Yeasts cultivation

Frohlich, S., Lotz, M., Korte, T., Lilbbert, A., Schilgerl, K., Seekamp, M., Characterization of a Pilot Plant Airlift Tower Loop Bioreactor II. Evaluation of Global Mixing Properties of the Gas Phase During Yeast Cultivation, Biotechnol. Bioeng., 37 910 (1991a)... 

The dynamic behavior of the cell metabolism initiated by different external effects (addition of substrates or inhibiting reagents) can be followed via this instantaneous method. These effects can be used to control the overall process and optimize the bioprocess. Meyer and Beyeler [50] developed a control system for a continuous yeast cultivation process. Here the increase up to the optimal dilution rate was controlled via fluorescence monitoring. The dilution rate was only increased when no negative effect on the metabolic state of the cells was observed. During the cultivation of Candida utilis the fluorescence signal was used for the addition of substrate ethanol. The addition was started when... 

Fig. 6. Prediction of the ethanol concentration in a yeast cultivation. The open circles show the predicted ethanol concentration using a three layer ANN. The filled circles show off-line analyses of ethanol using a reference method (from [29] with permission from Elsevier)...

The methodology was applied to fed-batch baker s yeast production on a 200-m3 scale [33]. The typical phases in a baker s yeast cultivation were visualized including lag phase, formation and consumption of ethanol and increase and decrease of cell mass. Fusion of signals from external sensors for volume, aeration flow rate and dissolved ethanol resulted in different character of the trajectory in the PCA but with the same principal information. 

G. I. Vorob eva, S. P. Grigor eva, I. S. Kulaev and G. N. Maksimova (1973). Studies on the regularities of phosphate metabolism in yeasts cultivated on hydrocarbons, in Proceedings of the 3rd International Special Symposium on Yeasts, Otaniemi, Helsinki, Finland, p. 51. 

Rychtera, M., Barta, J., Fiecter, A., and Einsele, A. A. (1977). Several aspects of the yeast cultivation on sulphite waste liquors and synthetic ethanol. Process Biochem. 12(2), 26-30. Rydholm, S. A. (1965). "Pulping Processes." Wiley (Interscience), New York. 

Hoffstetter-Khun, S., T. Rosier, M. Ehrat, and H. M. Widmer, Characterization of yeast cultivations by steric field-flow fractionation, Anal. Biochem. 2 300-308 (1992). 

The substrate specificity of AOD from different microbial sources has been studied in detail. Yeasts cultivated on methanol produce large amounts of AOD together with catalase. This AOD has a high activity towards methanol. Ethanol is oxdized more rapidly only by AOD from Basidiomycetes. AOD also reacts with other aliphatic alcohols, mercap-tans, and formaldehyde. Acetone, isopropanol, lactate, and other hy-droxyacids do not react. Because of the high catalase content of the... 

B. Horstkotte, E. Werner, A.K. Seresht, G. Cornelissen, O. Elsholz, V. Cerda, R. Luttmann, Sequential injection analyzer for glycerol monitoring in yeast cultivation medium, Talanta 71 (2007) 941. 

Temperatures around 30 C have been utilized for xylitol production yeasts cultivated in synthetic medium or in hemicellulosic hydrolysates produced from... 

Merchuk JC, Asenjo JA. 1995. The Monod equation and mass transfer. Biotechnol Bioeng 45(l) 91-94. Mikola M, Seto J, AmanuUah A. 2007. Evaluation of a novel Wave Bioreactor ceUbag for aerobic yeast cultivation. Bioprocess Biosyst Eng 30 231-241. 

Duarte, S.H., Maugeri, F., 2014. Prediction of quality properties for biodiesel production by oleaginous yeast cultivated in pure and raw glycerol chemical engineering transactions. Chemical Engineering Transactions 37, 463—468. 

Wine. The earliest known wines were made in Iran about 5400—5000 BC (25). The species of grape used is unknown and may have been either the wild grape Fitis viniferus sylvestris or a cultivated precursor of the modem wine grape V. viniferus viniferus. The source of the yeast used, and the procedures used are completely unknown. In modem times, grapes (about 21—23% sugar) are pressed the liquid must is either separated and allowed to settle for 1—2 days (for white wines) before inoculation with yeast, or the whole mass is dkectly inoculated with yeast (for red wines). In either case, while the initial fermentation takes place, the carbon dioxide formed by fermentation excludes ak and prevents oxidation. White wines are transferred to a second fermentor (racked) near the end of fermentation and kept isolated from the ak while solids, including yeast, settle out, a process that requkes about six... 

A. tubingensis strain NW756 was cultivated for 55 h at 30 C in minimal medium according to Pontecorvo et al [1] supplemented with yeast extract (2g/l) and 10 g/1 endo-PG II digested polygalacturonic acid (PGA). Complete hydrolysis of PGA by endo-PG II resulted in a mixture of mono, di and trigalacturonate [2]. Four subsequent colunm chromatographic steps were used for purification of the enzyme for which the data are summarized in Table 1. 

When Rhizopus sp. 26R was cultivated in the solid substrates without addition of rice bran but composed of only wheat bran and rice husk at the ratio of 18 2. The pectinase activity from the culture was approx. 25-35 unit/ml within 2 days and the production remained constant for 4 days (Figure 3). One gram of raw starch from cassava tuber, 1 g of pectin or 0.5 g of yeast extract was added to the solid substrates in order to induce higher activity of the enzsrme. The results showed that either 1 g raw cassava starch or 1 g pectin that was added to the 20 g solid substrates increased the enzyme activity to 1.7 and 2.4 times, respectively (Figure 3). The production of pectinase in soHd substrates with wheat bran and rice husk could be enhanced with the addition of raw cassava starch and pectin. 

Candida boidinii is a further yeast producer of pectic enzymes complex. The production is induced by the presence of pectin as a C-source in the medium the primary methabolic path is the utilization of methanol and the secondary the utilization of pectate chains. The pectic enzymes were bound on the cell walls or released on the cultivation medium. The main enzyme of pectic complex, polygalacturonase, was briefly characterized and the possibility to influence the production of its multiple forms discussed. 

The cultivation of this yeast strain on pectin medium showed optimal grow conditions. The behaviour of this strain was compared with that of four strains of Candida boidinii from the Culture Collection of Yeasts. The grow curves of all strains on pectin medium showed marked plateau suggesting the presence of two existing C-sources in the pectin medium, requiring two different metabolic paths (Fig. 1). 

The poor activities of pectic enzymes in the cultivation medium led us to prove the cell cytosole and the cell walls for these activities. The cytosole contains only traces of polygalacturonase activity, but the suspension of cell walls established the activity which seems to be widely sufficient for yeast growth and development. The characterization of this cell wall bound enzymes will be the object of our next studies. 

A yeast is cultivated in a CSTR with partial recycle of the product. Effluent from the reactor has concentrations Cx and Cs and goes to a separator where a product stream, F, has concentrations 0.3CX and Cs. The recycle stream, R, likewise has concentration Cs and a material balance on X as Recycle = (F+R)CX -0.3FCX = (0.7F+R)CX = RCxr (1)... 

Aiba, S., Moritz, V., Someya, J. and Haung, K. L. (1969). Cultivation of yeast cells by using n-alkanes as the sole carbon source. I. Batch culture, J. Ferm. Technol., 47, 203-210. 

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