvent interactions are found in TQ-IPA compared to TQ-H2O. A thermodynamic study indicates an endothermic and entropy-driven dissolution of TQ in all (IPA + H2O) mixtures, including pure IPA and pure H2O.


Assuntos
2-Propanol/química , Benzoquinonas/química , Química Farmacêutica/métodos , Água/química , Técnicas de Química Analítica , Desenho de Fármacos , Análise de Regressão , Reprodutibilidade dos Testes , Solubilidade , Solventes , Temperatura , Termodinâmica
3.
Nat Prod Res ; 35(16): 2640-2646, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31441669

RESUMO

Protease (PPL) was isolated from Pseuderanthemum latifolium B. Hansen and had a molecular mass of 70 kDa. The N-terminal sequence of PPL showed 70-80% similarity with of subtilisin-like serine proteases from plants, but it did not show any sequence homology with known plant proteases. Serine protease inhibitors (PMSF, DFP) effectively blocked about 90% of PPL activity. PPL was highly activity at the pH range from 6 to 9 and temperatures from 50 °C to 80 °C, with an optimum at pH 7.0 and temperatures 70 °C. PPL had stability in a variety of pH, temperature, surfactant and oxidizing agents. PPL with concentration of 2.5 µg completely hydrolyzed the Aα-chain of fibrinogen within 5 min and hydrolyzed the Bß and the γ-chain after 10 h. Fibrin also was strong hydrolyzed by PPL with concentration of 0.3 µg. Thus, PPL is a unique serine protease, which it had strong fibrino(geno)lytic activities.


Assuntos
Acanthaceae/enzimologia , Serina Proteases/química , Sequência de Aminoácidos , Estabilidade Enzimática , Fibrina , Fibrinogênio , Concentração de Íons de Hidrogênio , Temperatura
4.
Yeast ; 38(5): 302-315, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33305394

RESUMO

Debaryomyces hansenii is traditionally described as a halotolerant non-conventional yeast and has served as a model organism for the study of osmotolerance and salt tolerance mechanisms in eukaryotic systems for the past 30 years. However, unraveling of D. hansenii's biotechnological potential has always been difficult due to the persistent limitations in the availability of efficient molecular tools described for this yeast. Additionally, there is a lack of consensus and contradictory information along the recent years that limits a comprehensive understanding of its central carbon metabolism, mainly due to a lack of physiological studies in controlled and monitored environments. Moreover, there is little consistency in the culture conditions (media composition, temperature, and pH among others) used by different groups, which makes it complicated when trying to get prevalent conclusions on behavioral patterns. In this work, we present for the first time a characterization of D. hansenii in batch cultivations using highly controlled lab-scale bioreactors. Our findings contribute to a more complete picture of the central carbon metabolism and the external pH influence on the yeast's ability to tolerate high Na+ and K+ concentrations, pointing to a differential effect of both salts, as well as a positive effect in cell performance when low environmental pH values are combined with a high sodium concentration in the media. Finally, a novel survival strategy at very high salinity (2 M) is proposed for this yeast, as well as potential outcomes for its use in industrial biotechnology applications. TAKE AWAY: High salt concentrations stimulate respiration in Debaryomyces hansenii. Sodium exerts a stronger positive impact on cell performance than potassium. µmax is higher at a combination of low pH, high salt, and high temperature. Concentrations of 2 M salt result in slower growth but increased biomass yield. The positive effect of salts is enhanced at low glucose concentration.


Assuntos
Reatores Biológicos , Carbono/metabolismo , Debaryomyces/metabolismo , Potássio/metabolismo , Salinidade , Sódio/metabolismo , Fermentação , Concentração de Íons de Hidrogênio , Temperatura
5.
Am J Bot ; 107(11): 1491-1503, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33190268

RESUMO

PREMISE: Leaf phenology is an essential developmental process in trees and an important component in understanding climate change. However, little is known about the regulation of leaf phenology in tropical trees. METHODS: To understand the regulation by temperature of leaf phenology in tropical trees, we performed daily observations of leaf production under rainfall-independent conditions using saplings of Shorea leprosula and Neobalanocarpus heimii, both species of Dipterocarpaceae, a dominant tree family of Southeast Asia. We analyzed the time-series data obtained using empirical dynamic modeling (EDM) and conducted growth chamber experiments. RESULTS: Leaf production by dipterocarps fluctuated in the absence of fluctuation in rainfall, and the peaks of leaf production were more frequent than those of day length, suggesting that leaf production cannot be fully explained by these environmental factors, although they have been proposed as regulators of leaf phenology in dipterocarps. Instead, EDM suggested a causal relationship between temperature and leaf production in dipterocarps. Leaf production by N. heimii saplings in chambers significantly increased when temperature was increased after long-term low-temperature treatment. This increase in leaf production was observed even when only nighttime temperature was elevated, suggesting that the effect of temperature on development is not mediated by photosynthesis. CONCLUSIONS: Because seasonal variation in temperature in the tropics is small, effects on leaf phenology have been overlooked. However, our results suggest that temperature is a regulator of leaf phenology in dipterocarps. This information will contribute to better understanding of the effects of climate change in the tropics.


Assuntos
Dipterocarpaceae , Ásia Sudeste , Folhas de Planta , Estações do Ano , Temperatura , Árvores
6.
Curr Microbiol ; 77(11): 3377-3384, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32936341

RESUMO

Yeasts play an important role in cheese making, by contributing to microbial community establishment and improving flavor. This study aimed at investigating the impact of NaCl and temperature on growth and survival of 20 strains belonging to the yeast species Candida intermedia (2 strains), Debaryomyces hansenii (11), Kluyveromyces lactis (1), Papiliotrema flavescens (1), Rhodotorula glutinis (1), Sterigmatomyces halophilus (2) and Yamadazyma triangularis (2) isolated from Danish cheese brines. All yeasts could grow in Malt Yeast Glucose Peptone (MYGP) medium with low NaCl (≤ 4%, w/v) concentrations at 25 °C and 16 °C. Further, none of the strains, except for one strain of D. hansenii (KU-9), were able to grow under a condition mimicking cheese brine (MYGP with 23% (w/v) NaCl and 6.3 g/L lactate) at 25 °C, while all yeasts could grow at 16 °C, except for the two strains of C. intermedia. In the survival experiment, D. hansenii, S. halophilus and Y. triangularis survived in MYGP with 23% (w/v) NaCl throughout 13.5 days at 25 °C, with Y. triangularis and S. halophilus being the most NaCl tolerant, while the remaining yeasts survived for less than 7 days. These results enable the selection of relevant yeasts from cheese brines for potential use in the cheese industry.


Assuntos
Queijo , Basidiomycota , Contagem de Colônia Microbiana , Dinamarca , Microbiologia de Alimentos , Kluyveromyces , Rhodotorula , Saccharomycetales , Sais , Cloreto de Sódio , Temperatura , Leveduras
7.
Food Chem ; 317: 126465, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32114276

RESUMO

Based on the experimental data of gas chromatography-mass spectrometry, an improved artificial neural network was first established to predict the migration of 2-ethylhexyl phthalate (DEHP) plasticizer from poly(vinylidene chloride) (PVDC) into food simulants (ie., heptane, ethanol and water). The sensitivity analysis indicated that temperature acted as a crucial factor influencing the migration values of DEHP. Then, a combined experimental and molecular dynamic (MD) simulation was performed to understand the migration kinetics and the mechanism of DEHP. Hansen solubility parameters of three component (δd, δp, δh) were simplified into two-component solubility parameters (δvdW, δe), and the tuple was successfully applied to describe the interactions between PVDC and food simulants. The MD results showed that high interaction energy and fractional free volume in PVDC/DEHP/food simulant systems accelerated the migration of DEHP. These fundamental studies would provide significant insights into the migration of environmental contaminants.


Assuntos
Dietilexilftalato/análise , Embalagem de Alimentos , Redes Neurais de Computação , Plastificantes/análise , Dietilexilftalato/química , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas , Simulação de Dinâmica Molecular , Plastificantes/química , Cloreto de Polivinila/análogos & derivados , Cloreto de Polivinila/química , Solubilidade , Temperatura
8.
Microbiology (Reading) ; 166(5): 474-483, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32100712

RESUMO

Mycobacterium hassiacum is so far the most thermophilic among mycobacteria as it grows optimally at 50 °C and up to 65 °C in a glycerol-based medium, as verified in this study. Since this and other nontuberculous mycobacteria (NTM) thrive in diverse natural and artificial environments, from where they may access and infect humans, we deemed essential to probe M. hassiacum resistance to heat, a strategy routinely used to control microbial growth in water-supply systems, as well as in the food and drink industries. In addition to possibly being a threat in its own right in rare occasions, M. hassiacum is also a good surrogate for studying other NTM species more often associated with opportunistic infection, namely Mycobacterium avium and Mycobacterium abscessus as well as their strictly pathogenic counterparts Mycobacterium tuberculosis and Mycobacterium leprae. In this regard, this thermophilic species is likely to be useful as a source of stable proteins that may provide more detailed structures of potential drug targets. Here, we investigate M. hassiacum growth at near-pasteurization temperatures and at different pHs and also characterize its thermostable glucosyl-3-phosphoglycerate synthase (GpgS), an enzyme considered essential for M. tuberculosis growth and associated with both nitrogen starvation and thermal stress in different NTM species.


Assuntos
Proteínas de Bactérias/metabolismo , Glucosiltransferases/metabolismo , Mycobacteriaceae/crescimento & desenvolvimento , Mycobacteriaceae/genética , Proteínas de Bactérias/genética , DNA Bacteriano/genética , Glucosiltransferases/genética , Concentração de Íons de Hidrogênio , Mycobacteriaceae/metabolismo , Micobactérias não Tuberculosas/genética , Micobactérias não Tuberculosas/crescimento & desenvolvimento , Micobactérias não Tuberculosas/metabolismo , Pasteurização , Temperatura
9.
Int J Biol Macromol ; 144: 198-207, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31843613

RESUMO

Optimization of the culture parameters used for biocellulose (BC) production by a previously isolated bacterial strain (Komagataeibacter hansenii AS.5) was carried out. The effect of nine culture parameters on BC production was evaluated by implementing the Plackett-Burman design, and the results revealed that, the most significant variables affecting BC production were MgSO4, ethanol, pH and yeast extract. A three-level and four-factor Box-Behnken design was applied to determine the optimum level of each significant variable. According to the results of the Plackett-Burman (PBD) and Box-Behnken designs (BBD), the following medium composition and parameters were calculated to be optimum (g/l): glucose 25, yeast extract 13, MgSO4 0.15, KH2PO4 2, ethanol 7.18 ml/l, pH 5.5, inoclume size 7%, cultivation temperature 20 °C and incubation time 9 days. Characterization of purified BC was performed to determine the network morphology by scanning electron microscopy, crystallinity by X-ray diffraction, chemical structure and functional groups by Fourier-transform infrared spectroscopy, thermal stability by thermogravimetric analysis and mechanical properties such as Young's modulus, tensile strength and elongation at beak % of BC.


Assuntos
Acetobacteraceae/metabolismo , Celulose/biossíntese , Celulose/isolamento & purificação , Celulose/ultraestrutura , Meios de Cultura , Glucose/metabolismo , Fenômenos Mecânicos , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Resistência à Tração , Termogravimetria , Difração de Raios X
10.
Int J Food Microbiol ; 313: 108390, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31678818

RESUMO

Growth of L. monocytogenes is among the most important factors affecting the risk of human listeriosis. In ready to eat leafy greens, the use of anti-Listeria treatments represents a good alternative to inhibit growth during storage. Several commercially available antimicrobial agents have been suggested as effective intervention strategies. Among them, phage preparations and bacteriocin-producing strains have shown promising results against L. monocytogenes. In this study, we investigate the efficacy of two commercially available surface treatments, the bacteriophage formulation PhageGuard Listex (Micreos Food Safety B.V., NL) and the bacteriocin-producing culture SafePro® (CHR Hansen, DK) to inactivate L. monocytogenes in fresh-cut curly endive after processing and during storage. Fresh-cut endive was inoculated with a cold-adapted L. monocytogenes cocktail of 6 strains (4.4 ±â€¯0.0 log cfu/g) and treated with the anti-Listeria treatments. The treatments were applied using a spray system at two different places within the processing line, on the conveyor belt and in the centrifuge. A total of 5 different treatments were applied: i) Untreated (CT); ii) PhageGuard Listex on the conveyor belt (Listex_Conveyor); iii) PhageGuard Listex during centrifugation (Listex_Centrifuge); iv) SafePro on the conveyor belt (SafePro_Conveyor); and v) SafePro during centrifugation (SafePro_Centrifuge). Samples were stored 3 days at 5 °C plus 5 days at 8 °C. PhageGuard Listex treatment reduced L. monocytogenes in fresh-cut endive by 2.5 logs, regardless of the place of treatment application (conveyor belt or centrifuge). On the other hand, SafePro only reduced L. monocytogenes by 0.2 and 0.4 logs, at the conveyor belt and centrifuge, respectively. Maximum L. monocytogenes reductions of about 3.5 log units were observed in fresh-cut endive treated with PhageGuard Listex after 3 days of storage. At the end of the shelf life (8 days), the initial trends were maintained and the fresh-cut curly endive treated with PhageGuard Listex showed the lowest L. monocytogenes concentration. However, by the end of the shelf-life, L. monocytogenes showed higher levels (1.3-fold) than immediately after the application of the treatment. One hypothesis could be that L. monocytogenes cells, which were able to survive the anti-Listeria treatments, were also able to proliferate under the specific storage conditions. Based on the obtained results, PhageGuard Listex seems to be a promising decontamination agent for leafy greens aiming to reduce growth of the bacteria but further work is needed.


Assuntos
Conservação de Alimentos/métodos , Listeria monocytogenes/crescimento & desenvolvimento , Verduras/microbiologia , Bacteriocinas/metabolismo , Bacteriófagos/fisiologia , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Conservação de Alimentos/instrumentação , Inocuidade dos Alimentos , Humanos , Listeria monocytogenes/metabolismo , Listeria monocytogenes/virologia , Projetos Piloto , Folhas de Planta/microbiologia , Temperatura
11.
Harmful Algae ; 90: 101709, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31806165

RESUMO

Despite nearly annual blooms of the neurotoxic dinoflagellate Karenia brevis (Davis) G. Hansen and Moestrup in the Gulf of Mexico, defining the suite of biological traits that explain its proliferation has remained challenging. Studies have described K. brevis as a low-light-adapted species, incapable of sustaining growth under high light, which is at odds with observed surface aggregations sometimes within centimeters of the sea surface and also with short-term experiments showing photosynthetic machinery accommodating high irradiances. Here, growth and photophysiology of three K. brevis isolates were evaluated under a range of environmentally relevant irradiances (10-1500 µmol photons m-2 s-1) in the laboratory. No differences in growth-irradiance curves were observed among isolates; all sustained maximum growth rates at the highest irradiances examined, even in exposures as long as three weeks. The growth efficiency α of K. brevis under light-limiting conditions appeared mediocre among dinoflagellates, and poorer than that of other phytoplankton (e.g., diatoms, cyanobacteria), implying that K. brevis is not a low-light specialist. This finding substantially alters earlier parameterizations of K. brevis growth-irradiance curves. Therefore, a model was developed to contextualize how these new growth-irradiance curves might affect bottom growth rates. This model was subsequently applied to a case study comparing seasonal light forcing offshore of Pinellas County, FL, USA, with a single empirical value for light attenuation, and seasonal bottom water temperatures. Predictions suggested that light may limit bottom growth as close as 1 km from shore in winter, but would only begin limiting growth 20 km from shore in summer. Population maintenance (no net growth) was possible as far offshore as 90 km in summer and 68 km in winter. These ranges intercept areas thought to be important for bloom initiation.


Assuntos
Dinoflagelados , Florida , Golfo do México , Fitoplâncton , Temperatura
12.
Molecules ; 24(18)2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31527447

RESUMO

To successfully design and optimize the application of hydrogel matrices one has to effectively combine computational design tools with experimental methods. In this context, one of the most promising techniques is molecular modeling, which requires however accurate molecular models representing the investigated material. Although this method has been successfully used over the years for predicting the properties of polymers, its application to biopolymers, including gelatin, is limited. In this paper we provide a method for creating an atomistic representation of gelatin based on the modified FASTA codes of natural collagen. We show that the model created in this manner reproduces known experimental values of gelatin properties like density, glass-rubber transition temperature, WAXS profile and isobaric thermal expansion coefficient. We also present that molecular dynamics using the INTERFACE force field provides enough accuracy to track changes of density, fractional free volume and Hansen solubility coefficient over a narrow temperature regime (273-318 K) with 1 K accuracy. Thus we depict that using molecular dynamics one can predict properties of gelatin biopolymer as an efficient matrix for immobilization of various bioactive compounds, including enzymes.


Assuntos
Gelatina/química , Modelos Moleculares , Conformação Proteica , Algoritmos , Sequência de Aminoácidos , Análise de Variância , Biopolímeros/química , Hidrogéis/química , Temperatura
13.
AAPS PharmSciTech ; 20(5): 204, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31140011

RESUMO

Deep eutectic solvents (DESs) have recently been getting a great deal of attention in many fields of science and technology. The objective of this study was to peruse the solubility of indomethacin (IMC) as sparingly soluble drug in some tetrabutylammonium bromide (TBAB)-based DESs (TBAB/ethylene glycol and TBAB/glycerol). The shake flask method has been employed in this study at temperature ranges T = (298.15-313.15) K and atmospheric pressure (pP = 86.6 kPa). The results showed that the solubility of IMC in TBAB/ethylene glycol system was obtained approximately 17,000-fold more than its solubility in water. The solubility data were accurately correlated by the famous local composition activity coefficient models including e-NRTL and UNIQUAC. It was also our aim to evaluate Hansen solubility parameters in IMC solubility prediction. These parameters can help to predict the solvent performance during the manufacturing processes and will be useful in guessing solvent behavior in many other fields of effort. The experimental and the Hansen solubility parameters results are very well matched. In addition, the apparent thermodynamic properties of dissolution and mixing were studied in these solutions based on Van't Hoff and Gibbs equations.


Assuntos
Anti-Inflamatórios não Esteroides/química , Indometacina/química , Modelos Químicos , Compostos de Amônio Quaternário/química , Temperatura , Água/química , Anti-Inflamatórios não Esteroides/farmacocinética , Previsões , Indometacina/farmacocinética , Compostos de Amônio Quaternário/farmacocinética , Solubilidade , Solventes , Termodinâmica
14.
Drug Dev Ind Pharm ; 45(8): 1258-1264, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30995878

RESUMO

Gemfibrozil (GEM) is cholesterol-lowering agent which is being proposed as poorly water soluble drug (PWSD). Temperature based solubility values of GEM are not yet available in literature or any pharmacopoeia/monograph. Hence, the present studies were carried out to determine the solubility of PWSD GEM (as mole fraction) in various pharmaceutically used solvents such as water (H2O), methanol (MeOH), ethanol (EtOH), isopropanol (IPA), 1-butanol (1-BuOH), 2-butanol (2-BuOH), ethylene glycol (EG), propylene glycol (PG), polyethylene glycol-400 (PEG-400), ethyl acetate (EA), dimethyl sulfoxide (DMSO) and Transcutol® (THP) at the temperatures ranging from T = 298.2 K-318.2 K under atmospheric pressure P = 0.1 MPa. Equilibrium/experimental solubilities of GEM were recorded by applying a saturation shake flask methodology and regressed using 'van't Hoff and Apelblat models'. Hansen solubility parameters for GEM and various pharmaceutically used solvents were estimated using HSPiP software. The solid states of GEM (both in pure and equilibrated states) were studied by 'Differential Scanning Calorimetry' which confirmed no transformation of GEM after equilibrium. Experimental solubilities of GEM in mole fraction were observed maximum in THP (1.81 × 10-1) followed by DMSO, PEG-400, EA, 1-BuOH, 2-BuOH, IPA, EtOH, PG, MeOH, EG and H2O (3.24 × 10-6) at T = 318.2 K and similar tendencies were also recorded at T = 298.2 K, T = 303.2 K, T = 308.2 K and T = 313.2 K. 'Apparent thermodynamic analysis' on experimental solubilities furnished 'endothermic and entropy-driven dissolution' of GEM in each pharmaceutically used solvent.


Assuntos
Genfibrozila/química , Solubilidade/efeitos dos fármacos , Solventes/química , 2-Propanol/química , Acetatos/química , Etilenoglicóis/química , Metanol/química , Polietilenoglicóis/química , Temperatura , Termodinâmica , Água/química
15.
Int J Biol Macromol ; 119: 1077-1082, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30031822

RESUMO

Nowadays, the biological control of various yeast and mold pathogens that cause diseases in humans, animals, and plants is an increasing of interest. The discovery of novel agents allows prevention of infectious diseases and post-harvest losses reported every year. In the study, we aimed to investigate the production, purification, and characterization as well as in vivo biocontrol efficiency of killer toxins produced by Debaryomyces hansenii strains TEM8 and TEM17. The molecular mass of the killer toxins was 31.5 kDa and they showed high stability at pHs between 2.5 and 5.5 and up to 37 °C. Their internal amino acid sequences matched the DEHA2G18766g (CAG90862.1) from D. hansenii CBS767, which is similar to Saccharomyces cerevisiae YGR282C BGL2 endo-beta-1,3-glucanase. The yeasts and their purified killer toxins significantly inhibited the growth of plant pathogenic fungi Alternaria brassicicola, Alternaria citri, Aspergillus niger and Rhizopus stolonifer in fruits. The findings of this paper have recommended these yeast strains and their toxins as effective biocontrol agents against fungi that cause post-harvest diseases.


Assuntos
Ascomicetos/química , Agentes de Controle Biológico/química , Agentes de Controle Biológico/farmacologia , Micotoxinas/química , Micotoxinas/farmacologia , Sequência de Aminoácidos , Agentes de Controle Biológico/isolamento & purificação , Ativação Enzimática , Concentração de Íons de Hidrogênio , Espectrometria de Massas , Micotoxinas/isolamento & purificação , Proteólise , Temperatura
16.
J Appl Microbiol ; 124(6): 1377-1392, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29464844

RESUMO

AIMS: The objective was to determine the effects of dietary substitution of fishmeal (FM) with live yeast and increasing water temperature on the diversity and composition of gut microbiota in rainbow trout. METHODS AND RESULTS: Fish were fed either FM or yeast (Saccharomyces cerevisiae) and reared in water temperatures of either 11°C (cold) or 18°C (warm) for 6 weeks. Luminal content and mucosa were collected from the distal gut and the load, diversity and species abundance of yeast and bacteria were analysed using agar plating, MALDI-TOF and rRNA gene amplicon sequencing. Yeast in the gut of fish fed FM were represented by S. cerevisiae, Rhodotorula spp. and Debaryomyces hansenii, while fish fed yeast contained 4-5 log higher CFU per g of yeast that were entirely represented by S. cerevisiae. For gut bacteria, sequencing of 16S rRNA gene amplicons using Illumina MiSeq showed lower bacterial diversity and abundance of lactic acid bacteria, especially Lactobacillus, in fish reared in warm rather than cold water. Fish fed yeast had similar bacterial diversity and lower abundance of Leuconostocaceae and Photobacterium compared with fish fed FM. CONCLUSIONS: Feeding live yeast mainly increased yeast load in the gut, while increased water temperature significantly altered the gut microbiota of rainbow trout in terms of bacterial diversity and abundance. SIGNIFICANCE AND IMPACT OF THE STUDY: Live yeast can replace 40% of FM without disrupting bacteria communities in the gut of rainbow trout, while increased water temperature due to seasonal fluctuations and/or climate change may result in a gut dysbiosis that may jeopardize the health of farmed fish.


Assuntos
Ração Animal/microbiologia , Bactérias/isolamento & purificação , Microbioma Gastrointestinal , Oncorhynchus mykiss/microbiologia , Saccharomyces cerevisiae/metabolismo , Ração Animal/análise , Animais , Bactérias/classificação , Bactérias/genética , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/microbiologia , Oncorhynchus mykiss/crescimento & desenvolvimento , Oncorhynchus mykiss/metabolismo , RNA Ribossômico 16S/genética , Saccharomyces cerevisiae/genética , Temperatura , Água/química
17.
J Microbiol Biotechnol ; 28(4): 579-587, 2018 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-29385667

RESUMO

For biotechnological production of high-valued ß-D-hexyl glucoside, the catalytic properties of Hanseniaspora thailandica BC9 ß-glucosidase purified from the periplasmic fraction were studied, and the transglycosylation activity for the production of ß-D-hexyl glucoside was optimized. The constitutive BC9 ß-glucosidase exhibited maximum specific activity at pH 6.0 and 40ºC, and the activity of BC9 ß-glucosidase was not significantly inhibited by various metal ions. BC9 ß-glucosidase did not show a significant activity of cellobiose hydrolysis, but the activity was rather enhanced in the presence of sucrose and medium-chain alcohols. BC9 ß-glucosidase exhibited enhanced production of ß-D-hexyl glucoside in the presence of DMSO, and 62% of ß-D-hexyl glucoside conversion was recorded in 4 h in the presence of 5% 1-hexanol and 15% DMSO.


Assuntos
Glucosídeos/biossíntese , Hanseniaspora/enzimologia , beta-Glucosidase/química , beta-Glucosidase/metabolismo , Álcoois/metabolismo , Catálise , Celobiose/metabolismo , Estabilidade Enzimática , Proteínas Fúngicas/química , Proteínas Fúngicas/isolamento & purificação , Proteínas Fúngicas/metabolismo , Glicosilação , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Metais/metabolismo , Solventes , Especificidade por Substrato , Sacarose/metabolismo , Açúcares/metabolismo , Temperatura , Fatores de Tempo , beta-Glucosidase/isolamento & purificação
18.
Food Chem ; 244: 266-274, 2018 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-29120781

RESUMO

Taguchi design was used to examine the effect of parameters that should be optimized in order to control the alcoholic fermentation of the concentrated grape must (CGM) from cv. Xinomavro using the best-performing indigenous Hanseniaspora uvarum and Saccharomyces cerevisiae strains as multistarters. The "optimum" combination of conditions (cell ratio of H. uvarum/S. cerevisiae; inoculum size and inoculation time of S. cerevisiae; fermentation time and temperature) resulted in an alcoholic product that meets ethanol (79 g/kg) and residual sugar (164 g/kg) content requirements for further use in the production of balsamic type vinegar. Multistarter fermentation affected positively the varietal organoleptic traits of the fermented CGM. 5-(Hydroxymethyl)-furfural content emerged as a critical factor for the standardization of this process. Scaling up experiments in 12 L barrels verified findings from small scale in 100 mL flasks. The results of this work can be used as a prototype in further similar efforts.


Assuntos
Ácido Acético/metabolismo , Biotecnologia/métodos , Etanol/metabolismo , Fermentação , Hanseniaspora/metabolismo , Saccharomyces cerevisiae/metabolismo , Grécia , Temperatura , Vitis/química
19.
J Microbiol Biotechnol ; 27(9): 1576-1585, 2017 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-28683529

RESUMO

Yeasts, filamentous fungi, and bacteria colonize the surface of fermented sausages during the ripening process. The source of this microbiota is their surrounding environment, and is influenced by the maturing conditions and starter cultures. Debaryomyces hansenii was previously isolated from several dry-cured meat products and associated with the lipolytic and proteolytic changes that occur in these products, influencing their taste and flavor. Therefore, this study isolated the yeast microbiota present in the casing from different meat products ("lomo," "chorizo," and "salchichón") from the Valle de los Pedroches region in southern Spain. D. hansenii was by far the most abundant species in each product, as all 22 selected isolates were identified as D. hansenii by biochemical and/or molecular methods. In contrast, no yeasts were found in the meat batter. These data constitute the first study of the yeasts present in "lomo" sausages and particularly the highly appreciated Valle de los Pedroches "lomo" sausages. Furthermore, the resistance of these isolates to different pHs, temperatures, and saline stress was studied, together with their catabolic characteristics. Based on the results, certain isolates are proposed as valuable candidate starter cultures that could improve both the manufacture and the flavor of such dry-cured meat products, and provide an understanding of new mechanisms involved in stress tolerance. Applied mediumscale industrial tests are currently in progress.


Assuntos
Produtos da Carne/microbiologia , Saccharomycetales , Animais , Contagem de Colônia Microbiana , Concentração de Íons de Hidrogênio , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Saccharomycetales/metabolismo , Saccharomycetales/fisiologia , Espanha , Temperatura
20.
Mol Ecol ; 26(19): 5074-5085, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28749031

RESUMO

Elucidating the physiological mechanisms of the irregular yet concerted flowering rhythm of mass flowering tree species in the tropics requires long-term monitoring of flowering phenology, exogenous and endogenous environmental factors, as well as identifying interactions and dependencies among these factors. To investigate the proximate factors for floral initiation of mast seeding trees in the tropics, we monitored the expression dynamics of two key flowering genes, meteorological conditions and endogenous resources over two flowering events of Shorea curtisii and Shorea leprosula in the Malay Peninsula. Comparisons of expression dynamics of genes studied indicated functional conservation of FLOWERING LOCUS T (FT) and LEAFY (LFY) in Shorea. The genes were highly expressed at least 1 month before anthesis for both species. A mathematical model considering the synergistic effect of cool temperature and drought on activation of the flowering gene was successful in predicting the observed gene expression patterns. Requirement of both cool temperature and drought for floral transition suggested by the model implies that flowering phenologies of these species are sensitive to climate change. Our molecular phenology approach in the tropics sheds light on the conserved role of flowering genes in plants inhabiting different climate zones and can be widely applied to dissect the flowering processes in other plant species.


Assuntos
Dipterocarpaceae/genética , Flores/fisiologia , Proteínas de Plantas/genética , Mudança Climática , Dipterocarpaceae/fisiologia , Secas , Flores/genética , Florestas , Regulação da Expressão Gênica de Plantas , Malásia , Modelos Teóricos , Temperatura , Fatores de Transcrição/genética
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