Fermentation operation

Oxygen, when introduced into fish-farming ponds and pools, particularly trout pools, enables these fish to increase their food intake and hence grow more rapidly (see Aquaculture chemicals). Fermentation operations are accelerated by sparging with oxygen (see Aeration,biotechnology Ferl ntation). 

Fungi are microscopic nonphotosynthetic plants which include in their classification yeast and molds. Yeasts have a commercial value as they are used for fermentation operations in distilling and brewing. When anaerobic conditions exist, yeasts metabolize sugar, manufacturing alcohol from the synthesis of new cells. Alcohol... 

Studies show that the production of 1kg dry biomass requires 2.0 kg sugar, 0.7 kg oxygen, 0.1 kg ammonia, with the liberation of 12,300 k Joules heat. A typical continuous fermentation operates at a dilution rate (D) = 0.2 h 1, with sugar concentration of 3% (w/v) in the incoming medium. With a fermentor of 50 m3 capacity and 90% utilisation of carbohydrate [ie 0.3% (w/v) sugar in the outgoing medium] what would be ... 

This bioreactor mode refers to a tank fermenter operated semi-continuously. The rate of the feed flow, F0, may be variable, and there is no outlet flow rate from the fermentor. As a consequence of feeding the reactor volume will change with respect to time. 

The steady-stale substrate and biomass concentrations for a continuous stirred-tank fermenter operated at various dilution rates are given below. Given that the fresh feed concentration is 700 mg/l, calculate the values of the Monod constants and Ks the yield coefficient, Y and the endogenous respiration coefficient kd. 

As in the case of enzymes, whole cells can be immobilized for several advantages over traditional cultivation techniques. By immobilizing the cells, process design can be simplified since cells attached to large particles or on surfaces are easily separated from product stream. This ensures continuous fermenter operation without the danger of cell washout. Immobilization can also provide conditions conducive to cell differentiation and cell-to-cell communication, thereby encouraging production of high yields of secondary metabolites. Immobilization can protect cells and thereby decrease problems related to shear forces. 

Many applications exist for nltra.filtTa.tion in the biotechnology industry. A typical application is the concentration and removal of products from fermentation operations used in enzyme production, cell harvesting, or virus production. Most of the systems are small the volume processed is often only 100 to 1000 gal/day, but the value of products is often very high. Batch systems are commonly used. 

If, however, B-C, the interval for maximum production rate, is short relative to the total fermenter operating time, then continuous operation is generally favored (Eq. 16.2). 

One of the drawbacks in the current commercial fermentation process is that the predominant form of the product is the deprotonated lactate rather than lactic acid, requiring more expensive and wasteful product purification steps. This is because the Lactobacillus fermentation operates at a minimum pH of 5.0-5.5 which is above the pA a of lactic acid (3.87). To overcome this limitation, a powerful strain improvement method, genome shuffling, was used to improve the acid tolerance of a poorly characterized industrial strain of LactobacillusA population of strains with subtle improvement in pH tolerance was isolated using classical strain improvement methods such as chemostats, and were then shuffled by recursive pool-wise protoplast fusion to create mutant strains that grow at substantially lower pH than does the wild-type strain. 

When pure cultures are used, fermentations must be carried out aseptically. Thus, the media must be sterilized and the fermenter operated under aseptic conditions. If foreign organisms contaminate the culture, they can over-run the desired culture or destroy the product. 

Keywords. Cellulase production. Solid-state fermentation. Operating conditions, Bioreactor, Mathematical model... 

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