Continuous fermentation using

Many papers on continuous fermentation using electrodialysis have been reported.34 If ionic products produced in the fermentation broth amino acids, carboxylates, etc. are removed from the broth by electrodialysis, continuous fermentation becomes possible. The diffusion behavior of organic acids, such as, acetic, propionic, lactic, tartaric, oxalic, or citric acid through cation78 and anion79 exchange membranes has been studied in detail in connection with the removal of organic acids from the fermentation broth, and in applications in the food industry. 

Wee YJ, Ryu HW (2009) Lactic acid production by Lactobacillus sp. RKY2 in a cell-iccycle continuous fermentation using lignocellulosic hydrolyzatcs as inexpensive raw materials. Bioresour Technol 100 4262-4270. doi 10.1016/j.biot1ech.2009.03.074... 

Propanediol Carbon substrate Glycerol Continuous fermentation using Klebsiella pneumoniae 5.5-8.8g/L/h Polyesters and polyurethanes synthesis Shell Menzel et al. (1997), Papanikolaou et al. (2000)... 

Despite the advantages of continuous cultures, the technique has found little application in the fermentation industry. A multi-stage system is the most common continuous fermentation and has been used in the fermentation of glutamic add. The start-up of a multi-stage continuous system proceeds as follows. Initially, batch fermentation is commenced in each vessel. Fresh medium is introduced in the first vessel, and the outflow from this proceeds into the next vessel. The overall flow rate is then adjusted so that the substrate is completely consumed in the last vessel, and the intended product accumulated. The concentration of cells, products and substrate will then reach a steady state. The optimum number of vessels and rate of medium input can be calculated from simple batch experiments. 

Najfpour, G.D., Propionic and Acetic Acid Fermentation using Propionibacterium acidipropionici in Batch and Continuous Culture , Ph.D. thesis, University of Arkansas, Fayetteville, AR, 1983. 

A high glucose concentration of 150 g l 1 was used in continuous fermentation with immobilised S. cerevisiae the obtained data for sugar consumption and ethanol production with retention time are shown in Figure 8.13. As the retention time gradually increased the glucose concentration chopped, while the ethanol concentration profile showed an increase. The maximum ethanol concentration of 47 g l 1 was obtained with a retention time of 7 hours. The yield of ethanol production was approximately 38% compared with batch data, where only an 8% improvement was achieved. 

In fermentation for the production of acetic acid, ethyl alcohol is used in an aerobic process. In an ethanol oxidation process, the biocatalyst Acetobacter aceti was used to convert ethanol to acetic acid under aerobic conditions. A continuous fermentation for vinegar production was proposed for utilisation of non-viable A. aceti immobilised on the surface of alginate beads. 

The experiment is accomplished with a 2 litre B. Braun fermenter biostat (Germany) equipped with DO and pH meters. Temperature and level controllers are very sensitive, with highly accurate response from the sensors installed in the vessel. Figure 10.7 shows a perfect continuous fermentation set up used in photosynthetic production. A small modification of... 

One reactant is sparingly soluble in the reaction phase and would be depleted were it not added continuously. Oxygen used in an aerobic fermentation is a typical example. 

In spite of several drawbacks (i.e. expensive and laborious handling procedures, low space-time yields (Table 2.1), high demand on biosafety, potential contaminations, limited applicability for continuous fermentations [129], and problems obtaining the same glycosyla-tion profile from batch to batch [130]), mammalian cell cultures are widely used for small-scale expression and more recently even on a multi-cubic-meter scale. The system works like insect... 

Nguyen, V. T., and Shieh, W. K., Continuous Ethanol Fermentation Using Immobilized Yeast in a Fluidized Bed Reactor, J. Chem. Tech. Biotechnol., 55 339 (1992)... 

A continuous fermenter is operated at a series of dilution rates though at constant, sterile, feed concentration, pH, aeration rate and temperature. The following data were obtained when the limiting substrate concentration was 1200 mg/1 and the working volume of the fermenter was 9.8 1. Estimate the kinetic constants Km, //, and kd as used in the modified Monod equation ... 

Table 1. Data of parameters used for simulation of fermentation in bacth and continuous fermenters shown in Fig. 9-12...

Stirred-tank reactors can be used for continuous fermentation, because cells can grow in this type of fermentors without their being added to the feed medium. In contrast, if a plug flow reactor is used for continuous fermentation, then it is necessary to add the cells continuously in the feed medium, but this makes the operation more difficult. 

Ariff and Webb studied production of glucoamylase using freely suspended cells of Aspergillus awamori in batch and continuous fermentations. Glucoamylase yields based on glucose consumed were 900 and 1080 U/g for batch and continuous fermentations, respectively. The immobilization of viable cells was achieved by adsorption to cubes of reticulated polyurethane foam. In comp uison with freely suspended cell fermentations, neither batch nor continuous fermentations of immobilized cells improved glucoamylase production significantly in tenns of yield or productivity. 

It is frequently desirable, particularly in the field of waste-water treatment, to operate a continuous fermenter at high dilution rates. With a simple stirred-tank this has two effects—one is that the substrate concentration in the effluent will rise, and the other is that such a system in practice tends to be unstable. One solution to this problem is to use a fermenter with a larger working volume, but an alternative strategy is to devise a method to retain the biomass in the fermenter whilst allowing the spent feed to pass out. There are several methods by which this may be achieved (see Fig. 5.60), and the net effect is the same in each case, but the analysis might... 

In contrast to the batch fermentation based methods of determining kinetic constants, the use of a continuous fermenter (Fig. 3.71) requires more experiments to be performed, but the analysis tends to be more straightforward. In essence, the experimental method involves setting up a continuous stirred-tank fermenter to grow the micro-organisms on a sterile feed of the required substrate. The feed flowrate is adjusted to the desired value which, of course, must produce a dilution rate below the critical value for washout, and the system is allowed to reach steady state. Careful measurements of the microbial density X, the substrate concentration S, and the flowrate F are made when a steady state has been achieved, and the operation is then repeated at a series of suitable dilution rates. 

Kaufman, E.N., Cooper, S.P., and Davison, B.H. 1994. Screening of resins for use in a biparticle fluidized-bed bioreactor for the continuous fermentation and separation of lactic acid. Appl. Biochem. Biotech. 45-46, 545-554. 

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