Incubation at Low Temperatures Increases Biomass Yield in Yeasts Isolated from Cold Environments
Pilar Gonzalo, María José Valderrama, Maria Isabel De Siloniz*, José M. Peinado
Dpto. Microbiología, Facultad de Biología, Universidad Complutense, Madrid 28040, Spain
Article history:
Received September 10, 1997
Accepted November 5, 1997
Key words:
psychrotolerance, low temperatures, spoilage yeasts
Summary:
The growth kinetics of several cold-tolerant yeast strains (Candida colliculosa, Candida krusei, Debaryomyces hansenii, Kluyveromyccs marxianus and Torulaspora delbrueckii), isolated from refrigerated food, were studied over a range of temperatures (10-30 °C). For comparison, a mesophilic Saccharomyces cerevisiae strain was also included. The specific growth rates at different temperatures were very similar in the cold-tolerant isolates and the mesophilic strain; µ (h-1) increased with temperature, reaching a maximum at 30 °C. Nevertheless, biomass yields did not correlate luith the observed growth rates: maximum yields were attained at low temperatures (10 °C), at which the lowest specific growth rates were measured, and low yields were produced at 30 °C where the highest growth rates were observed. On the contrary, Sacch. cerevisiae did not show this behaviour. The variation of glucose consumption rates at the studied temperatures, correlated with the growth rates observed, but again not with the measured yields. Fermentation (mmol ethanol formed/mmol glucose consumed) was not affected by incubation temperature. These data were compared with our data for Candida sake Antarctic strains, which exhibited a similar reponse. Based on that, the enhancement of yield at low temperatures could be considered as a consequence of cold tolerance in yeasts, allowing well adapted strains to develop efficiently, albeit at reduced rates, in low temperature environments.
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