Changes in Nitrogen Compounds in Must and Wine during Fermentation and Biological Aging by Flor Yeasts

Mauricio, Juan Carlos; Valero, Eva; Millán, Carmen; Ortega, José M.

doi:10.1021/jf010005v

Cited by 63 publications

(46 citation statements)

References 29 publications

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“…Examples include cheese ripening by lactic acid bacteria (LAB) (10-12), wine fermentation by Saccharomyces cerevisiae (13,14), and natto fermentation by Bacillus subtilis (15). Despite the severely energy-limiting conditions, microbes manage to survive in these processes for many weeks, while continuing to produce aroma and flavor compounds in the product matrix (10,13,15,16). Another incentive for studying zero-growth physiology is related to the application of microorganisms as cell factories for the production of food ingredients, enzymes, chemicals, and biofuels.…”

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confidence: 99%

Physiological and Transcriptional Responses of Different Industrial Microbes at Near-Zero Specific Growth Rates

Ercan

Bisschops

Overkamp

et al. 2015

Appl Environ Microbiol

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The current knowledge of the physiology and gene expression of industrially relevant microorganisms is largely based on laboratory studies under conditions of rapid growth and high metabolic activity. However, in natural ecosystems and industrial processes, microbes frequently encounter severe calorie restriction. As a consequence, microbial growth rates in such settings can be extremely slow and even approach zero. Furthermore, uncoupling microbial growth from product formation, while cellular integrity and activity are maintained, offers perspectives that are economically highly interesting. Retentostat cultures have been employed to investigate microbial physiology at (near-)zero growth rates. This minireview compares information from recent physiological and gene expression studies on retentostat cultures of the industrially relevant microorganisms Lactobacillus plantarum, Lactococcus lactis, Bacillus subtilis, Saccharomyces cerevisiae, and Aspergillus niger. Shared responses of these organisms to (near-)zero growth rates include increased stress tolerance and a downregulation of genes involved in protein synthesis. Other adaptations, such as changes in morphology and (secondary) metabolite production, were species specific. This comparison underlines the industrial and scientific significance of further research on microbial (near-)zero growth physiology. Most research in microbial physiology focuses on growing cells, although under natural and industrial conditions, microbes frequently encounter a state in which neither growth nor deterioration of cells occurs. However, the experimental design to study microbes in this clearly relevant physiological state is far from trivial.In this minireview, we define zero growth as a nongrowing state in which the viability and metabolic activity of a microbial culture are maintained for prolonged periods. As such, zero growth differs from starvation, which is coupled to cellular deterioration, loss of activity, and ultimately, cell death (1, 2). Zero growth also differs from differentiated survival states, such as bacterial or fungal spores, in which metabolism comes to a standstill (3). Conversely, under zero-growth conditions, microbes exclusively use available substrates for processes that contribute to maintenance of cellular integrity and homeostasis (4-7). Such processes include homeostasis of transmembrane gradients of protons and solutes, defense and repair systems, osmoregulation, and protein turnover (8, 9).In classical food fermentation processes, (near-)zero growth occurs during prolonged periods of extremely restricted availability of energy substrates. Examples include cheese ripening by lactic acid bacteria (LAB) (10-12), wine fermentation by Saccharomyces cerevisiae (13,14), and natto fermentation by Bacillus subtilis (15). Despite the severely energy-limiting conditions, microbes manage to survive in these processes for many weeks, while continuing to produce aroma and flavor compounds in the product matrix (10,13,15,16). Another incentive for studying...

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mentioning

confidence: 99%

Physiological and Transcriptional Responses of Different Industrial Microbes at Near-Zero Specific Growth Rates

Ercan

Bisschops

Overkamp

et al. 2015

Appl Environ Microbiol

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“…Secondly, it is known that the cultivars such as Chardonnay, Riesling, and Sauvignon Blanc contain higher amounts of proline, which cannot be assimilated without oxygen (Stines et al 2000;Mauricio et al 2001;Herbert et al 2005). Thus, if a large proportion of nitrogen is present in the form of proline, yeasts will prefer GABA (Huang et al 2000;Batch et al 2009).…”

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confidence: 99%

Chasing after minerality, relationship to yeasts nutritional stress and succinic acid production

Baroň¹,

Fiala²

2012

Czech J. Food Sci.

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Baroň M., Fiala J. (2012): Chasing after minerality, relationship to yeast nutritional stress and succinic acid production. Czech J. Food Sci., 30: 188-193. Minerality is certainly one of the most mysterious and most valuable tones of wine taste and it is very often associated with the concept of terroir. The isotachophoresis was used for determination of cations -minerals in two wines from vineyards with different soil conditions, with and without exceptional "minerality". However, it was found that it has nothing to do with minerals. More attention was paid to the relationship between the nutritional stress of yeasts and succinic acid production, which can result in a final difference in the taste of wine. In addition, sensory evaluation was used to reveal differences between wines with increasing levels of succinic acid.

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“…The previous results suggest that yeasts readjust a number of mechanisms to maintain their redox balance by synthesizing and releasing some compounds such as L-proline (25). Also, yeasts regulate the production of toxic compounds by triggering detoxification mechanisms such as that involving the production of acetoin and acetate.…”

Section: Discussionmentioning

confidence: 98%

Effects ofADH2Overexpression inSaccharomyces bayanusduring Alcoholic Fermentation

Maestre

García‐Martínez

Peinado

et al. 2008

Appl Environ Microbiol

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The effect of overexpression of the gene ADH2 on metabolic and biological activity in Saccharomyces bayanus V5 during alcoholic fermentation has been evaluated. This gene is known to encode alcohol dehydrogenase II (ADH II). During the biological aging of sherry wines, where yeasts have to grow on ethanol owing to the absence of glucose, this isoenzyme plays a prominent role by converting the ethanol into acetaldehyde and producing NADH in the process. Overexpression of the gene ADH2 during alcoholic fermentation has no effect on the proteomic profile or the net production of some metabolites associated with glycolysis and alcoholic fermentation such as ethanol, acetaldehyde, and glycerol. However, it affects indirectly glucose and ammonium uptakes, cell growth, and intracellular redox potential, which lead to an altered metabolome. The increased contents in acetoin, acetic acid, and L-proline present in the fermentation medium under these conditions can be ascribed to detoxification by removal of excess acetaldehyde and the need to restore and maintain the intracellular redox potential balance.Saccharomyces cerevisiae possesses at least five genes (ADH1 to ADH5) that encode alcohol dehydrogenase isoenzymes involved in ethanol metabolism. The isoenzymes alcohol dehydrogenase I (ADH I), III, IV, and V reduce acetaldehyde to ethanol during alcoholic fermentation. In contrast, ADH II (EC 1.1.1.1) is glucose repressed and catalyzes the reverse reaction (i.e., the oxidation of ethanol to acetaldehyde). Therefore, when glucose in the fermentation medium is depleted, ADH II is the first enzyme in the use of ethanol (11). S. cerevisiae mutants possessing no ADH activity are unable to grow on ethanol as their sole carbon source, so they tend to accumulate large amounts of glycerol as a result (56). Although ADH1 and ADH2 share 89% sequence similarity, their respective expression products, ADH I and ADH II, differ in affinity for the substrate. Thus, the K m value for ADH II for ethanol is 10 times lower than those for the other ADHs (37). Some authors have studied the presence of various transcription factors for the activation (derepression) of the gene ADH2 (10,13,14,40,43,48,53,55).Once alcoholic fermentation completes and fermentable sugars are depleted, some S. cerevisiae strains can switch from a fermentative metabolism to an oxidative (respiratory) metabolism and form a biofilm known as "flor" on the wine surface (24). Biological aging is carried out by such yeast strains (flor yeasts) (5). The molecular basis for the film formation has been the subject of recent study (19,30,52). During biological aging of wine, flor yeasts grow in a medium containing a high ethanol concentration and produce substantial amounts of acetaldehyde (2). The isoenzyme ADH II plays a key role in this process (6,17,24).Overexpression of the ADH2 gene during fermentation can be expected to create conditions of a futile cycle and affect cellular demands for cofactors and also the redox status of the yeast cells.In order to evaluate the imp...

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Changes in Nitrogen Compounds in Must and Wine during Fermentation and Biological Aging by Flor Yeasts

Cited by 63 publications

References 29 publications

Physiological and Transcriptional Responses of Different Industrial Microbes at Near-Zero Specific Growth Rates

Physiological and Transcriptional Responses of Different Industrial Microbes at Near-Zero Specific Growth Rates

Chasing after minerality, relationship to yeasts nutritional stress and succinic acid production

Effects ofADH2Overexpression inSaccharomyces bayanusduring Alcoholic Fermentation

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