Biomass concentration

Intracellular reduced pyridine nucleotides NAD(P)H are the primary suppliers of reducing power to anabolic and catabolic pathways. They can be measured because of their fluorescent properties. 16) The fluorescence is caused by the presence of the reduced forms of the pyridine nucleotides NADH and NADPH (jointly referred to as NAD(P)H). These fluorophores absorb light in a wide band around 340 nm, and reemit, or fluoresce, light in a wide band around 460 nm. The phosphorylated and nonphos-phorylated nucleotides have essentially equivalent fluorescence properties while the oxidized forms of these nucleotides are nonfluorescent. 

It was known that the intracellular concentrations of the reduced and oxidized forms of the pyridine nucleotides vary in different cell types and under different cell culture conditions.(17) Harrison and Chance applied the NAD(P)H fluorescence technique and found that culture fluorescence can be related to the metabolic state of the cells. 18,19) Since then, more than a hundred papers on NAD(P)H fluorometry have been published. However, they are primarily divided into three major categories  

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Other appHcations of firefly hioluminescence include measurement of the activity of bacteria in secondary sewage treatment activated sludge (296,297), detection of bacteria in clean rooms and operating rooms, measurement of bacteria in bottled foods, beverages (298), and pharmaceuticals (299), determination of the antimicrobial activity of potential dmgs (300), determination of the viabiHty of seeds (301), and measuring marine biomass concentrations as a function of ocean depth or geographical location (302). 

For a soluble wastewater, the VSS is proportional to the biomass concentration. Process performance may also be related to the sludge age, which is the average length of time the organisms are in the process. 

Fig. 11. Aerobic biological treatment, where Sq = initial organic concentration and Xq = initial biomass concentration (—...

In these equations, [L = specific growth rate coefficient, v = specific rate of substrate uptake, t = time, x = biomass concentration, Sj = intracellular substrate, and Cj = concentration of intracellular substrate. Several examples where these equations can be applied include nitrogen hmitations in M. citrifolia cultures and phosphate hmited growth in C. roseus, N. tahacum, a.nd Papaver. somniferum. 

A steady state is when the conditions in the bioreactor (biomass concentration, residual substrate concentration etc) remain constant over time. 

Aim3 aerobic bioprocess was operated in a continuous mode with nitrogen as the growth limiting nutrient. The steady state biomass concentration (x), the biomass yield coefficient (Yx/S) and the product yield coefficient (Yp/t) were determined at a low and at a high dilution rate (D). 

Productivity. The continuous system operates such that the biomass concentration remains constant (specific growth rate = dilution rate). Productivity is therefore given by the biomass concentration x the dilution rate. 

Compare a) the minimum OTR and b) heat evolution rate of a continuous fermentation system based on n-alkanes operating at a dilution rate of 0.2 h 1 and a biomass concentration of 13.5 kg m 3, to a similar system based on carbohydrate. You may need to look back a few pages to get the relevant information concerning carbohydrate utilisation (Section 4.7). 

Biomass formation and transamination activity within the cells develop in a similar manner. Growth usually continues until limited by the availability of dissolved oxygen tension (DOT). After 10-15 hours a dry weight biomass concentration of 10 g V is normally reached. 

Dilution rate 0.4 h"1 gives highest productivity, but 25% of the substrate remains unused. Dilution rate 0.3 h"Y gives better substrate utilisation but with reduced productivity. Both these dilution rates require minimum OTRs greater than the bioreactor can supply. This means that such biomass concentrations could not be produced in practice. 

Reactor weight Foam level Off gas composition Biomass concentration... 

At steady-state condition, the biomass concentration remains constant, that is, dX/dt = 0, and (5.6.1.3) concludes to /x = /) therefore the specific growth rate is equal to the dilution rate. 

The average biomass concentration is defined as the product of yield of biomass and change of substrate concentrations in inlet and outlet streams. The biomass balance is ... 

Biomass concentration is obtained from definition as substrate is utilised it is converted to cells or biomass ... 

Biomass concentration must remain high enough to show high yield. 

A Monod rate model is used to demonstrate the rate of biomass generation. We neglect the cell death rate. Let us denote the ratio of biomass rate of generation to biomass concentration, rJX, that is the specific growth rate /a also denotes the dilution rate D is defined as number of tank volumes passed through per unit time, FIV. After substitution of D and /a into (6.8.1), the following equation is obtained ... 

For each run, calculate and plot the cell biomass concentration, glucose concentration, ethanol concentration, and pH as a function of time. Identify the major phases in batch fermentation lag, exponential, stationary and death. 

Table E.1.1. Substrate concentration versus inverse biomass concentration...

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