Cultivation, chemostatic

Yeast showed an accumulation of PolyP3 following PolyP hydrolysis induced by amines and basic amino acids (Greenfeld et al., 1987). The degradation of NMR-observable , probably vacuolar, PolyP to short-chain polymers in the cells of Chemostat-cultivated S. cerevisiae contributed to neutralizing the added alkalinity (Castro et al., 1995, 1999). In contrast, when the vacuolar vphl-1 mutant, lacking NMR-visible PolyP, was subjected to alkalinization, the absence of a vacuolar source of phosphate slowed re-acidification (Castro et al., 1999). Anaerobiosis resulted in the complete hydrolysis of PolyP to P (Castro etal, 1995). 

C. D. Castro, A. J. Meehan, A. P. Koretsky and M. M. Domach (1995). In situ 31P nuclear magnetic resonance for observation of polyphosphate and catabolite responses of chemostat-cultivated Saccharomyces cerevisiae after alkalinization. Appl. Environ. Microbiol., 61, 4448-4453. 

Fig. 5 Tailor-made mcl-PHA in chemostat cultivation (Z)=0.1 h" C/N= 15 gg" in the medium feed) of P. putida GPol with 10-undecenoate (fixed substrate feed at 10 mol% of total carbon feed), and variable amounts of 5-phenyl valerate and octanoate. a Composition of mcl-PHA as a function of the carbon feed composition, b glass-transition temperature of polymers with various contents of saturated and aromatic monomers. Letters indicate identical polymers in a and b. F indicates the glass-transition temperature of the homopolymer poly(3-hydroxyphenylvalerate) described by Fritzsche et al. (1990b). (Redrawn from Hartmann et al. 2004)...

The unlimited growth-related type of poly(3HB) synthesis is most suited to one-stage continuous cultivation. This can be performed in a chemostat with carbon substrate limitation. The poly(3HB) content of the cells can be further... 

Batch, fed-batch and perfusion processes are commonly used in large-scale cultivation of mammalian cells. Chemostat cultures are a valuable tool for cell physiology studies but not a serious contender as a production process [3]. 

Fermentation and alternative production techniques, such as roller bottles, can be carried out in four different ways. They are (1) batch process, (2) fed-batch process, (3) chemostat process, and (4) perfusion process. Batch and fed-batch processes require termination of cell growth while chemostat and perfusion processes allow continuous cell cultivation. 

Determine the value of the dilution rate where the maximum cell productivity is obtained in chemostat continuous cultivation. 

You are going to cultivate yeast, Saccharomyces cerevisiae, by using a 10 m -fermenter your company already owns. You want to find out the amount of ethanol the fermenter can produce. Therefore, a chemostat study was carried out and the Monod kinetic parameters for the microorganism grown in the glucose medium at 30°C, pH 4.8, were found to be Ks = 0.0025 g/L and /imax = 0.25 h-1. The ethanol yield (YP/S) is 0.44 (g/g) and cell yield (Yx/S) is 0.019 (g/g). The inlet substrate concentration is 50 g/L-... 

The following cultivation modes have been described for production of MAbs in in vitro large-scale systems batch, fed-batch, chemostat and perfusion (Reuveny Lazar, 1989). Batch and fed-batch processes are the most common methods. More demanding are chemostat and perfusion modes, which allow a continuous production of MAbs. All methods are applicable in homogeneous and, with the exception of chemostat, non-homogeneous systems. 

Tovey MG (1980) The cultivation of animal cells in the chemostat applications to the study of tumour cell multiplication. Advances in Cancer Research 33 1-37. 

Fascetti, E. and Todini, O. (1995). Rhodobacter sphaeroides RV cultivation and hydrogen production in a one- and two-stage chemostat. Appl. Microbiol. Biotechnol. 44, 300-305. 

Continuous H2 production by A. variabilis PK84 under outdoor, aerobic conditions was shown by the next experiment. The cells growing in batch culture in the PhBR were shifted to the chemostat mode of cultivation at dilution rate D=0.02 h 1 (Fig. 2a). The H2 production rate of 25 to 35 ml h 1 PhBR 1 was sustainable through out the experimental period of 36 days excepting 2 or 3 dull days. During these days it could be noticed a correlation between the Chi a concentration and density of cells and H2 production (Fig. 2b). 

The continuous operations of Table 2 are elaborated in Table 3 as three types of operations. In a chemostat without feedback control, the feed medium containing all the nutrients is continuously fed at a constant rate (dilution rate) and the cultured broth is simultaneously removed from the fermenter at the same rate. A typical chemostat is shown in Fig. 1. The chemostat is quite useful in the optimization of media formulation and to investigate the physiological state of the microorganism. A turbidostat with feedback control is a continuous process to maintain the cell concentration at a constant level by controlling the medium feeding rate. A nutristat with feedback control is a cultivation technique to maintain a nutrient concentration at a constant level. A phauxostat is an extended nutristat which maintains the pH value of the medium in the fermenter at a preset value. 

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