Exponential phase of growth

Sub-cellular fractionation of five strains reveal the same numbers of bands. The distribution of PG activity in sub-cellular organelles was broadly similar in these five strains. PG activity was detected in low-density vesicles, vacuoles and ER fractions in samples harvested during the early exponential phase of growth. However, PG levels were always lower (at least 1.5 fold) than those found in wild type. Cells of the mutants harvested during stationary phase of growth showed that 84% of total intracellular PG activity was located in the vesicle fraction. No intracellular PG activity was found in stationary phase wild type cells. 

HCT-116 human colon carcinoma (ATCC, Bethesda MD) cells were grown in McCoy s 5A) and were routinely subcultured twice weekly. Antiproliferative assay was performed by chemoluminescence assay based on quantification of ATP. Cells in their exponential phase of growth were treated at different times (lh or 24h) with different concentrations of edotecarin or SN-38. For post-treatment recovery studies, cells were washed with PBS and left in drug-free culture medium. Then, cell medium was collected to avoid any cell loss. Cells in monolayer were washed, detached with trypsin, and collected in the medium. Cells were counted in a Multisizer 3 Coulter Counter to measure the drug s effects on growth inhibition. Samples were fixed either... 

Five different concentrations (0, 25, 50, 75, 100 mg/1) of explosives were added to the cultivation medium from stock solution of TNT (100 mg/ml, DMSO). The experiment were done in triplicates for particular concentration and harvest-day. The concentration which inhibits growth of suspension culture by 50% (IC50), was calculated from GVs, which corresponded to the end of exponential phase of growth and which differed for particular species. The GVs for different concentration of explosives were plotted and IC50 calculated. 

In another set of experiments, Schlesinger and Anderson (44) showed that the isozymes are formed in vivo by alteration of the dimer. Using an E. coli mutant that makes an altered subunit, which will only dimerize (in vitro or in vivo) in the presence of phosphate or zinc, they found that the monomers produced by the cell growing in the absence of phosphate and zinc produced only one electrophoretic form when the monomer was converted to the dimer in vitro. However, if the medium is made 2 vaM in phosphate and 10 /iM in zinc, in the exponential phase of growth, three isozymes are formed. Additional support for the conclusion that isozymes are made by alteration of the dimer comes from the fact that independent of when 14C-labeled amino acids are added to the growing culture, label appears first in isozyme I. It thus appears that a mechanism is available in the periplasmic space for the conversion of isozyme I to the other isozymes. 

The inoculum was prepared from the stock culture in 500-mL Erlen-meyer flasks containing 100 mL of the corresponding medium. Incubation was performed in a rotary shaker at 200 rpm and 30 1°C for 48 h with the cells in the exponential phase of growth. 

In the present work, the addition of microsalts and EDTA in the medium retarded biosurfactant synthesis, which was initiated only at the exponential phase of growth. The critical micelle concentration (CMC1) was reached at the onset of the stationary phase (after 50 h), although it is unknown whether surfactant production continued stationary phase. 

Scherl,A., Francois, P., Bento, M., Deshusses, J.M., Charbonnier, I., Converset, V., Huyghe, A., Walter,N., Hoogland, C., Appel, R.D., Sanchez, J.C., Zimmermann-Ivol, C.G., Corthals, G.L., Hochstrasser, D.F. and Schrenzel, J. (2005) Correlation of pro teomic and transcriptomic profiles of Staphylococcus aureus during the post-exponential phase of growth. J. Microbiol. Methods 60, 247-257. 

Cells can be inoculated at a normal inoculum level, e.g. 1-2 x 10 cells mL, and grown as a batch culture until the mid-exponential phase of growth. The supply of medium from the feed reservoir can then be started at a flow rate that gives the required dilution rate. In order that the cells are not washed out of the fermenter, the initial dilution rate should be below the maximum specific growth rate of the cells, although too low a dilution rate may result in low cell viability... 

Cells in exponential phase of growth are exposed to a cytotoxic drug. The duration of exposure is usually determined as the time required for maximal... 

Production of peptide antibiotics usually begins at the late-exponential phase of growth and continues during the early stages of the sporulation process in bacilli. 

Extracellular release is now well established as a part of the primary production. Rapidly growing phytoplankton releases 2-10% (PER) in most cases, increasing to 10-60% in the stationary phase of growth mainly because of a lower photosynthetic rate. There is increasing evidence that the absolute rate of release is highest in the exponential phase of growth. Nutrient limitation has been shown to increase the relative rate of release and nntrient ratios, i. e. N/P, also seems to be of importance. Extracellular release is relatively imaffected by irra-diance but PER is correlated to the relative inhibition of photosynthesis at high irradiances. 

The level of release according to Table 2 is from 2-10% and approaching 30% in one case in the exponential phase of growth, and from about 10-60% in the stationary phase. The reason for this large difference in percentage re-... 

PER (Taraldsvik and Myklestad, to be published). Thus monosaccharides constitute 36% of the total in this case where measurements were made in the exponential phase of growth. 

The maximum production of the D-fructan, levan, has been shown to occur during the mid-exponential to the late exponential phase of growth of Actinomyces viscosus and is followed by a rapid decline as a result of the production of levan hydrolase activity.The levan produced by Streptococcus mutans OMZ 176 appears to have a structure similar to other known D-fructans and inulin. On the basis of chemical shift displacements of the n.m.r. spectra, resulting from 0-substitution at specific carbon atoms, resonances have been assigned to the carbon atoms of the j3-D-fructofuranosyl residues in levans. A variety of different levans show almost identical n.m.r. spectra in contrast to a wide divergence in the corresponding spectra of dextrans. ... 

The ability of Monod s empirical relation to fit kinetic data for biochemical reactions has its foundations in generalizations of two phenomena frequently observed for fermentation processes (1) nature places a cap on the quantity of microorganism that can be achieved during the exponential phase of growth in a bioreactor operating in a batch mode and (2) as the concentration of the limiting substrate approaches zero, the rate laws for biochemical reactions approach pseudo-first-order behavior with respect to that substrate. The cap indicated on the cell growth rate has been associated with the natural limit on the maximum rate at which replication of DNA can be achieved. 

B. subtilis produces at least eight Eprs at the end of the exponential phase of growth in liquid culture [80]. These have been identified as the alkaline serine protease subtilisin (AprE) [81,82], the neutral protease (NprE) [83], the minor Epr [84,85], the bacillopeptidase F (Bpr) [86], the Vpr protease [87], the metalloprotease (Mpr) [86], the NprB [83], and the cell wall-associated extracellular protease WprA [88] (Figure 7.2). Proteomics and transcriptomics studies have shown the involvement of the DegS-DegU two-component regulatory system in the expression of several of these exoproteases [89,90]. 

Develop bacterial biofdms on the cut, sterile catheters by placing individual segments into Eppendorf tubes containing 1.0 mL of bacterial cell suspension in TSBG with 10 CFUs/mL in the exponential phase of growth. 

Incubate cultures statically at 37 °C with 5% CO2 to the mid-exponential phase of growth as previously determined by optical density at 600 nm (ODgoo) measurement. 

During the exponential phase of growth the population increases at a constant rate (Fig. 18.1). Thus, one expects the rate of increase of biomass (djc/d/) to be proportional to the amount of biomass (x) present ... 

Photoautotrophic air-grown cell suspension cultures of carnation (Dianthus caryophlllus L.) were routinely subcultured every four weeks using the Murashige and Skoog medium, as previousely described (6). Cells were harvested in the mid-log exponential phase of growth for the experiments. 

An unusual pattern of sulfate utilization was observed in growing cultures of P. shermanii. Uptake of S04 " by the cells had an oscillatory pattern, alternating between the periods of sulfate utilization and release (Fig. 4.1). The accumulation of S04 in the medium was maximal in the exponential phase of growth (24-28 h). 

The beneficial effect of mycobacterial culture liquid was due to its content of amino acids, vitamins, peptides, and possibly of specific stimulators of vitamin synthesis, since the vitamin content of the cells was increased to a greater extent than their biomass. Although amino acids exert a significant effect on the synthesis of vitamin Bn, the complete culture liquid of mycobacteria was more effective, which can be explained by the complex influence of many metabolites released by mycobacteria in the exponential phase of growth. Of special interest are polypeptides secreted by mycobacteria into the medium, which may have a specific stimulatory effect on vitamin Bn biosynthesis. Chromatographic separation of mycobacterial polypeptides is shown in Fig. 4.23B. Specific stimulatory effects were displayed by fractions 10, 11 and 12. 

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