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1.
J Microbiol Biotechnol ; 31(3): 429-438, 2021 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-33323677

RESUMO

Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis.


Assuntos
Acetobacteraceae/metabolismo , Carbono/metabolismo , Celulose/biossíntese , Concentração de Íons de Hidrogênio , Celulose/química , Meios de Cultura , Gluconatos/metabolismo , Glicerol/metabolismo , Microscopia Eletrônica de Varredura , Difração de Raios X
2.
Curr Genet ; 66(6): 1135-1153, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32719935

RESUMO

Halotolerant species are adapted to dealing continually with hyperosmotic environments, having evolved strategies that are uncommon in other organisms. The HOG pathway is the master system that regulates the cellular adaptation under these conditions; nevertheless, apart from the importance of Debaryomyces hansenii as an organism representative of the halotolerant class, its HOG1 pathway has been poorly studied, due to the difficulty of applying conventional recombinant DNA technology. Here we describe for the first time the phenotypic characterisation of a null HOG1 mutant of D. hansenii. Dhhog1Δ strain was found moderately resistant to 1 M NaCl and sensitive to higher concentrations. Under hyperosmotic shock, DhHog1 fully upregulated transcription of DhSTL1 and partially upregulated that of DhGPD1. High osmotic stress lead to long-term inner glycerol accumulation that was partially dependent on DhHog1. These observations indicated that the HOG pathway is required for survival under high external osmolarity but dispensable under low and mid-osmotic conditions. It was also found that DhHog1 can regulate response to alkali stress during hyperosmotic conditions and that it plays a role in oxidative and endoplasmic reticulum stress. Taken together, these results provide new insight into the contribution of this MAPK in halotolerance of this yeast.


Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana Transportadoras/genética , Osmorregulação/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomycetales/genética , Álcalis/efeitos adversos , Regulação Fúngica da Expressão Gênica , Glicerol/metabolismo , Pressão Osmótica/fisiologia , Fosforilação , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomycetales/metabolismo , Saccharomycetales/fisiologia , Transdução de Sinais/genética
3.
Artigo em Inglês | MEDLINE | ID: mdl-29774204

RESUMO

Certain yeasts secrete peptides known as killer toxins or mycocins with a deleterious effect on sensitive yeasts or filamentous fungi, a common phenomenon in environmental species. In a recent work, different Debaryomyces hansenii (Dh) strains isolated from a wide variety of cheeses were identified as producing killer toxins active against Candida albicans and Candida tropicalis. We have analyzed the killer activity of these toxins in C. albicans mutants defective in MAPK signaling pathways and found that the lack of the MAPK Hog1 (but not Cek1 or Mkc1) renders cells hypersensitive to Dh mycocins while mutants lacking other upstream elements of the pathway behave as the wild type strain. Point mutations in the phosphorylation site (T174A-176F) or in the kinase domain (K52R) of HOG1 gene showed that both activities were relevant for the survival of C. albicans to Dh killer toxins. Moreover, Hog1 phosphorylation was also required to sense and adapt to osmotic and oxidative stress while the kinase activity was somehow dispensable. Although the addition of supernatant from the killer toxin- producing D. hansenii 242 strain (Dh-242) induced a slight intracellular increase in Reactive Oxygen Species (ROS), overexpression of cytosolic catalase did not protect C. albicans against this mycocin. This supernatant induced an increase in intracellular glycerol concentration suggesting that this toxin triggers an osmotic stress. We also provide evidence of a correlation between sensitivity to Dh-242 killer toxin and resistance to Congo red, suggesting cell wall specific alterations in sensitive strains.


Assuntos
Candida albicans/efeitos dos fármacos , Proteínas Fúngicas/metabolismo , Fatores Matadores de Levedura/farmacologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Candida albicans/enzimologia , Candida albicans/genética , Candida tropicalis/efeitos dos fármacos , Candida tropicalis/enzimologia , Candida tropicalis/genética , Catalase/metabolismo , Debaryomyces/genética , Debaryomyces/metabolismo , Proteínas Fúngicas/genética , Glicerol/metabolismo , Proteínas Quinases Ativadas por Mitógeno/genética , Mutação , Pressão Osmótica/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
4.
Fungal Genet Biol ; 100: 52-60, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28215981

RESUMO

Debaryomyces hansenii is a halotolerant and Na+-includer yeast that can be isolated from different food and low-water activity products. It has also been defined as a marine-occurring yeast but key aspects for this salt tolerant behavior are far from being understood. Here, we searched for clues helping to elucidate the basis of this ability. Our results on growth, Rb+ transport, total K+ and Na+ content and vacuolar fragmentation are compatible with a yeast species adapted to cope with salt stress. On the other hand, we confirmed the existence of D. hansenii strategies that are generally observed in sensitive organisms, such as the production of glycerol as a compatible solute and the efficient vacuolar sequestration of Na+. We propose a striking role of D. hansenii vacuoles in the maintenance of constant cytosolic K+ values, even in the presence of extracellular Na+ concentration values more than two orders of magnitude higher than extracellular K+. Finally, the ability to deal with cytosolic Na+ levels significantly higher than those found in S. cerevisiae, shows the existence of important and specific salt tolerance mechanisms and determinants in D. hansenii.


Assuntos
Adaptação Fisiológica/genética , Debaryomyces/metabolismo , Tolerância ao Sal , Vacúolos/metabolismo , Cátions/metabolismo , Debaryomyces/crescimento & desenvolvimento , Glicerol/metabolismo , Concentração de Íons de Hidrogênio , Potássio/metabolismo , Sódio/metabolismo , Vacúolos/química , Vacúolos/genética
5.
PLoS One ; 9(2): e88180, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24505419

RESUMO

Debaryomyces hansenii is a halotolerant yeast that produces and assimilates a wide variety of polyols. In this work we evaluate polyol transport in D. hansenii CBS 767, detecting the occurrence of polyol/H(+) (and sugar/H(+)) symporter activity, through the transient extracellular alkalinization of unbuffered starved cell suspensions. From the D. hansenii genome database, we selected nine ORFs encoding putative transporter proteins to clone in a centromeric plasmid with C-terminal GFP tagging and screened for polyol/H(+) symporters by heterologous expression in Saccharomyces cerevisiae. Five distinct D. hansenii polyol/H(+) symporters were identified and characterized, with different specificities and affinities for polyols, namely one glycerol-specific (DhStl1), one D-galactitol-specific (DhSgl1, Symporter galactitol/H(+) 1), one D-(+)-chiro-inositol-specific (DhSyi1, Symporter D-(+)-chiro-inositol/H(+) 1), one for D-sorbitol/D-mannitol/ribitol/D-arabitol/D-galactitol (DhSyl1, Symporter Polyols 1) and another for D-sorbitol/D-mannitol/ribitol/D-arabitol (DhSyl2, Symporter Polyols 2). This work contributed to the annotation of new yeast polyol transporters, including two specific for uncommon substrates as galactitol and D-(+)-chiro-inositol.


Assuntos
Transporte Biológico/fisiologia , Debaryomyces/metabolismo , Hidrogênio/metabolismo , Polímeros/metabolismo , Simportadores/metabolismo , Galactose/análogos & derivados , Galactose/metabolismo , Glicerol/metabolismo , Inositol/metabolismo , Manitol/metabolismo , Saccharomyces cerevisiae/metabolismo , Sorbitol/metabolismo , Álcoois Açúcares/metabolismo
6.
Antonie Van Leeuwenhoek ; 99(2): 189-200, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20571862

RESUMO

The apiculate yeasts are the species predominating the first stage of grape must alcoholic fermentation and are important for the production of desired volatile compounds. The aim of the present investigation was to establish a protocol for the enological selection of non-Saccharomyces strains directly isolated from a natural must fermentation during the tumultuous phase. At this scope, fifty Hanseniaspora uvarum isolates were characterized at strain level by employing a new combined PCR-based approach. One isolate representative of each identified strain was used in fermentation assays to assess strain-specific enological properties. The chemical analysis indicated that all the analyzed strains were low producers of acetic acid and hydrogen sulphide, whereas they showed fructophilic character and high glycerol production. Analysis of volatile compounds indicated that one strain could positively affect, during the alcoholic fermentation process, the taste and flavour of alcoholic beverages. The statistical evaluation of obtained results indicated that the selected autochthonous H. uvarum strain possessed physiological and technological properties which satisfy the criteria indicated for non-Saccharomyces wine yeasts selection. Our data suggest that the described protocol could be advantageously applied for the selection of non-Saccharomyces strains suitable for the formulation of mixed or sequential starters together with Saccharomyces cerevisiae.


Assuntos
Biotecnologia/métodos , Etanol/metabolismo , Hanseniaspora/isolamento & purificação , Hanseniaspora/metabolismo , Vinho/microbiologia , Ácido Acético/metabolismo , DNA Fúngico/genética , Genes Fúngicos , Glicerol/metabolismo , Hanseniaspora/química , Hanseniaspora/genética , Sulfeto de Hidrogênio/metabolismo , Reação em Cadeia da Polimerase , Compostos Orgânicos Voláteis/metabolismo
7.
Appl Microbiol Biotechnol ; 90(1): 257-67, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21127857

RESUMO

Glycerol is a major by-product from biodiesel production, and developing new uses for glycerol is imperative to overall economics and sustainability of the biodiesel industry. With the aim of producing xylitol and/or arabitol as the value-added products from glycerol, 214 yeast strains, many osmotolerant, were first screened in this study. No strains were found to produce large amounts of xylitol as the dominant metabolite. Some produced polyol mixtures that might present difficulties to downstream separation and purification. Several Debaryomyces hansenii strains produced arabitol as the predominant metabolite with high yields, and D. hansenii strain SBP-1 (NRRL Y-7483) was chosen for further study on the effects of several growth conditions. The optimal temperature was found to be 30°C. Very low dissolved oxygen concentrations or anaerobic conditions inhibited polyol yields. Arabitol yield improved with increasing initial glycerol concentrations, reaching approximately 50% (w/w) with 150 g/L initial glycerol. However, the osmotic stress created by high salt concentrations (≥50 g/L) negatively affected arabitol production. Addition of glucose and xylose improved arabitol production while addition of sorbitol reduced production. Results from this work show that arabitol is a promising value-added product from glycerol using D. hansenii SBP-1 as the producing strain.


Assuntos
Glicerol/metabolismo , Álcoois Açúcares/metabolismo , Leveduras/metabolismo , Meios de Cultura/metabolismo , Glucose/metabolismo , Oxigênio/metabolismo , Temperatura , Leveduras/crescimento & desenvolvimento
8.
Int J Food Microbiol ; 144(1): 72-80, 2010 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-20880601

RESUMO

The knowledge about wine yeasts remains largely dominated by the extensive studies on Saccharomyces (S.) cerevisiae. Molecular methods, allowing discrimination of both species and strains in winemaking, can profitably be applied for characterization of the microflora occurring in winemaking and for monitoring the fermentation process. Recently, some novel yeast isolates have been described as hybrid between S. cerevisiae and Saccharomyces species, leaving the Saccharomyces strains containing non-Saccharomyces hybrids essentially unexplored. In this study, we have analyzed a yeast strain isolated from "Primitivo" grape (http://www.ispa.cnr.it/index.php?page=collezioni&lang=en accession number 12998) and we found that, in addition to the S. cerevisiae genome, it has acquired genetic material from a non-Saccharomyces species. The study was focused on the analysis of chromosomal and mitochondrial gene sequences (ITS and 26S rRNA, SSU and COXII, ACTIN-1 and TEF), 2D-PAGE mitochondrial proteins, and spore viability. The results allowed us to formulate the hypothesis that in the MSH199 isolate a DNA containing an rDNA sequence from Hanseniaspora vineae, a non-Saccharomyces yeast, was incorporated through homologous recombination in the grape environment where yeast species are propagated. Moreover, physiological characterization showed that the MSH199 isolate possesses high technological quality traits (fermentation performance) and glycerol production, resistance to ethanol, SO2 and temperature) useful for industrial application.


Assuntos
Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Vitis/microbiologia , Dióxido de Carbono/metabolismo , DNA Fúngico/genética , Fermentação , Genoma Fúngico/genética , Glicerol/metabolismo , Hanseniaspora/genética , Hanseniaspora/crescimento & desenvolvimento , Hanseniaspora/metabolismo , Cariotipagem , Proteínas Mitocondriais/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Esporos Fúngicos/crescimento & desenvolvimento , Estresse Fisiológico/fisiologia , Dióxido de Enxofre/metabolismo , Vinho/microbiologia
9.
Prep Biochem Biotechnol ; 40(1): 28-37, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20024792

RESUMO

A strain isolated from waste of a milk products plant and exhibited extracellular lipolytic activity was identified as Debaryomyces hansenii by 5.8S rRNA and 28S rRNA gene sequence analyses. Lipolytic activity was assayed spectrophotometrically by using p-nitrophenylpalmitate. Higher specific lipolytic activities were obtained in the presence of tristearin (0.68 U/mg prot), oleic acid (0.56 U/mg prot), and soybean oil (0.36 U/mg prot) than other triglycerides, fatty acids, and vegetable oils considered as carbon sources. Cheese whey appeared to be a good alternative to lipidic substances for lipolytic activity. Among various organic and inorganic nitrogen sources, soy flour was found to attain the lipolytic activity similar to that provided by universal yeast medium components. This work is the first report on the discussion of lipolytic activity enhancement by D. hansenii through modulating the cultivation medium. It also proposes low cost medium nutrients that could be of industrial value and could serve as basal nutrients for further optimization studies on the lipase production by D. hansenii.


Assuntos
Debaryomyces/enzimologia , Microbiologia Industrial/métodos , Lipase/biossíntese , Lipase/metabolismo , Queijo , Debaryomyces/isolamento & purificação , Gorduras Insaturadas na Dieta/metabolismo , Ácidos Graxos/metabolismo , Glicerol/metabolismo , Resíduos Industriais , Compostos de Nitrogênio/metabolismo , Octoxinol/metabolismo , Triglicerídeos/metabolismo
10.
Antonie Van Leeuwenhoek ; 91(3): 229-35, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17072537

RESUMO

Osmotic stress was studied through the induction of the gene coding for glycerol 3-phosphate dehydrogenase (DhGPD1) in the halotolerant yeast Debaryomyces hansenii. This yeast responded to modifications in turgor pressure by stimulating the transcription of DhGPD1 when exposed to solutes that cause turgor stress (NaCl or sorbitol), but did not respond to water stress mediated by ethanol. In contrast to what has been documented to occur in Saccharomyces cerevisiae, D. hansenii protoplasts did not show induction in the transcription of DhGPD1 showing a limitation in their response to solute stress. The results presented indicate that the presence of the cell wall is of significance for the induction of DhGPD1 and hence for osmotic regulation in halotolerant D. hansenii. It appears that the main osmosensor that links high osmolarity with glycerol accumulation may be of a different nature in this yeast.


Assuntos
Ascomicetos/metabolismo , Parede Celular/metabolismo , Glicerol/metabolismo , Cloreto de Sódio/metabolismo , Regulação Fúngica da Expressão Gênica , Glicerol-3-Fosfato Desidrogenase (NAD+)/genética , Glicerol-3-Fosfato Desidrogenase (NAD+)/metabolismo , Concentração Osmolar , RNA Fúngico/metabolismo , Cloreto de Sódio/farmacologia , Sorbitol/farmacologia , Transcrição Genética
11.
Yeast ; 22(15): 1213-22, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16278930

RESUMO

The highly NaCl-tolerant yeast Debaryomyces hansenii produces and obtains high levels of intracellular glycerol as a compatible solute when grown at high NaCl concentrations. The effect of high NaCl concentrations (4%, 8% and 12% w/v) on the glycerol production and the levels of intra- and extracellular glycerol was determined for two D. hansenii strains with different NaCl tolerance and compared to one strain of the moderately NaCl-tolerant yeast Saccharomyces cerevisiae. Initially, high NaCl tolerance seems to be determined by enhanced glycerol production, due to an increased expression of DhGPD1 and DhGPP2 (AL436338) in D. hansenii and GPD1 and GPP2 in S. cerevisiae; however, the ability to obtain high levels of intracellular glycerol seems to be more important. The two D. hansenii strains had higher levels of intracellular glycerol than the S. cerevisiae strain and were able to obtain high levels of intracellular glycerol, even at very high NaCl concentrations, indicating the presence of, for example, a type of closing channel, as previously described for other yeast species.


Assuntos
Regulação Fúngica da Expressão Gênica , Glicerol/metabolismo , Glicerolfosfato Desidrogenase/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Saccharomycetales/crescimento & desenvolvimento , Cloreto de Sódio/farmacologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Glicerolfosfato Desidrogenase/genética , Resposta ao Choque Térmico , Monoéster Fosfórico Hidrolases/genética , Saccharomycetales/enzimologia , Saccharomycetales/genética , Saccharomycetales/fisiologia , Cloreto de Sódio/metabolismo
12.
Curr Microbiol ; 51(2): 87-90, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16049663

RESUMO

The role for the gene encoding glycerol 3-phosphate dehydrogenase (DhGPD1) from the osmotolerant yeast Debaryomyces hansenii, in glycerol production and halotolerance, was studied through its heterologous expression in a Saccharomyces cerevisiae strain deficient in glycerol synthesis (gpd1Delta). The expression of the DhGPD1 gene in the gpd1Delta background restored glycerol production and halotolerance to wild type levels, corroborating its role in the salt-induced production of glycerol. Although the gene was functional in S. cerevisiae, its heterologous expression was not efficient, suggesting that the regulatory mechanism may not be shared by these two yeasts.


Assuntos
Glicerolfosfato Desidrogenase/metabolismo , Saccharomyces cerevisiae/genética , Saccharomycetales/metabolismo , Regulação Fúngica da Expressão Gênica/genética , Glicerol/metabolismo , Glicerolfosfato Desidrogenase/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/enzimologia , Saccharomycetales/crescimento & desenvolvimento , Cloreto de Sódio/farmacologia
13.
FEMS Yeast Res ; 5(8): 693-701, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15943004

RESUMO

The yeast Debaryomyces hansenii is usually found in salty environments such as the sea and salted food. It is capable of accumulating sodium without being intoxicated even when potassium is present at low concentration in the environment. In addition, sodium improves growth and protects D. hansenii in the presence of additional stress factors such as high temperature and extreme pH. An array of advantageous factors, as compared with Saccharomyces cerevisiae, is putatively involved in the increased halotolerance of D. hansenii: glycerol, the main compatible solute, is kept inside the cell by an active glycerol-Na+ symporter; potassium uptake is not inhibited by sodium; sodium protein targets in D. hansenii seem to be more resistant. The whole genome of D. hansenii has been sequenced and is now available at http://cbi.labri.fr/Genolevures/ and, so far, no genes specifically responsible for the halotolerant behaviour of D. hansenii have been found.


Assuntos
Ascomicetos/fisiologia , Ascomicetos/genética , Ascomicetos/metabolismo , Transporte Biológico , Cátions Monovalentes , Glicerol/metabolismo , Temperatura Alta , Concentração de Íons de Hidrogênio , Transporte de Íons , Potássio/metabolismo , Cloreto de Sódio/metabolismo
14.
FEMS Yeast Res ; 3(2): 211-6, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12702454

RESUMO

The physiology of Hanseniaspora guilliermondii was studied under aerobic glucose-limited conditions using the accelerostat procedure (continuous acceleration of dilution rate) and classical chemostat cultures. By both cultivation techniques this yeast was found to be Crabtree-positive. Up to a dilution rate of 0.25 h(-1), glucose was completely metabolised into biomass, glycerol and carbon dioxide. Above this value, an increase in the dilution rate was accompanied by the production of other metabolites like ethanol, acetic and malic acids. Biomass yield during the purely oxidative growth was 0.49 g g(-1) and decreased to 0.26 g g(-1) for D=0.34 h(-1). A maximal specific ethanol production rate of 1.36 mmol g(-1) h(-1) and a maximal ethanol yield of 0.05 g g(-1) were achieved at D=0.34 h(-1).


Assuntos
Etanol/metabolismo , Glucose/metabolismo , Saccharomycetales/fisiologia , Aerobiose , Biomassa , Reatores Biológicos , Dióxido de Carbono/metabolismo , Glicerol/metabolismo , Consumo de Oxigênio/fisiologia , Saccharomycetales/crescimento & desenvolvimento , Saccharomycetales/metabolismo , Vitis/microbiologia
15.
Microbiology (Reading) ; 145 ( Pt 9): 2577-2585, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10517611

RESUMO

A comparison of 42 yeast species with respect to growth in the presence of high NaCl concentration and characteristics of glycerol uptake is presented. The yeast species were classified into four classes on the basis of their ability to grow in the presence of 1, 2, 3 or 4 M NaCl. Considering that two different types of active-transport systems for glycerol uptake have been described, Na+/glycerol and H+/glycerol symports, glycerol transport was investigated by testing for proton uptake upon glycerol addition in cells incubated in the absence and in the presence of NaCl. Only strains belonging to the two higher classes of salt tolerance showed constitutive active glycerol uptake, and could accumulate glycerol internally against a concentration gradient. Five of these strains exhibited a H+/glycerol symport. All the other strains showed evidence of the activity of a salt-dependent glycerol uptake similar to that described in the literature for Debraryomyces hansenii. The strains within the two lower classes of salt tolerance showed, to varying degrees, glycerol active uptake only when glycerol was used as the carbon and energy source, suggesting that this uptake system is involved in glycerol catabolism. The results within this work suggest that active glycerol uptake provides a basis for high halotolerance, helping to maintain a favourable intracellular concentration of glycerol. The relation between the constitutive expression of such carriers and a higher level of salt-stress resistance suggests that this may be an evolutionary advantage for growth under such conditions.


Assuntos
Glicerol/metabolismo , Prótons , Cloreto de Sódio/farmacologia , Leveduras/metabolismo , Transporte Biológico Ativo , Glucose/metabolismo , Cinética , Concentração Osmolar , Leveduras/classificação , Leveduras/efeitos dos fármacos , Leveduras/crescimento & desenvolvimento
16.
J Appl Microbiol ; 82(5): 615-8, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9172403

RESUMO

Ninety-six strains of apiculate wine yeasts were studied for their ability to produce glycerol, acetaldehyde, ethyl acetate, sulphur dioxide and hydrogen sulphide in synthetic medium. Hanseniaspora guilliermondii produced smaller quantities of glycerol, acetaldehyde and hydrogen sulphide than Kloeckera apiculata, whereas the production of ethyl acetate and sulphur dioxide was found to be similar. Strains characterized by different capacities and properties were found for both species. The existence of apiculate strains differing in secondary compound production is of technological interest, as these yeasts constitute potential flavour producers. Selected strains of apiculate yeasts might favour an enhanced flavour formation and yield desirable characteristics to the final product.


Assuntos
Fermentação , Glicerol/metabolismo , Fungos Mitospóricos/metabolismo , Saccharomycetales/metabolismo , Vinho/microbiologia , Acetaldeído/metabolismo , Acetatos/metabolismo , Etanol/metabolismo , Força da Mão , Sulfeto de Hidrogênio/metabolismo , Dióxido de Enxofre/metabolismo
17.
Mol Microbiol ; 24(1): 203-16, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9140977

RESUMO

Aspergillus nidulans conidiospores contain high levels of the non-reducing disaccharide trehalose. We show that upon induction of conidiospore germination, the trehalose pool is rapidly degraded and a glycerol pool is transiently accumulated. A trehalase with an acidic pH optimum was purified from conidiospores. Characterization of the treA gene encoding this trehalase shows that it is homologous to Saccharomyces cerevisiae vacuolar acid trehalase, the product of the ATH1 gene, and to two related proteins of unknown function identified in Mycobacterium tuberculosis and Mycobacterium leprae. A. nidulans mutants that lack acid trehalase activity were constructed by gene replacement at the treA locus. Analysis of these mutants suggests that the treA gene product is localized in the conidiospore wall, is required for growth on trehalose as a carbon source, and is not involved in the mobilization of the intracellular pool of trehalose. Therefore, it is proposed that a cytoplasmic regulatory trehalase is controlling this latter process.


Assuntos
Aspergillus nidulans/enzimologia , Dissacaridases/genética , Proteínas Fúngicas/genética , Trealase/genética , Trealose/metabolismo , Sequência de Aminoácidos , Aspergillus nidulans/genética , Aspergillus nidulans/crescimento & desenvolvimento , Sequência de Bases , Carbono , DNA Fúngico , Dissacaridases/química , Dissacaridases/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Glicerol/metabolismo , Manitol/metabolismo , Dados de Sequência Molecular , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Solubilidade , Esporos Fúngicos/metabolismo , Trealase/química , Trealase/metabolismo , Trealose/farmacologia
18.
Microbiology (Reading) ; 143 ( Pt 4): 1133-1139, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9141676

RESUMO

The toxic effect of NaCl and KCl on growth of the marine yeast Debaryomyces hansenii on glucose or glycerol was studied. Above a threshold value, both salts reduced the specific growth rate, specific glucose and glycerol respiration rates and specific glucose fermentation rate, as well as biomass yields. The exponential inhibition constant, k, and minimum toxic concentration, Cmin were similar for all physiological parameters assayed. The effect of either salt on the specific activity of several glycolytic enzymes showed a similar inhibition pattern, although at much lower salt concentrations compared with the physiological parameters. In agreement with published results on glycerol phosphate dehydrogenase stimulation by salt, we present evidence that a general glycolytic flux deviation could occur naturally during salt stress, due to the intrinsic sensitivity of the glycolytic enzymes to intracellular ion concentrations.


Assuntos
Saccharomycetales/fisiologia , Equilíbrio Hidroeletrolítico , Fermentação , Glucose/metabolismo , Glicerol/metabolismo , Glicólise , Biologia Marinha , Consumo de Oxigênio , Cloreto de Potássio/toxicidade , Saccharomycetales/efeitos dos fármacos , Cloreto de Sódio/toxicidade , Microbiologia da Água
19.
Yeast ; 11(4): 327-36, 1995 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-7785333

RESUMO

The physiology of Hanseniaspora uvarum K5 was studied in glucose-limited chemostat cultures and upon glucose pulse. Up to a dilution rate of 0.28 h-1, glucose was completely metabolized in biomass and CO2. Above this value, increase in the dilution rate was accompanied by sequential production of metabolites (glycerol, acetate and ethanol) and decrease in cell yield. Similar results were observed upon glucose pulse. From the enzyme activities (pyruvate dehydrogenase, pyruvate decarboxylase, NAD and NADP-dependent acetaldehyde dehydrogenases, acetyl coenzyme A synthetase and alcohol dehydrogenase) and substrate affinities, the following conclusions were drawn with respect to product formation of cells: (1) pyruvate was preferentially metabolized via pyruvate dehydrogenase, when biomass and CO2 were the only products formed; (2) acetaldehyde formed by pyruvate decarboxylase was preferentially oxidized in acetate by NADP-dependent aldehyde dehydrogenase; acetate accumulation results from insufficient activity of acetyl-CoA synthetase required for the complete oxidation of acetate; (3) acetaldehyde was oxidized in ethanol by alcohol dehydrogenase, in addition to acetate production.


Assuntos
Saccharomycetales/metabolismo , Acetatos/metabolismo , Álcool Desidrogenase/metabolismo , Carbono/metabolismo , Etanol/metabolismo , Fermentação , Glucose/metabolismo , Glicerol/metabolismo , Piruvatos/metabolismo , Ácido Pirúvico
20.
FEMS Microbiol Lett ; 66(2): 163-7, 1991 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-1936945

RESUMO

Analysis of seventeen yeast strains by 13C-NMR spectroscopy has confirmed the significance of glycerol as the sole osmoregulatory solute under salt-stressed conditions, and has shown arabitol to be present in most of the osmotolerant species. Ribitol was detected in some species, including Debaryomyces hansenii, although ribitol accumulation did not correlate with the osmotic pressure of the medium. Relative amounts of arabitol and ribitol decreased in relation to glycerol when the external osmotic pressure was increased. Trehalose was present during exponential growth of some species.


Assuntos
Glicerol/metabolismo , Cloreto de Sódio/farmacologia , Álcoois Açúcares/metabolismo , Trealose/metabolismo , Leveduras/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Ribitol/metabolismo , Equilíbrio Hidroeletrolítico/efeitos dos fármacos , Equilíbrio Hidroeletrolítico/fisiologia , Leveduras/crescimento & desenvolvimento , Leveduras/metabolismo
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