Modification of Saccharomyces cerevisiae thermotolerance following rapid exposure to acid stress.
Thermotolerance was induced in cells of Saccharomyces cerevisiae YPH499 pre-exposed, during 10 min and in the presence of glucose, to a mild acid-stress with HCl at pH 3.5. Thermotolerance was not induced in cells exposed to a severe acid stress by 50 mM acetic acid at pH 3.5, or HCl at pH 2.5 or pH 2.0. Yeast cells pre-incubated under glucose starvation were found to be more tolerant to a lethal heat stress than cells pre-incubated in glucose-supplemented media, despite the pH value of the media (range 2.0-6.5) and the type of acidulant used (HCl or acetic acid). Moreover, the high thermotolerance exhibited by cells pre-incubated at pH 6.5 for 10 min under glucose starvation was not significantly modified by the acidification of the pre-incubation medium. Results are discussed based on the effect that glucose and a mild or severe acid stress have on plasma membrane H+-ATPase activity and on cytosolic pH values, estimated in a previous work.
Carmelo
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V
Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Lisboa, Portugal.
Santos
R
R
Viegas
C A
CA
Sá-Correia
I
I
D019342:Acetic Acid / Q000737:chemistry*; D015169:Colony Count, Microbial; D005947:Glucose / Q000378:metabolism; D006358:Hot Temperature; D006851:Hydrochloric Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*
D005947:Glucose; D019342:Acetic Acid; D006851:Hydrochloric Acid