Yeasts culture temperature

Proper, timely addition of SO 2 Temperature control during fermentation Pure yeast cultures... 

The enologist then processes the grapes, utilizing the most sanitary equipment, fermenting the juice into wine under controlled temperature conditions. He uses pure yeast culture in fermentation and follows the fermentation process daily. 

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... 

A similar type of assay was done with bacterial and yeast cultures treated similarly. Cultures were washed by centrifugation in 0.1 M phosphate buffer (pH = 7.0) and resuspended to an OD580 = 0.3. Attachment after 30 min at room temperature to plastic and Cell-Tak-coated plastic was evaluated qualitatively by microscopic visualization. 

On the other hand, contact with wood casks is necessary for the aroma profile of the wines obtained with selected strains to resemble that of commercial wines. In this sense, wine could be aged with selected strains of yeast in the wood casks themselves. However, maintaining the conditions required by the selected yeast cultures (mainly an appropriate temperature and the absence of contamination during the process) on an industrial scale is rather difficult. Therefore, it is reasonable to think that wine could be aged in two steps. 

The tolerance of yeast cultures and individual cells to stress factors such as osmotic pressure, ethanol, temperature, desiccation and mechanical stress ... 

If a cropped yeast culture is not stored properly, cell consistency will suffer, and it will adversely affect fermentation and beer quality. After cropping, the yeast is stored in a room that is conveniently sanitized and contains a plentiful supply of sterile water and a separate filtered air supply with positive pressure to prevent the entry of contaminants at a temperature of 0°C. Alternatively, insulated tanks in a dehumidified room can be used. In addition, off the shelf yeast storage facilities are available at various working capacities. 

To improve production conditions, film growth can be accelerated by inoculation with a film-producing yeast culture and by leaving head space when filling the barrel, instead of waiting for it to occur spontaneously by evaporation. Maintaining a low temperature (12-13°C) also limits bacterial spoilage. 

Fig. 8.1 Growth behavior of Acetobacter pasteurianus NBRC3283. Cells were cultured in YP basal medium (1 % yeast extract, 1 % polypepton) supplemented with two kinds of carbon sources, respectively. The culturing temperature was 30 °C with shaking at 121 rpm. (a) 170 mM ethanol was supplemented as a carbon source. Solid line OD at 660 nm broken line concentration of acetic acid in culture medium, (b) 170 mM glycerol was supplemented as a carbon source...

Agar, which is low in metabolizable or inhibitory substances, debris, and thermoduric spores, is ideal for the propagation and pure culture of yeasts, molds, and bacteria. Agar also meets the other requirements of ready solubiUty, good gel firmness and clarity, and a gelation temperature of 35—40°C and a gel melting temperature of 75—85°C. A clarified and purified form of the bacterial polysaccharide, geUan gum, is the only known satisfactory substitute. 

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