Fermentation aerobic

A commercial technology (69), the SABRE process, treats contaminated water and soil ia a two-stage process by adding a readily degradable carbon and an inoculum of anaerobic bacteria able to degrade the contaminant. An initial aerobic fermentation removes oxygen so that the subsequent reduction of the contaminant is not accompanied by oxidative polymerization. 

Welan Gum. This gum is produced by a carefiiUy controUed aerobic fermentation using 2nc. ydlcaligenes strain (ATCC 31555) (88). The backbone... 

Welan is produced by 2is Pilcaligenes species (ATCC-31555) by aerobic fermentation, and marketed under the trade name BIOZAN (Merck and Co., Inc.) early reports also referred to it as S-130 (229). The polymer is stmcturaUy similar to geUan, sharing the same backbone sequence. It has an additional side group of an a-L-rhamnopyranosyl or an a-L-maimopyranosyl (Man ) unit linked (1— 3) to a P-D-glucopyranosyl unit in the backbone of the polymer ... 

MacroHdes are obtained by controUed submerged aerobic fermentations of soil microorganisms. Although species of Streptomjces have dominated, species of Saccharopoljspora Micromonospora and Streptoverticillium are also weU represented. New techniques such as enzyme-linked immunosorbent assay (ELISA) based assays may prove beneficial for discovering new stmctures (464). 

A commercial bacterial cellulose product (CeUulon) was recently introduced by Weyerhaeuser (12). The fiber is produced by an aerobic fermentation of glucose from com symp in an agitated fermentor (13,14). Because of a small particle diameter (10 P-m), it has a surface area 300 times greater than normal wood cellulose, and gives a smooth mouthfeel to formulations in which it is included. CeUulon has an unusual level of water binding and works with other viscosity builders to improve their effectiveness. It is anticipated that it wiU achieve GRAS status, and is neutral in sensory quaUty microcrystaUine ceUulose has similar attributes. 

Aerobic Fermentation The classic example of large-scale aerobic fermentation is the production of penicillin by the growth of a specific mold. Commercial vessel sizes are 40,000 to 200,000 L (1,400 to 7,000 ft ). The operation is semibatch in that the lactose or glucose nutrient and air are charged at controlled rates to a precharged batch of liquid nutrients and cell mass. Reaction time is 5 to 6 days. 

The magnitude of the air sterilization problem is seen from the usual needs of a highly aerobic fermentation where roughly 1 volume of air per volume of medium per minute may be used. For a factoiy with 20 fermenters of 100,000 1 (3500 fH) each, 2 million Em (70,000 ftVm) of air is handled. Very large compressors are used, and at least two are required so that one can be down for maintenance. 

Fig ure 11-23. Piping and instrumentation diagram of a fermenter. (Source Bartow [13], Supersizing the aerobic fermenter," Chem ca Engineering, pp. 70-75, July 1999. Courtesy of Chemical Engineering.)... 

The pH is adjusted to 6.9 to 7.0 before sterilization and aerobic fermentation is effected for 24 hours (until the packed cell volume is about 10 to 15%) under the following conditions temperature, 37°C sterile air input, 54 ftVmin pressure, 7 psi and agitation,... 

The Fermentation Process The process by which this antifungal substance is produced is an aerobic fermentation of an aquaous nutrient medium inoculated with a pimaricin-producing strain of Streptomycesgihrosporeus. The nutrient medium contains an assimilable source of carbon such as starch, molasses, or glycerol, an assimilable source of nitrogen such as corn steep liquor and Inorganic cations such as potassium, sodium or calcium, and anions such as sulfate, phosphate or chloride. Trace elements such as boron, molybdenum or copper are supplied as needed in the form of impurities by the other constituents of the medium. 

Prior to sterilizing the abovedescribed medium, adjust the pH to 8. Aerobically ferment for 66 to 90 hours while stirring at 250 rpm with air input at 4.5 C/)2/min and 25 psi. The potency of the antibiotic produced at the end of this period reaches a peak of 150 to 225 jug/ml and remains relatively constant. The pH of the fermentation medium changes slightly during the antibiotic production, varying in the range of 6.8 to 7.3. 

The process for producing spiramycin comprises inoculating an aqueous nutrient medium with a culture of the NRR L No. 2420, allowing aerobic fermentation to take place and separating from the culture medium the spiramycin thus formed. The culture medium also contains the antibiotic substance known as Congocidin which, however, does not possess the same useful properties as spiramycin and which can be isolated in crystalline form. The separation of the two antibiotic substances is readily achieved. 

The empirical formula for glucose is C6H12O6 and for itaconic add it is C5H6O4, so itaconic add production is another aerobic fermentation and requires aeration. 

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. 

Many semibatch reactions involve more than one phase and are thus classified as heterogeneous. Examples are aerobic fermentations, where oxygen is supplied continuously to a liquid substrate, and chemical vapor deposition reactors, where gaseous reactants are supplied continuously to a solid substrate. Typically, the overall reaction rate wiU be limited by the rate of interphase mass transfer. Such systems are treated using the methods of Chapters 10 and 11. Occasionally, the reaction will be kinetically limited so that the transferred component saturates the reaction phase. The system can then be treated as a batch reaction, with the concentration of the transferred component being dictated by its solubility. The early stages of a batch fermentation will behave in this fashion, but will shift to a mass transfer limitation as the cell mass and thus the oxygen demand increase. 

Aerobic fermentation Water-l-organic carbon source Air Bacteria... 

Example 11.1 Suppose an aerobic fermentation is being conducted in an agitated vessel at 38°C and that k , = 0.1s and kgT, = 20s have been measured for the mass transfer of oxygen from air at atmospheric pressure. Determine A/H, and KgAi. 

An aerobic fermentation where by-product CO2 is allowed to escape... 

Groen, D.J., Noorman, H.J., and Stankiewicz, A. (2005) Improved method for aerobic fermentation intensification, in Proceedings of the International Conference Sustainable (Bio)Chemical Process Technology,... 

Scleroglucan is a polysaccharide secreted by the mycelia of certain microorganisms. It is produced by aerobic fermentation of D-glucose by such microorganisms. Scleroglucan has been proposed as a better alternative to xanthan gum for drilling fluid compositions [666]. 

Wellan gum is produced by aerobic fermentation. The backbone of wellan gum is identical to gellan gum, but it has a side chain consisting of L-mannose or L-rhamnose. It is used in fluid loss additives and is extremely compatible with calcium ions in alkaline solutions. 

Acetobacter bacteria oxidatively convert wine to vinegar through an aerobic fermentation of ethanol (a primary alcohol) into acetic acid (a carboxylic acid) ... 

This gum was the first microbial gum to be used in the food industry. It is produced by the aerobic fermentation of Xanthomonas campestris. A specially selected culture is grown on a carbohydrate-containing nutrient medium with a nitrogen source and other essential elements. The pH, temperature and aeration are controlled carefully. The product is then sterilised and the gum is precipitated with propan-2-ol. Next, the precipitate is washed, then pressed to remove residual alcohol, followed by drying and grinding to the required size. 

BIOKOP A process for treating liquid effluents containing wastes from organic chemical manufacture. It combines aerobic fermentation, in special reactors known as BIOHOCH reactors, with treatment by powdered activated carbon. Developed originally for treating the effluent from the Griesheim works of Hoechst, it was engineered by Uhde and is now offered by that company. See also PACT. 

Ensio-Fenox A process for removing chlorinated phenols from pulp-bleaching effluents. It combines anaerobic and aerobic fermentation processes. 

Figure 12.4 illustrates some modes of operation of semicontinuous reactors. In Figure 12.4(a), depicting a gas-liquid reaction of the type A(g) + B(f) - products, reactant A is dispersed (bubbled) continuously through a batch of reactant B an important example is an aerobic fermentation in which air (or 02) is supplied continuously to a liquid substrate (e.g., a batch of culture, as in penicillin production). In Figure 12.4(b),... 

---