Biomass growth rate

The idea behind the experiment is to let the biomass growth rate change from zero to its maximum value. By adding a known amount of substrate under controlled conditions, the interpretation of the OUR response can be described by the model concept (cf. Table 7.1) and the four central process parameters can be determined. The following two conditions are important for a successful outcome of the experiment ... 

The rates of uptake of substrate and oxygen are related to the biomass growth rate by appropriate yield constants ... 

In this example, it is easy to see that, the dynamics of C is quite independent of the kinetics p, which gives a specific solution to the well known problem of the biomass growth rate ignorance in the bioprocess [66]. It is also verified that the convergence rate cannot be tuned because it depends exclusively on the value of the dilution rate. Indeed, Bastin and Dochain [6] have shown that a condition to guarantee the convergence of the observer is that the dilution rate D must be a persisting input, i.e., that there are two positive constants Cl and C2 such as, at every time t ... 

The oscillatory behavior of product-inhibited cultures cannot simply be described by a common inhibition term in the equation for the biomass growth. A better description must include an indirect or delayed effect of the product ethanol on the biomass growth rate as indicated in experiments. The decay rate pmaa was introduced to account for the accumulation of the inhibitory product pyruvic acid. Other more mechanistic, structured models can be formed that relate to the internal key-compound e. In these, the inhibitory action of ethanol is accounted for in the inhibition of the key-compound e formation. Mathematically, however, these two model descriptions are equivalent, except that the key-compound e is washed out as a part of the biomass in continuous cultures and the rate constant //ma55 does not vary. Our proposed indirect inhibition model provides a good qualitative description of the experimental results shown in Figure 7.25. 

Fig. 8. Effect of inoculum size on biomass growth rate in bioreactor culture for 32 d.

Gessner, M. O. Newell, S. Y. (2002). Biomass, growth rate, and production of filamentous fungi in plant litter. In Manual of Environmental Microbiology, 2nd edn, ed. 

Monod-Type Empirical Kinetics Many bioreactions show increased biomass growth rate with increasing substrate concentration at low substrate concentration for the limiting substrate, but no effect of substrate concentration at high concentrations. This behavior can be represented by the Monod equation (7-92). Additional variations on the Monod equation are briefly illustrated below. For two essential substrates the Monod equation can be modified as... 

Once all of the controllable factors are in place, it is critical to select the proper bacterial combination(s) that enables the appropriate rate of biomass growth and enzyme production. For instance, the primary step in trichloroethylene bioremediation is the production of oxygenases, such as toluene dioxygenase (tod). However, oxidation of trichloroethylene generates intermediates that inactivate the tod enzyme and can even be toxic to the cells themselves, i.e., catabolite repression. Thus, the biomass growth rate and... 

Contrary to Section 3.3, where we addressed the equivalent transport problem, ballistic photons here are in the minority, except close to = 0, for 0 G [0, r/2]. It is possible to take into account all the ballistic photons in our calculations (Eqs. (75) and (76)) because the mesoscopic solution for is obtained easily, even in the present case, with Lambertian emission and reflection 2Lt z = E. Nonetheless, except for the term that we used in Eq. (84), their contribution to the boundary conditions is negligible for most photobioreactor configurations during operation close to the optimum biomass growth rate. 

Figure 29 The volumetric biomass growth rate < > and its sensitivity parameters...

Finally, if necessary, the mean volumetric biomass growth rate in the photobioreactor < R > is easily obtained by means of a spatial integral of the specific rate of net oxygen production < J02 > and again by means of... 

Now, the proposed kinetic coupling law (Eq. (163)), already used for example by Takache et al. (2012) for C. reinhardtii cultivation in a simple rectangular photobioreactor, is discussed in the text later as illustration of the whole methodology developed throughout this chapter, especially the use of the integral Monte Carlo formulation for easy calculation of the radiation field, volumetric biomass growth rate < Rx>, standard deviation of the results, and all the desired types of sensitivity (with the same calculation time). 

In order to analyze a biological process with a biomass, the starting point is the knowledge of the nutrient consumption rate, of the product generation rate and, especially, of the biomass growth rate. These different rates are related to each other through the stoichiometry of the reactions that take place inside the cells and, in a simple approach, they can be expressed by means of yield factors. Since the biomass growth is related to cell multiplication, its rate (per unit volume, for instance) can be set proportional to the biomass concentration X ... 

A two-stage continuous culture system where a phase-wise optimization was carried out which maximizes the residual biomass growth rate in the first stage followed by a PHB production rate in the second stage was reported by Lee et al. Maximmn PHB productivity of 2.86 g/L/h was obtained in this process. 

X represents the biomass, P the product, and 5 the glucose (or substrate) concentration (kg/m ). For a clear insight into the first equation in particular it is useful to remember that p is the specific biomass growth rate in h (see Section... 

Van Impe and Bastin (1995) describe the substrate to biomass conversion by the Contois equation (biomass growth rate //) ... 

If one or more of the inputs is present in less than optimum amount, then the respiratory rate and efficiency, and hence the formation of structural biomass (growth rate), will be reduced to the rate determined by the rate of acquisition of... 

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