Maltose and Maltotriose Active Transport and Fermentation by<i>Saccharomyces Cerevisiaes</i>

Alves-Jr, Sergio L; Herberts, Ricardo André; Hollatz, Cláudia; Miletti, Luiz Cláudio; Stambuk, Boris U.

doi:10.1094/asbcj-2007-0411-01

Cited by 35 publications

(53 citation statements)

References 39 publications

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“…4), indicating that the AGT1 transporter is the only fully competent maltotriose permease in S. cerevisiae. The low affinity of the AGT1 permease for maltose and maltotriose in the wild-type strains analyzed is in accordance with data obtained with other unrelated strains (1,32) and would explain the lower rates of maltotriose consumption from malt extract (Fig. 3) than of maltose uptake by the same cells.…”

Section: Discussionsupporting

confidence: 89%

“…In our experiments, the kinetic parameters were determined by the initial rates of H ϩ influx (Ͻ10 s) triggered by the cotransport of the sugar, and therefore, these experimental artifacts were avoided. The importance of the AGT1 permease for maltotriose active transport and fermentation is also evident from recent data showing that constitutive and enhanced expression of this gene is required for efficient maltotriose fermentation by S. cerevisiae (1,36). The recent discovery of new AGT1 alleles in industrial yeast strains (39), some of which seem to transport maltotriose more efficiently (30), opens new opportunities to increase yeast fitness for the fermentation of starch hydrolysates, preventing incomplete or sluggish maltotriose fermentations.…”

Section: Discussionmentioning

confidence: 97%

“…Glucose was assessed by the glucose oxidase and peroxidase method using a commercial kit (BioDiagnostica-Laborclin). Maltose and maltotriose were assessed spectrophotometrically at 540 nm with methylamine in 0.25 M NaOH as described previously (1). Sugars were also analyzed by thinlayer chromatography (TLC) on silica gel 60 TLC sheets using 5:2:1 (vol/vol/vol) n-butanol-ethanol-water as the solvent.…”

Section: Vol 74 2008 Agt1 Permease Required For Maltotriose Fermentmentioning

confidence: 99%

“…The positions of different sugars (10 g each of glucose, maltose, and maltotriose) in each sample and the positions of standard compounds on the TLC plates were determined with sulfuric acid as described elsewhere (34). Ethanol was assessed with alcohol oxidase and peroxidase as described previously (1,3).…”

Section: Vol 74 2008 Agt1 Permease Required For Maltotriose Fermentmentioning

confidence: 99%

“…The molecular identity of maltotriose transporters in S. cerevisiae remained largely unknown until some years ago when a new permease gene, designated AGT1, in a partially functional mal1g locus was characterized (16). The AGT1 H ϩ symporter transports a series of ␣-glucosides (35) and has high affinity (K m , ϳ8 mM) for trehalose and sucrose and significantly lower affinity (K m , ϳ20 to 35 mM) for maltose, maltotriose, and ␣-methylglucoside (1,4,32,33). In accordance with the importance of maltotriose transport for the industrial application of yeasts, practically all brewing strains have the AGT1 permease gene in their genomes, and transcriptome studies have also shown high levels of expression of this gene during wort fermentation (19,20,23,39).…”

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Molecular Analysis of Maltotriose Active Transport and Fermentation by Saccharomyces cerevisiae Reveals a Determinant Role for the AGT1 Permease

Alves

Herberts

Hollatz

et al. 2008

Appl Environ Microbiol

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Incomplete and/or sluggish maltotriose fermentation causes both quality and economic problems in the ale-brewing industry. Although it has been proposed previously that the sugar uptake must be responsible for these undesirable phenotypes, there have been conflicting reports on whether all the known ␣-glucoside transporters in Saccharomyces cerevisiae (MALx1, AGT1, and MPH2 and MPH3 transporters) allow efficient maltotriose utilization by yeast cells. We characterized the kinetics of yeast cell growth, sugar consumption, and ethanol production during maltose or maltotriose utilization by several S. cerevisiae yeast strains (both MAL constitutive and MAL inducible) and by their isogenic counterparts with specific deletions of the AGT1 gene. Our results clearly showed that yeast strains carrying functional permeases encoded by the MAL21, MAL31, and/or MAL41 gene in their plasma membranes were unable to utilize maltotriose. While both highand low-affinity transport activities were responsible for maltose uptake from the medium, in the case of maltotriose, the only low-affinity (K m , 36 ؎ 2 mM) transport activity was mediated by the AGT1 permease. In conclusion, the AGT1 transporter is required for efficient maltotriose fermentation by S. cerevisiae yeasts, highlighting the importance of this permease for breeding and/or selection programs aimed at improving sluggish maltotriose fermentations.Several important industrial applications of the yeast Saccharomyces cerevisiae, such as brewing, baking, and the production of distilled beverages, rely on the efficient fermentation of starch hydrolysates rich in glucose and in the ␣-glucosides maltose and maltotriose. In brewer's wort, for example, the most abundant fermentable sugar is maltose (50 to 60%), followed by maltotriose (15 to 20%) and glucose (10 to 15%). Of these sugars, glucose is preferentially and rapidly utilized by the yeast cells, but process efficiency also requires the complete fermentation of both maltose and maltotriose. After glucose exhaustion, maltose is easily fermented by the majority of S. cerevisiae strains, and not only is maltotriose the least preferred sugar for uptake by these yeast cells, but many yeasts may not use it at all (23, 37, 44). The difficulty that some strains have in consuming maltotriose leads to one of the problems experienced by many breweries, namely, a high content of residual sugar in the finished beer, low ethanol yields, and atypical beer flavor profiles. Therefore, the rate of uptake and fermentation of maltotriose is one of the major determinants of fermentation efficiency and product quality. Due to its relevance for beer fermentation, maltotriose utilization has been studied mostly with the two classes of yeast strains used for brewing, S. cerevisiae ale strains and S. pastorianus lager strains. These studies have revealed that maltotriose utilization by ale strains is significantly slower than that by lager yeasts and that, consequently, residual maltotriose is more common at the end of ale fermentations (22,23,44...

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 97%

Section: Vol 74 2008 Agt1 Permease Required For Maltotriose Fermentmentioning

confidence: 99%

Section: Vol 74 2008 Agt1 Permease Required For Maltotriose Fermentmentioning

confidence: 99%

mentioning

confidence: 99%

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Molecular Analysis of Maltotriose Active Transport and Fermentation by Saccharomyces cerevisiae Reveals a Determinant Role for the AGT1 Permease

Alves

Herberts

Hollatz

et al. 2008

Appl Environ Microbiol

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Biochemistry of Beer Fermentation

Willaert¹

2012

Food Biochemistry and Food Processing

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Characterization of the Saccharomyces bayanus-type AGT1 transporter of lager yeast

Vidgren

Londesborough

2012

J. Inst. Brew.

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Transport of maltose and maltotriose into the yeast cell is thought to be rate‐limiting in the utilization of these sugars. The maltose and maltotriose transporters Malx1, Agt1, Mtt1 and Mphx are present in different combinations in brewer's yeast strains, conferring different maltose and maltotriose transport characteristics on the strains. A new putative maltose/maltotriose transporter ORF was identified during whole genome sequencing of the lager strain WS34/70 (Y. Nakao et al., DNA Res., 2009, 16, 115–129). Sequence comparisons suggested that this putative α‐glucoside transporter might be a Saccharomyces bayanus counterpart of the Agt1 (Saccharomyces cerevisiae type) transporter. In the present work, the transporter coded by a SbAGT1 gene from a lager strain, A15 (and with the same sequence as the corresponding gene in WS34/70) was characterized. It is shown that this SbAGT1 encodes a functional α‐glucoside transporter with a wide‐substrate range, including maltose and maltotriose. Trehalose, α‐methylglucoside and sucrose were inhibitors, suggesting they are also substrates. The SbAgt1 transporter had similar affinities for maltose and maltotriose (17 ± 7 and 22 ± 2 m m, respectively) and a higher Vmax for maltose than maltotriose (21 ± 7 and 12 ± 2 µmol min−1 g dry yeast−1, respectively). Copyright © 2012 The Institute of Brewing & Distilling

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Maltose and Maltotriose Active Transport and Fermentation bySaccharomyces Cerevisiaes

Cited by 35 publications

References 39 publications

Molecular Analysis of Maltotriose Active Transport and Fermentation by Saccharomyces cerevisiae Reveals a Determinant Role for the AGT1 Permease

Molecular Analysis of Maltotriose Active Transport and Fermentation by Saccharomyces cerevisiae Reveals a Determinant Role for the AGT1 Permease

Biochemistry of Beer Fermentation

Characterization of the Saccharomyces bayanus-type AGT1 transporter of lager yeast

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