Logarithmic phase

The death rate coefficient is usually relatively small unless inhibitoiy substances accumulate, so Eq. (24-10) shows an exponential rise until S becomes depleted to reduce [L. This explains the usual growth curve (Fig. 24-21) with its lag phase, logarithmic phase, resting phase, and declining phase as the effect of takes over. 

Batch fermentation is the most widely used method of amino add production. Here the fermentation is a dosed culture system which contains an initial, limited amount of nutrient. After the seed inoculum has been introduced the cells start to grow at the expense of the nutrients that are available. A short adaptation time is usually necessary (lag phase) before cells enter the logarithmic growth phase (exponential phase). Nutrients soon become limited and they enter the stationary phase in which growth has (almost) ceased. In amino add fermentations, production of the amino add normally starts in the early logarithmic phase and continues through the stationary phase. 

These results show that the 2,4-dichlorophenoxyacetic acid can remain stable, and exert its herbicidal effects, only during the initial lag phase before the rapid logarithmic phase of destruction takes place. This initial lag phase depends upon the previous treatment of the soil, particularly on whether it has already been exposed to 2,4-dichlorophenoxyacetic acid. Clearly, once a soil is enriched with 2,4-dichlorophenoxyacetic acid destroying organisms, the herbicide, if added to the soil, will have little or no value in the control of plants growing there. 

In addition to the differences in phospholipid content between microbial and host cell membranes, it has been demonstrated that disparity exists between the transmembrane potentials of both organisms. The transmembrane potential is defined by the proton flux between the inner and outer bilayers of the cytoplasmic membrane and ranges from —90 to —110 mV in normal mammalian cells in contrast to transmembrane potentials of —130 to —150mV for logarithmic phase microbes. The differences in these electrochemical gradients have been postulated to drive the influx of peptides into the cell and thus act as a crucial barrier for defining host defense peptide selectivity. ... 

Harvesting of cells or product occurs best during at the end of the logarithmic phase or during the stationary phase. 

Breines, D., Burnham, J. Modulation of Escherichia coli type 1 fimbrial expression and adherence to uroepithelial cells following exposure of logarithmic phase cells to quinolones at subinhibitory concentrations. J Antimicrob Chemother 1994 34 205-21. 

In another experiment, the growth temperature for E. coli logarithmic phase cells was shifted up from 30°C to 42°C and subsequently incubated for 40 min. The tolerance of the cells to freeze-drying increased significantly in the specimen... 

Population doubling time The interval calculated during the logarithmic phase of growth in which, for example, 1.0 x 10 cells increase to 2.0 x 10 cells. This term is not synonymous with the term cell generation time. 

Add 2 mL of the overnight culture to 200 mL of L-broth. Continue incubation at 37°C with vigorous shaking (300 cycles/min in a rotary shaker) until the culture has reached the logarithmic phase of growth. This normally takes 3 h. 

In pathogenic bacteria, SOD may be a virulence factor. Strains of Mycobacterium tuberculosis and Nocardia asteroides that secrete FeSOD during logarithmic phase growth are resistant to phagocytic attack, while non-secreting strains are less virulent. 

While the general DNA polymerase activity found in T. spiralis muscle larvae crude extract was 0.7 0% mnol/h/mg protein (N = 2), the corresponding activity assayed under conditions preferred by DNA polymerase a was 4.6 74% nmol/h/mg protein (N = 2). As a reference, the two sets of assay conditions were used with crude extracts from mouse leukemia L1210 cells (harvested in the logarithmic phase of growth) and the corresponding activities determined as 1.4 nmol/h/mg protein (N = 1) and 3.7 mnol/h/mg protein (N = 1), respectively. 

Ribonucleotide reductase activity, comparable to that (0.7 nmol/h/mg protein N = 1) determined in murine leukemia LI210 cells (harvested in the logarithmic phase of growth) was fund in extracts from T. spiralis muscle larvae (0.2 nmol/h/mg protein N = 1), as well as from all C. elegans developmental forms studied, including dauer larvae (0.47 0.07 nmol/h/mg protein N = 3), mixed population of developing larvae (0.64 6% mnol/h/mg protein N = 2) and adults (0.7 0.06 nmol/h/mg protein N = 3). 

First is the application of substances under study in fractionated lanolin as 5 microliter droplets to sear left after bract removal. A critical condition for sensitivity in the bioassay is the length of the stem which has to be approximately 5-10 mm long and must be at the early stage of the logarithmic phase of growth. Application in lanolin is important because it appears that BRst must be in continual contact with the plant. When BRst are removed, or applied in water, ethanol or another solution, the concentration of... 

Luminous cells were grown in a seawater complete (SWC) liquid medium at about 16 °C unless otherwise specified. A 250-mL of the glowing medium in the logarithmic phase was used to measure BL emissions under various conditions of O2 concentration, pH and cell population. 

During the middle of the logarithmic phase, the yellow BL band of the V. fischeri Y1 becomes markedly distinct. As the cell-growth comes closer to the stationary phase, the yellow BL band is sharply weakened, whereas the blue-green BL band does not develop a tendency to drop. Under such conditions where the yellow BL is no more a primary light component, it was found that a supply of O2 to the culture triggers the enhancement of the yellow BL band remarkably (Fig. 1). The yellow BL band enhancement is distinctly observed when the cell population was considerably high in the stationary phase. 

Microbial monitoring based on ATP must be used with caution because different microbes possess different amounts of ATP and also metabolically active cells might harbor more ATP. We noticed that highest ATP was synthesized in early logarithmic phase (2 to 6 h) and the ATP pool decreased during early stationary phase (10 to 16-h) for boto Gram-positive and Gram-... 

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