Growth decline 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. 

The growth of microbial populations is normally limited either by the exhaustion of available nutrients or by the accumulation of toxic products of metabolism. As a consequence, the rate of growth declines and growth eventually stops. At this point a culture is said to be in the stationary phase. The transition between the exponential phase and the stationary phase involves a period of unbalanced growth during which the various cellular components are synthesized at unequal rates. Consequently, cells in the stationary phase have a chemical composition different from that of cells in the exponential phase. 

The rate of change of px at the decline phase can also help in phenomena identification. For example, an abrupt fall in the px value is an indication of nutrient limitation. Once the limiting nutrient has reached a critical concentration, complete depletion and a decrease in growth will occur quickly. On the other hand, when a reduction of px occurs slowly, the phenomenon responsible is usually the formation of an inhibiting metabolite, which has gradually accumulated in the system. 

The same effect of bacterial contaminations was observed with an electronic nose equipped with CP sensors in an antibiotic fermentation with Micro-monospora carbonacea [34]. Infections of E. coli and Gram-positive bacteria can be discriminated in the plot. The same culture also exhibited characteristic response patterns at the different fermentation stages over a nine-day period. The character of the trajectory in the PCA mirrored the growth phase, the antibiotic synthesis phase as well as the declination phase. The starting point of the trajectory almost coincided with the end point. 

Fig. 3.8 Typical bacterial growth curve in closed batch liquid culture. (A) Lag or adaptive phase (B) logarithmic or exponential phase (C) stationary phase (D) decline phase.

At the end of the lag phase, growth begins and cell concentration increases exponentially. As the available nutrients are exhausted in the medium, the rate of growth declines and growth eventually stops. The stationary phase is usually followed by a death phase, in which the organisms in the population die due to the depletion of the cellular reserves of energy or due to the accumulation of toxic products. 

The time course curve, or growth curve, for a batch culture usually consists of six phases, namely the lag, accelerating, exponential growth, decelerating, stationary, and declining phases. 

Finally, growth stops in the stationary phase. In some cases the rate of cell growth is limited by the supply of oxygen to the medium. When the stationary phase cells begin to die and destroy themselves (by lysis) in the declining phase, the result is a decrease in the cell concentration. 

Figure 5.19. Representation of the numerical Kono approach in a. c/t diagram of growth (a) and a kinetic plot versus x (b). In agreement with different well-known growth phases I-IV, (cf. Fig. 5.23, lag phase, I transition, II exponential. III and S-limitation decline phase, IV), and incorporating a linear growth phase in case of transport limitations (V in case B instead of exponential case A), numerical values can be taken from the plots to quantify the growth behavior with concentrations at certain times Xq — inoculum at Iq, — lag-time, = critical concentration at critical time...

Decline phase (1) The fourth of four major phases of the bacterial growth curve in which cells lose their abihty to divide (due to less supportive conditions in the medium) and thus die. (2) In the stages of a disease, the period during which the host defense finally overcome the pathogen and symptoms begin to subside. 

Products have a life cycle which includes different phases the introduction, growth, maturity and decline phase (Fig. 2.2). 

The cycle starts with the product idea, the product test and finally the introduction into the market. In the beginning major costs accumulate due to the development of the product. When customers see the benefits of the product, the purchasing begins and the growth phase starts. Revenne starts to increase and profit increases to a positive level. The market reaches satnration in the maturity phase, which leads in the following to an intensified competition between prod-nets. The curve reaches the point of inflection and an overall decrease in profit and revenue starts to set in. In the decline phase profit decreases further and loss sets in here it becomes necessary to either take the product from the market or start relaunching the product through different performance features. Another possibility is the introduction of a new product onto the market. 

Estimating microbiological population density and diversity plays important and often pivotal roles at several junctures in the winemaking process. For instance, it is frequently necessary to determine changes in microbial populations during the preparation of starter cultures, growth and decline phases of malolactic fermentation, or monitoring potential Brettanomyces infections. 

A well-known marketing concept that holds that products pass through phases in their market lives. These are generally the inception, growth, maturity, and decline phases. The presence of the product life cycle has implications for supply chain design. Chapter 5... 

The growth phase lasts for several days and raises the population to around 10 UFC/ml or more. Evidently, its duration also depends on the composition of the medium. The subsequent stationary phase also varies. The bacteria then begin the decline phase. As soon as the mahc acid is completely transformed, sulfiting is used to eliminate the bacteria as quickly as possible. 

Both methods give the same results for bacterial suspensions in the growth phase. When they move into the stationary, and then the decline phase, the difference between the results increases. While counting by epifluorescence shows a slight decrease in the number of cells, there is a sharp drop in the number of colonies visible. This difference may be explained by the fact that part of the population of fluorescent cells is still biologically active but is incapable of the metabolic and physiological functions necessary for multiplication. They are described as viable, non-cultivable (VNC) cells. Table 6.3 shows the lactic bacteria count after sulfiting a wine. 

Declining growth A growth phase in which the availability of food begins to limit cell growth. 

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