Panimopohjahiivojen maltoosin ja maltotrioosin kulutukseen vaikuttavat geneettiset ja ympäristötekijät: Diplomityö

Jyri-Pekka Multanen

Research output: ThesisMaster's thesis

Abstract

The literature survey concentrated on uptake of wort sugars by brewer's lager yeast strains in brewery fermentations. The main focus was on transport of maltose and maltotriose (alfa-glucosides) into yeast across cell membrane. Discussed topics were the transport mechanism, diversity of different transporters and their properties in brewer's yeasts, and factors affecting uptake of fermentable sugars during primary fermentation of beer. Transport of alfa-glucosides is industrially relevant, because it is one of the rate limiting steps in metabolism of yeast, and fast and complete uptake is necessary for an efficient fermentation process. In the experimental part, two alfa-glucoside transporters, Malxl and Mttl of an industrial lager strain were characterized kinetically, using genetically defined laboratory strains, in which one of these is the only alfa-glucoside transporter. Affinities and maximum activities of maltose and maltotriose transport, and their temperature-dependencies, were determined by measuring initial uptake rate of radioactively labelled substrates. It was also studied, how stimulation of yeast cells with glucose prior to transport activity measurement affects the apparent transport activity. The transporter recently found in lager yeasts, Mttl, proved to be a better maltotriose than maltose transporter, and its maltose transport was less sensitive to low temperature than that of the studied Malxl transporter of the same industrial lager strain. Maltose transport of both Malxl and Mttl was clearly less temperature-dependent than that of Agtl transporter in a study Vidgren et al. (2007). The Malxl was primarily a high affinity maltose transporter in agreement with most literature reports concerning Malxl transporters of laboratory strains of S. cerevisiae. The Malxl also transported maltotriose, but with such a low affmity that it is not necessarily of importance regarding wort fermentation. Mttl is probably an important maltotriose transporter for lager yeasts in primary fermentation. Transport activity of growing laboratory yeast increased markedly with 2-10 minute incubation with glucose prior to transport activity assay, and the effect was greater with yeast suspension stored at starving conditions at 0°C. The activity decreased during storage, probably due to both inactivation of transporters and decrease in energy charge. Activity of industrially cropped lager yeast, taken from a recycled yeast storage tank, did not decrease during storage. The effect of glucose stimulation was smaller than for the laboratory yeasts studied.
Original languageEnglish
QualificationMaster Degree
Awarding Institution
  • Helsinki University of Technology
Supervisors/Advisors
  • Leisola, Matti, Supervisor, External person
  • Londesborough, John, Advisor, External person
Place of PublicationEspoo
Publisher
Publication statusPublished - 2008
MoE publication typeG2 Master's thesis, polytechnic Master's thesis

Fingerprint

transporters
brewers yeast
maltotriose
maltose
yeasts
fermentation
glucosides
uptake mechanisms
wort (brewing)
glucose
sugars
temperature
brewing industry
beers
cell membranes
inactivation
metabolism
energy
assays

Cite this

Multanen, Jyri-Pekka. / Panimopohjahiivojen maltoosin ja maltotrioosin kulutukseen vaikuttavat geneettiset ja ympäristötekijät : Diplomityö. Espoo : Helsinki University of Technology, 2008. 73 p.
@phdthesis{03c1f9d14d8d4553804be6040c85b028,
title = "Panimopohjahiivojen maltoosin ja maltotrioosin kulutukseen vaikuttavat geneettiset ja ymp{\"a}rist{\"o}tekij{\"a}t: Diplomity{\"o}",
abstract = "The literature survey concentrated on uptake of wort sugars by brewer's lager yeast strains in brewery fermentations. The main focus was on transport of maltose and maltotriose (alfa-glucosides) into yeast across cell membrane. Discussed topics were the transport mechanism, diversity of different transporters and their properties in brewer's yeasts, and factors affecting uptake of fermentable sugars during primary fermentation of beer. Transport of alfa-glucosides is industrially relevant, because it is one of the rate limiting steps in metabolism of yeast, and fast and complete uptake is necessary for an efficient fermentation process. In the experimental part, two alfa-glucoside transporters, Malxl and Mttl of an industrial lager strain were characterized kinetically, using genetically defined laboratory strains, in which one of these is the only alfa-glucoside transporter. Affinities and maximum activities of maltose and maltotriose transport, and their temperature-dependencies, were determined by measuring initial uptake rate of radioactively labelled substrates. It was also studied, how stimulation of yeast cells with glucose prior to transport activity measurement affects the apparent transport activity. The transporter recently found in lager yeasts, Mttl, proved to be a better maltotriose than maltose transporter, and its maltose transport was less sensitive to low temperature than that of the studied Malxl transporter of the same industrial lager strain. Maltose transport of both Malxl and Mttl was clearly less temperature-dependent than that of Agtl transporter in a study Vidgren et al. (2007). The Malxl was primarily a high affinity maltose transporter in agreement with most literature reports concerning Malxl transporters of laboratory strains of S. cerevisiae. The Malxl also transported maltotriose, but with such a low affmity that it is not necessarily of importance regarding wort fermentation. Mttl is probably an important maltotriose transporter for lager yeasts in primary fermentation. Transport activity of growing laboratory yeast increased markedly with 2-10 minute incubation with glucose prior to transport activity assay, and the effect was greater with yeast suspension stored at starving conditions at 0°C. The activity decreased during storage, probably due to both inactivation of transporters and decrease in energy charge. Activity of industrially cropped lager yeast, taken from a recycled yeast storage tank, did not decrease during storage. The effect of glucose stimulation was smaller than for the laboratory yeasts studied.",
author = "Jyri-Pekka Multanen",
note = "HUO: NT Food Solutions CA2: TK402",
year = "2008",
language = "English",
publisher = "Helsinki University of Technology",
address = "Finland",
school = "Helsinki University of Technology",

}

Multanen, J-P 2008, 'Panimopohjahiivojen maltoosin ja maltotrioosin kulutukseen vaikuttavat geneettiset ja ympäristötekijät: Diplomityö', Master Degree, Helsinki University of Technology, Espoo.

Panimopohjahiivojen maltoosin ja maltotrioosin kulutukseen vaikuttavat geneettiset ja ympäristötekijät : Diplomityö. / Multanen, Jyri-Pekka.

Espoo : Helsinki University of Technology, 2008. 73 p.

Research output: ThesisMaster's thesis

TY - THES

T1 - Panimopohjahiivojen maltoosin ja maltotrioosin kulutukseen vaikuttavat geneettiset ja ympäristötekijät

T2 - Diplomityö

AU - Multanen, Jyri-Pekka

N1 - HUO: NT Food Solutions CA2: TK402

PY - 2008

Y1 - 2008

N2 - The literature survey concentrated on uptake of wort sugars by brewer's lager yeast strains in brewery fermentations. The main focus was on transport of maltose and maltotriose (alfa-glucosides) into yeast across cell membrane. Discussed topics were the transport mechanism, diversity of different transporters and their properties in brewer's yeasts, and factors affecting uptake of fermentable sugars during primary fermentation of beer. Transport of alfa-glucosides is industrially relevant, because it is one of the rate limiting steps in metabolism of yeast, and fast and complete uptake is necessary for an efficient fermentation process. In the experimental part, two alfa-glucoside transporters, Malxl and Mttl of an industrial lager strain were characterized kinetically, using genetically defined laboratory strains, in which one of these is the only alfa-glucoside transporter. Affinities and maximum activities of maltose and maltotriose transport, and their temperature-dependencies, were determined by measuring initial uptake rate of radioactively labelled substrates. It was also studied, how stimulation of yeast cells with glucose prior to transport activity measurement affects the apparent transport activity. The transporter recently found in lager yeasts, Mttl, proved to be a better maltotriose than maltose transporter, and its maltose transport was less sensitive to low temperature than that of the studied Malxl transporter of the same industrial lager strain. Maltose transport of both Malxl and Mttl was clearly less temperature-dependent than that of Agtl transporter in a study Vidgren et al. (2007). The Malxl was primarily a high affinity maltose transporter in agreement with most literature reports concerning Malxl transporters of laboratory strains of S. cerevisiae. The Malxl also transported maltotriose, but with such a low affmity that it is not necessarily of importance regarding wort fermentation. Mttl is probably an important maltotriose transporter for lager yeasts in primary fermentation. Transport activity of growing laboratory yeast increased markedly with 2-10 minute incubation with glucose prior to transport activity assay, and the effect was greater with yeast suspension stored at starving conditions at 0°C. The activity decreased during storage, probably due to both inactivation of transporters and decrease in energy charge. Activity of industrially cropped lager yeast, taken from a recycled yeast storage tank, did not decrease during storage. The effect of glucose stimulation was smaller than for the laboratory yeasts studied.

AB - The literature survey concentrated on uptake of wort sugars by brewer's lager yeast strains in brewery fermentations. The main focus was on transport of maltose and maltotriose (alfa-glucosides) into yeast across cell membrane. Discussed topics were the transport mechanism, diversity of different transporters and their properties in brewer's yeasts, and factors affecting uptake of fermentable sugars during primary fermentation of beer. Transport of alfa-glucosides is industrially relevant, because it is one of the rate limiting steps in metabolism of yeast, and fast and complete uptake is necessary for an efficient fermentation process. In the experimental part, two alfa-glucoside transporters, Malxl and Mttl of an industrial lager strain were characterized kinetically, using genetically defined laboratory strains, in which one of these is the only alfa-glucoside transporter. Affinities and maximum activities of maltose and maltotriose transport, and their temperature-dependencies, were determined by measuring initial uptake rate of radioactively labelled substrates. It was also studied, how stimulation of yeast cells with glucose prior to transport activity measurement affects the apparent transport activity. The transporter recently found in lager yeasts, Mttl, proved to be a better maltotriose than maltose transporter, and its maltose transport was less sensitive to low temperature than that of the studied Malxl transporter of the same industrial lager strain. Maltose transport of both Malxl and Mttl was clearly less temperature-dependent than that of Agtl transporter in a study Vidgren et al. (2007). The Malxl was primarily a high affinity maltose transporter in agreement with most literature reports concerning Malxl transporters of laboratory strains of S. cerevisiae. The Malxl also transported maltotriose, but with such a low affmity that it is not necessarily of importance regarding wort fermentation. Mttl is probably an important maltotriose transporter for lager yeasts in primary fermentation. Transport activity of growing laboratory yeast increased markedly with 2-10 minute incubation with glucose prior to transport activity assay, and the effect was greater with yeast suspension stored at starving conditions at 0°C. The activity decreased during storage, probably due to both inactivation of transporters and decrease in energy charge. Activity of industrially cropped lager yeast, taken from a recycled yeast storage tank, did not decrease during storage. The effect of glucose stimulation was smaller than for the laboratory yeasts studied.

M3 - Master's thesis

PB - Helsinki University of Technology

CY - Espoo

ER -