Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis

Growth and β-galactosidase (β-gal) expression were characterized in the yeast Kluyveromyces lactis strain NRRL Y-1118 growing in aerobic chemostat cultures under carbon, nitrogen or phosphate limitation. In lactose or galactose-limited cultures, β-gal accumulated in amounts equivalent to 10-12% of t...

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Autores principales: Inchaurrondo, V. A., Flores, M. V., Voget, Claudio Enrique
Formato: Articulo
Lenguaje:Español
Publicado: 1998
Materias:
Ciencias Exactas
Biología
Kluyveromyces lactis
b-galactosidase
continuous culture
enzyme expression
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/140219
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-140219
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Español
topic Ciencias Exactas
Biología
Kluyveromyces lactis
b-galactosidase
continuous culture
enzyme expression
spellingShingle Ciencias Exactas
Biología
Kluyveromyces lactis
b-galactosidase
continuous culture
enzyme expression
Inchaurrondo, V. A.
Flores, M. V.
Voget, Claudio Enrique
Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis
topic_facet Ciencias Exactas
Biología
Kluyveromyces lactis
b-galactosidase
continuous culture
enzyme expression
description Growth and β-galactosidase (β-gal) expression were characterized in the yeast Kluyveromyces lactis strain NRRL Y-1118 growing in aerobic chemostat cultures under carbon, nitrogen or phosphate limitation. In lactose or galactose-limited cultures, β-gal accumulated in amounts equivalent to 10-12% of the total cell protein. The induced β-gal expression was repressed when cells were grown under N- or P-limitation. In lactose medium, enzyme levels were 4-8 times lower than those expressed in C-limited cultures. A similar response was observed when galactose was the carbon source. These results suggest that a galactose-dependent signal (in addition to glucose) may have limited induction when cells were grown in carbon-sufficient cultures. Constitutive β-gal expression was highest in lactate-limited and lowest in glucose-limited media and was also repressed in glucose-sufficient cultures. Other K. lactis strains (NRRL Y-1140 and CBS 2360) also showed glucose repression (although with different sensitivity) under non-inducing conditions. We infer that these strains share a common mechanism of glucose repression independent of the induction pathway. The kinetics of β-gal induction observed in C-limited cultures confirms that β-gal induction is a short-term enzyme adaptation process. Applying a lactose pulse to a lactose-limited chemostat culture resulted in 'substrate-accelerated death'. Immediately after the pulse, growth was arrested and β-gal was progressively inactivated. Yeast metabolism in C-limited cultures was typically oxidative with the substrate being metabolized solely to biomass and CO 2 . Cells grown under P- or N-limitation, either with glucose or lactose, exhibited higher rates of sugar consumption than C-limited cells, accumulated intracellular reserve carbohydrates and secreted metabolic products derived from the glycolytic pathway, mainly glycerol and ethanol.
format Articulo
Articulo
author Inchaurrondo, V. A.
Flores, M. V.
Voget, Claudio Enrique
author_facet Inchaurrondo, V. A.
Flores, M. V.
Voget, Claudio Enrique
author_sort Inchaurrondo, V. A.
title Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis
title_short Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis
title_full Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis
title_fullStr Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis
title_full_unstemmed Growth and β-galactosidase synthesis in aerobic chemostat cultures of Kluyveromyces lactis
title_sort growth and β-galactosidase synthesis in aerobic chemostat cultures of kluyveromyces lactis
publishDate 1998
url http://sedici.unlp.edu.ar/handle/10915/140219
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AT floresmv growthandbgalactosidasesynthesisinaerobicchemostatculturesofkluyveromyceslactis
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