Yeast strains temperature effects

Besides addition of heme, the influence of culture temperature on heterologous production of peroxidases has also been reported. For example, lowering the culture temperature from 28 to 19°C enhanced the level of active versatile peroxidase of P. eryngii 5.8-fold and reduced the effective proteolytic activity of the A. nidulans host strain by 2-fold. In this way, a maximum peroxidase activity of 466 U/L was reached [42]. Efficient heterologous production of peroxidases is not always dependent on the availability of heme. The heterologous production of Arthromyces ramosus peroxidase (ARP) has been analyzed in A. awamori under the control of the inducible endoxylanase promoter. Secretion of active ARP was achieved at up to 800 mg/L in shake flask cultures without addition of hemin [43]. This represents a 1,600-fold increase in production compared to ARP production in S. cerevisiae and 38-fold increase compared to ARP production in P. pastoris (see Sect. 12.2). These observations support that several filamentous fungi are more effective secretors of proteins than yeast strains like S. cerevisiae and P. pastoris. Also for... 

Yeast strain, and nutrient status of the must and fermentation conditions, many of which affect growth or induce physiological stress, modulate the accumulation of acetic and other fatty acids in wine. Reported factors include must sugar concentration, nutrient balance, inoculum level, fermentation temperature, pH and aeration (Delfini and Costa 1993 Henschke and Jiranek 1993 Shimazu and Watanabe 1981). The effects of osmotic stress, as induced by sugar concentration, on acetic acid production are discussed in Sect. 8D.3.2. 

With regards to fusel alcohol production, Kunkee and Goswell (5) noted that while yeast strain appeared to have an effect on fusel alcohol production, other factors, notably must composition, appeared to have equally important influences. For example. Berry and Watson (29) reported that added nitrogen and carbohydrates can stimulate higher alcohol production, as can increased pH (59). Various processing parameters can also affect fusel alcohol production, including agitation, aeration, and temperature (29,59). 

Tromp, A. 1984. The effect of yeast strain, grape solids, nitrogen and temperature on fermentation rate and wine quality. S. Afr. J. Enol. Vitic. 5, 1-6. 

All of these factors, individually or more often in combination with one another, permit the definition of the requirements of an acceptable brewer s yeast strain (Stewart Russell, 2009). To achieve beer of high quality, not only the yeast must be effective in receiving the required nutrients from the growth/fermentation medium (the wort), able to tolerate the prevailing environmental conditions (e.g. osmotic, temperature and ethanol tolerance) and impart the desired flavour to the beer, but the microorganisms themselves must be effectively removed from the fermented wort by flocculation, centrifugation and/or filtration after they have fulfilled their metabolic role. 

Storage temperature (Figure 2.5) has a direct influence on the rate and extent of glycogen utilization, as might be expected, considering the effect that temperature has on metabolic rates in general. Although strain dependent, of particular interest is the fact that within 48h, the yeast stored semi-aerobically at 15°C has only 15% of the... 

Lethal effects of a high fermentation temperature are often thought to result from the effect of temperature alone. However, inhibition is also the result of intracellular accumulations of ethanol. Temperature tolerance of yeast varies with species and strain and reflects intrinsic and extrinsic properties of the growth medium. Generally, yeast viability in alcoholic media subsides at temperatures near 35°C (95°F). 

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