Medium composition

Nitrate was shown to be limiting in the air lift cultures carried out with a modified CHU 13 medium (777). Progressive increase in nitrate initial concentration thus results in a more extended exponential phase, until another nutrient becomes in turn limiting. This adjustment of the nitrate supply allows for a substantial increase in final biomass and hydrocarbon production in batch cultures, ca 75 and 60%, respectively. 

Since phosphate is not limiting, higher initial concentrations do not cause any changes in the growth curve or in the final biomass from batch cultures of B. braunii 104). However the lipid content of algae is known to be influenced by the P/N ratio in the growth medium and the hydrocarbon production of B. braunii is somewhat improved ca 10%) following a twofold increase in phosphate supply 104). 

No adverse effect of salinity up to that of seawater was observed on B. braunii growth and addition of 6% NaCl in the medium resulted in a substantial increase of the level of total lipids ca 50% of biomass instead of ca 35%) (772). 

Although, in the production of CGTase, the ability of strains to produce enzyme is the determinant factor, the effect of the fermentation process conditions on the production of enzymes is also crudal. Fermentation conditions include not only the composition of the medium, but also temperature, pH, aeration rate, agitation and other factors, and are of interaction and mutual restraint, with appropriate coordination among the said conditions. Therefore, on condition that the production strain is appropriately chosen, the control of the fermentation process is a key factor for the final output. 

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VARIATION OF SOLVENT ISOTOPE EFFECT WITH MEDIUM COMPOSITION IN REACTION... 

Medium D Perchloric acid in acetic acid, medium composition not quoted687 rate coefficients obtained by extrapolation from values at other temperatures. 

The classical Chinese method consists of inoculating steamed rice grains spread on big trays with a strain of Monascus anka and incubating in an aerated and temperature-controlled room for 20 days. In these types of cultures, moisture content, oxygen, and carbon dioxide levels in the gas environment, as well as cereal medium composition, are the most important parameters to conhol. 

Effect of Medium Composition on Metal Speciation and Toxicity. 417... 

Expt. Medium composition Electrolysis time (h) Volume of CO produced (ml) Coulombs consumed Average current efficiency (%)c... 

Initial scale-up of microbial biotransformation is conveniently run with multiple flasks without extensive reaction optimization. A typical flask fermentation is performed at 28 °C, 250 rpm with 100 mL culture in a 500 mL Erlenmeyer flask, although other settings will work fine too. Three parameters need to be investigated before scale-up the time for adding the substrate, the optimal substrate concentration and the time course of product formation. Optimization of other factors, such as medium composition and pH, growing cells versus resting cells [74], is helpful, if the timeline allows and if there is a sufficient amount of the substrate to support the screening. 

Furthermore, via optimization of the medium composition and fermentation conditions, the maximum cell density was increased by twofold, yielding a final titer of 1.1 g L 1 of 6dEB [60]. In another approach, Murli et al. [61] evaluated the three pathways of (2,S )-methylmalonyl-CoA biosynthesis (1) Streptomyces coelicolor PCC, (2) Propionibacteria shermanii MCM/... 

The medium composition used in the fed-batch process was optimized, resulting in cell densities near 100 g l-1. By using an exponential feed rate resulting in a growth rate of 0.05 h-1, a maximum biomass concentration of 112 g 1 1 was attained, with a biomass productivity of 1.8 g 1 1 h. The poly(3HAMCL) productivity however was low, 0.34 g 1 1 h, caused by a steady decrease of the poly(3HAMCL) content during the last part of the fermentation [51]. When this optimized medium composition was used in the continuous culture system described above, a maximum biomass concentration of 18 g 1 1 was reached. The PHA content however remained low at approximately 10% [51]. It is still unclear what causes these low PHA contents. 

Table 2 Recommended Dissolution Medium Composition and Volume for Rotating Basket or Rotating Paddle Apparatus...

We optimized the cultivation protocol with respect to aqueous medium composition, organic phase, and phase ratio (the ratio of the volume of the organic phase to the total liquid volume). The best system consists of a defined mineral medium, with glucose as the carbon source and diethylhexylphthalate as the organic phase at a phase ratio of 0.5. The organic phase contained 2 vol % styrene and 1 vol % of octane, which we added as an inducer for gene expression. 

Other independent variables (changes in temperature or medium composition) should produce effects analogous to pressure and therefore induce phase changes and shifts in association equilibria. Combination of these different variables could be used to investigate protein-subunit interactions and conformational changes, to determine the fundamental physical-chemical parameters of these changes. 

If complexity is suspected from the kinetic behavior, the effect of products and of possible impurities and the occurrence of side reactions should be considered. Later we shall see that medium composition (Sec. 2.9), temperature and pressure (Sec. 2.3) are other important parameters that affect rate. The rate law incorporating these effects is obtained by further experiments of the type indicated in step 3. 

When some other factor also enters into the tautomerization equilibrium, such as a variable medium, then tautomerism may be observable over a certain range of medium compositions. Examples of this kind of behaviour may be found in concentrated aqueous acids, where varying degrees of hydration of the two types of cation can lead to a dependence of the tautomeric equilibrium upon the activity of water, as discussed in the preceding section. This happens in the tautomerization of amide and phenol (or anisole) cations and further discussion of this phenomenon will be deferred until later (see pages 333 and 372). 

Thengane SR, Kulkami DK, Shrikhande VA, Joshi SP, Sonawane KB, Krishnamurthy KV. (2003) Influence of medium composition on callus induction and camptothecin(s) accumulation in Nothapodytes foetida. Plant Cell Tissue Organ Cult 72 247-251. 

Figure 6.3 Effect of fermentation medium composition on the rate of ethanol production from glucose using extruded yeast pellets. Reproduced from Hayes (1998) with permission.

The special treatment of cell cultures for increasing the yield of alkaloids can be linked to improvements in medium composition, the addition of enzymes and alkaloid precursors, the addihon of the so-called elicitors and changes in environmental factors. The medium can be improved by changes in the relahons between its components sucrose and carbon components, nitrogen, phosphorus... 

Adams SL, Zhang T, Rawson DM (2005) The effect of external medium composition on membrane water permeability of zebrafish (Danio rerio) embryos. Theriogenology 64 1591-1602... 

Assumption 2 was later shown to be of very limited applicability (83CJC2225). Clearly, the response of the various ys to changing medium composition is strongly structure dependent. Recognition of this fact led to the development of a number of empirical acidity and basicity functions (70MI4). Representative examples are as follows. 

The value of does not depend on the medium composition, and in principle this is the only equilibrium constant needed. However, since activities of substrates and products are often hard to get at, concentration-based equilibrium constants are often used instead. Concentrations can, for example, be expressed as molar ratios (xA, etc.). For each substrate or product, mole ratio and activity can be interconverted using activity coefficients (yA, etc), where aA = yA xA. 

Finally, the purity-related performance of the enzyme preparation would appear to be a constant throughout a series of measurements. This, however, may not be the case when several enzyme species are present and different activities are expressed as a function of the medium composition [100]. Although it would appear that this source of error is abolished by the present-day availability of highly pure enzyme preparations (but see also [101, 102]), the intrinsic properties of i.e. Upases may lead to different E-values as a result of interfacial activation [103] and the conformation of the lid structure of lipases [56]. 

Despite the large number of reports of successful efforts to increase the E-value of enzymes by managing the medium composition, proper understanding of the... 

An expert system is a computer program to reproduce a problem-solving manner according to an expert s knowledge and inference procedures in a computer system. Expert systems have been used for fault diagnosis in bioprocess operations, the improvement of medium composition, and the optimization of culture conditions, since it can handle a large amount of information and data concerning bioprocess operation and optimization [13]. 

It is well known that there are numerous factors that influence the gel collapse (charge density, topological structure of a network, medium composition, etc.). The same factors are effective in the case under study as well (see... 

The exact fatty acid composition depends not only on growth temperature but on growth stage and growth medium composition. 

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