Specific growth phase

You may for example have suggested that the supply of other nutrients, such as ammonia and O2, may be adjusted to respond to the different needs of growth and penicillin production. You may also have suggested that precursors of specific penicillins, such as P-phenylacetic add, may be added after the growth phase is complete. You may have also considered altering physical parameters such as pH and temperature. 

Table 3.1 shows the kinetic parameters for cell growth, rate models with or without inhibition and mass transfer coefficient calculation at various acetate concentrations in the culture media. The Monod constant value, KM, in the liquid phase depends on some parameters such as temperature, initial concentration of the carbon source, presence of trace metals, vitamin B solution, light intensity and agitation speeds. The initial acetate concentrations in the liquid phase reflected the value of the Monod constants, Kp and Kp. The average value for maximum specific growth rate (/xm) was 0.01 h. The value... 

The effect of substrate concentration on specific growth rate (/i) in a batch culture is related to the time and p,max the relation is known as the Monod rate equation. The cell density (pcell) increases linearly in the exponential phase. When substrate (S) is depleted, the specific growth rate (/a) decreases. The Monod equation is described in the following equation ... 

Suitable rate expressions for rs and rx and the specification of the initial conditions would complete the batch fermenter model, which describes the exponential and limiting growth phases but not the lag phase. 

The Kq saturation coefficient of oxygen in the Monod-type kinetic equation is an important parameter, too. Its value strongly influences the specific growth rate, especially when the value of oxygen concentration is of the same order of magnitude as or lower than the Kq value. Its effect is illustrated in Fig. 10 in the presence of a dispersed organic phase, e = 0.2. The increasing value of Kq (Kq was chosen to be equal to 0.64 x 10 0.16 x 10 and 0.016 x 10 kg m ) has a... 

Yeast cells grow in the exponential phase. The cell mass concentrations are given in Table 4.4. Calculate the specific growth rate,... 

Figure 4.2 Determination of a specific growth rate in the exponential growth phase.

Assign the exponential growth phase, and evaluate the maximum specific growth rate. How does the specific growth rate differ from those off. coli and yeast cells in Problems 4.2 and 4.3 ... 

The use of an immobilized biofilm system is recommended, since the oxidation products often are only slowly biodegradable. Biomass, especially slow growing microorganisms, can efficiently be kept in the system using support material. This is especially important in continuously operated systems where the liquid phase is completely mixed. In such a system suspended biomass would be washed out when the hydraulic retention time is less than or equal to the population doubling time (i. e. the reciprocal of the specific growth rate Grady, 1985). In several studies materials such as polyurethane foams (Moerman et al., 1994 Jochimsen, 1997) or quartz sand particles (Stem etal., 1995 and 1996 Heinzle et al, 1995 Saupe and Wiesmann, 1998) have been used for immobilization. 

The time frame of antisense ODN introduction to injured vessel may play an important role in the prevention of restenosis. Schmidt et al. (57) showed that rat carotid artery SMC proliferation begins one to two days after balloon catheter-induced injury, and entry of cells into the growth phase was completed within three days of injury. At the same time, minimally modified b-FGF-specific antisense ODN exerted its antiproliferative activity within this time frame. This strategy has also been successfully applied in the inhibition of various targets, such as c-cbl and c-src (58), HSV-1 (59), and c-myc (47). 

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