During exponential growth

Xanthan is synthesised during exponential growth of the culture, whereas sucdnoglycan is synthesised after growth has ceased (biomass constant). 

Put another way, during exponential growth the microbial population will double in number for every time interval, t = (In 2)1 fx. 

For every cell which enters mitosis at the end of the cell cycle two will begin the next cycle. This means that the distribution of cells around the cycle is not uniform, but that there is a preponderance of young cells during exponential growth. 

Bodies. The fraction of cells containing inclusion bodies was constant during exponential growth for a single inoculum, but depended strongly on the density... 

Figure 6. Influence of inoculum density on the fraction of cells containing inclusion bodies during exponential growth (10 - 10 CFU/mL).

Figure 7. Relationship between the fraction of cells containing inclusions during exponential growth and the relative prochymosin content of the cells. Inoculum density 0.14 CFU/mL (a) inoculum density 140 CFU/mL ( ).

The fraction of cells which contained visible inclusion bodies during exponential growth was constant but depended on the inoculum size. Larger inocula yielded cultures with significantly fewer inclusion body containing cells. The amount of prochymosin correlated to the number of ceUs showing visible inclusions. 

The observations made in this study on inclusion body formation are explained by a pole age model of ceU growth. The constant fraction of cells with inclusion b ies during exponential growth is a consequence of segmentation of ceU cytoplasmic regions by the nuclear material in the cell, and the fact that inclusion bodies are discrete objects which cannot migrate from one end of the... 

Induction of cells during exponential growth (1-3 OD600/ mL) will increase expression. scFv expression can also be enhanced by having 0.1-0.2% dextrose in the induction media. Often cells can be simply diluted tenfold from the SD-CAA growth culture. For example 9mL of SG/R-CAA induction media can be directly inoculated with 1 mL of SD-CAA culture. 

Eukaryotic cell cycle - The processes by which cells divide and DNA is replicated (see here) are somewhat more complicated in eukaryotes than in prokaryotes. DNA replication in bacteria is an almost continuous process, at least during exponential growth. The somatic cells of eukaryotes, on the other hand, typically divide much less frequently, and some, in certain types of mature tissue, do not divide at all. Eukaryotic cells that are dividing in growing tissues exhibit a well-defined cell cycle, which is almost always separated into several distinct phases, as shown in Figure 28.14, Figure 28.15, and Figure 28.16. 

This was possible to detect because the monoculture of Thalassiosira rotula employed showed partly synchronized cell divisions during exponential growth. Brockmann et al. [137] carried out combined measurements of dissolved amino acids and carbohydrates. Glucose and lysine occurred in highest concentrations. Mague et al., [22] found that extracellular production of free amino acids counted for 7.1% of the of the total extracellular C released in an exponentially growing culture of S. costatum Myklestad et al., [26] measured 10.7% for C. affinis or 3.6% when calculated as percent of total incorporated cell N. In contrast to this Admiraal et al., [139] found that none of three benthic diatoms released more than 0.1 % of the cellular N as free amino acids and concluded that benthic diatoms may act as net consumers of amino acids. Several authors did measure both intracellular and extracellular concentrations of many amino acids [22 140 -142]. The clear difference in relative composition of intracellular and extracellular fractions as pointed out by the first mentioned of these authors, show that the released pool is not just a portion of the intact cells content. 

Carlucci and Bowes [29] showed that vitamin production in phytoplankton algae was attributed to release during exponential growth and upon cell death and lysis in old cultures. Vitamin utilization was readily observed in cultures of two species S. costatum produced utilizable biotin for Amphidinium carterae. The amount of utilizable vitamin and the rate at which it was exuded depended on the algal species and conditions of culturing. Aaronson et al. [149] showed that when O. danicus (chrysophyceae) was grown on a defined medium the cells excreted a number of vitamins including riboflavin, vitamin E and nicotinic acid in addition to four amino acids. Swift [150] published an excellent review of phytoplankton production, excretion and utihzation of vitamins. 

B/r or B/2 witB a generation time of 3-4 h. To induce development to the aggregation-competent stage, the cells are harvested during exponential growth, washed, and starved in non-nutrient buffer see Note 8). Since the cells stimulate their own development by the periodic generation of cAMP pulses, the time they need for development will strongly depend on their density. 

Cells are cultivated in shaken suspension in nutrient medium and harvested during exponential growth (cell density not higher than 5 X 10 /mL). The cells are washed three times in PB, adjusted in the buffer to 1 x 10 /mL, and 30 mL of the suspension are shaken in 100-mL Erlenmeyer flasks. In strain AX3 the development needs to be stimulated by cAMP pulses, and in strain AX2 the development is enhanced by pulsatile stimulation. For this, cAMP is dropped into the cell suspension every 6 min to 200 nM final concentration at each pulse (for instance, 16 p,L droplets of 4 X 10 M cAMP) applied through a pump, e.g., the peristalsis-ftee pump listed up under Subheading 2.3, item 9 or a medical perfusor pump. 

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