Fed-batch cultivation of bakers' yeast: Effect of nutrient depletion and heat stress on cell composition

Ertugay, N
Hamamci, H
Bayındırlı, Alev
The physiology of a commercial strain of bakers' yeast was studied in terms of the cell composition under different growth conditions and of its response to stress. The study comprised fed-batch experiments since this is the system used in bakers' yeast industry. The classical fed-batch fermentation procedure was modified in that the yeast cells were continuously grown to a steady-state at a dilution rate of 0.1/h in order to achieve more or less the same initial starting point in terms of cell composition. This steady-state culture was then switched to fed-batch concomitantly with exposure to stress. The highest amount of trehalose accumulation was achieved when nutrient depletion and heat stress were applied concomitantly. The highest amount of trehalose, 12 %, was attained in cells stressed by both nitrogen depletion and heat stress. The protein content remained constant, although with some oscillations, at a value of 30 % throughout this dual stress experiment.


BASALP, A; Özcengiz, Gülay; ALAEDDINOGLU, NG (Springer Science and Business Media LLC, 1992-03-01)
Bacilysin biosynthesis and alkaline serine protease production in Bacillus subtilis 168 were monitored and compared in batch cultures when various effectors of sporulation were added at different stages of growth in a medium containing sucrose and glutamate. Depending on the time of addition, glucose affected sporulation and serine protease formation to the same extent, but had no effect on bacilysin production. Ammonium and L-alanine additions suppressed all three processes. Casamino acids severely interfe...
High hydrostatic pressure induced inactivation kinetics of e. coli o157:h7 and s. aureus in carrot juice and analysis of cell volume change
Pilavtepe, Mutlu; Alpas, Hami; Department of Food Engineering (2007)
The main objective of this study was to determine the pressure induced inactivation mechanism of pressure-resistant Escherichia coli O157:H7 933 and Staphylococcus aureus 485 in a low acid food. Firstly, inactivation curves of pathogens were obtained at 200 to 400 MPa at 40ºC in peptone water and carrot juice. First-order and Weibull models were fitted and Weibull model described the inactivation curves of both pathogens more accurately than first-order model, revealing that food systems could exhibit eithe...
Nutritional and cultural parameters influencing antidipteran delta endotoxin production
ÖZKAN, MELEK; Dilek, Filiz Bengü; Yetiş, Ülkü; Özcengiz, Gülay (Elsevier BV, 2003-01-01)
In this study, various nutritional and cultural parameters influencing diptera-specific delta-endotoxin synthesis by Bacillus thuringiensis subsp. israelensis HD500 were investigated. Of various inorganic nitrogen sources, the highest yields of Cry11Aa and Cry4Ba proteins were obtained on (NH4)(2)HPO4. Among carbon sources, inulin, dextrin, maltose, lactose, sucrose, whey and glycerol were all stimulatory, while glucose, starch and molasses were suppressive. High concentrations of inorganic phosphate (50 to...
Trehalose, glycogen and ethanol metabolism in the gcr1 mutant of Saccharomyces cerevisiae.
Şeker, Tamay (Springer Science and Business Media LLC, 2003-01-01)
Since Gcr1p is pivotal in controlling the transcription of glycolytic enzymes and trehalose metabolism seems to be one of the control points of glycolysis, we examined trehalose and glycogen synthesis in response to 2 % glucose pulse during batch growth ingcr1 (glucose regulation-1) mutant lacking fully functional glycolytic pathway and in the wild-type strain. An increase in both trehalose and glycogen stores was observed 1 and 2 h after the pulse followed by a steady decrease in both the wild-type and the...
Regulation of crystal protein biosynthesis by Bacillus thuringiensis: I. Effects of mineral elements and pH
ICGEN, Y; Icgen, BÜLENT; Özcengiz, Gülay (Elsevier BV, 2002-11-01)
Crystal protein synthesis by a local isolate of Bacillus thuringiensis was monitored and compared in association with growth and sporulation in media differing in mineral element content. Mg and Cu were the most important metals for the biosynthesis of 135 kDa and 65 kDa toxin components in that the former was essential and the latter was greatly stimulatory at 10(-6) to 10(-7) M concentration. Also the inclusion of Mn favored toxin production at concentrations ranging from 3 x 10(-4) to 10(-5) M. The omiss...
Citation Formats
N. Ertugay, H. Hamamci, and A. Bayındırlı, “Fed-batch cultivation of bakers’ yeast: Effect of nutrient depletion and heat stress on cell composition,” FOLIA MICROBIOLOGICA, pp. 214–218, 1997, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/48547.