Bacterial growth, steady state

Note that this result is independent of the concentration of glycerol in the input stream as long as the other necessary nutrients for growth are sufficient. This result is also independent of the original size of the inoculum. The bacteria simply increase in number until their use of glycerol in the tank (100 /iM - 26 /iM = 74 /iM) corresponds to the bacterial biomass they form during a tank detention time. To obtain an estimate of this steady-state bacterial biomass, we use the glycerol mass balance equation ... 

Several studies have measured DFAA concentrations and turnover (see Chapter 4 and Munster, 1993), but here we concentrate on those that compare DFAA uptake with bacterial production. The fraction of bacterial production supported by DFAA is one index for the relative importance of amino acids, not only in supporting bacterial growth but also in the overall flux of DOM. ( Flux is used here to indicate both production and uptake in a quasi-steady state.) If DOM concentrations are constant, DOM production will equal total uptake rates by microbes there is no evidence of photo-oxidation of amino acids and of the other compounds discussed here (see Chapter 10). Total uptake includes respiration and assimilation into biomass. Here assimilation is defined as the appearance of a radioactive compound in cells (both cellular LMW and HMW pools) respiration is excluded. 

Values of q >1 thus correspond to steady states with carbon-limited bacterial growth rate, whereas values of q <1 correspond to mineral nutrient limitation. Equation (3) illustrates how everything depends on everything in a steady-state situation. The value of q is a function not only of the ratio between production rate of organic bacterial substrates and the product of loss rates of the bacterial predators and competitors to higher predators, but also of all the parameters representing physiological properties of bacteria, bacterial competitors, and bacterial predators. 

There is much discrepancy in literature concerning the extent of bacterial productivity in the sea. Whittaker and Likens (1973) demonstrated a theoretical approach in treating the biosphere as a system in steady state in which total respiration of all heterotrophic organisms essentially equals total net primary productivity. Given this equality, total reducer (bacterial and fungal) assimilation should approximately equal net primary production minus animal assimilation. With an assumed growth efficiency of 5—10% for marine reducers, then marine reducer production would be 0.7 to 1.4 X 10 t C yr , or about half to about the same as the authors estimated marine animal production (= 1.376 X 10 t C yr ). 

Our second experimental system consisted of two chemostats linked in series. In the first vessel the bacterial prey was allowed to come to steady state and then fed into the second stage vessel which contained the amoebae. As the limiting nutrient source for the bacteria is virtually exhausted under steady state conditions, it was assumed that no further growth of prey occurred in the second vessel. In the second vessel the equation of balance for the predator is ... 

Figure 7. Typical steady state profiles of dimensionless bacterial density, v, and dimensionless substrate concentration, u. In the growth zone, w < < 7, u > Uc, and bacterial growth can be supported. In the depleted zone, 0 < < w, u = Ue, and bacterial growth cannot be supported.

Bronk BV, Reinisch L (1993) Variability of steady state bacterial fluorescence with respect to growth conditions. Appl Spectrosc 47 436... 

For many practical purposes large scale bacterial production is carried out in a chemostat. This device, a further development of the method used by Novick Szilard (1950) and Monod (1950), allows continuous growth by constant removal of organisms and addition of nutrients, as well as the neutralization of inhibitory products, for instance by keeping pH constant. The design of the process is described by Herbert, Elsworth TeUing (1956) and a brief summary of the theory will be discussed as an example of steady state behaviour. 

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