Culture, fermentation

At the end of the incubation period the fermentation culture mixture is adjusted to pH 2 with concentrated hydrochloric acid, the solid material present is removed by filtration, and the filter cake is washed with water. The washings are combined with the main filtrate, adjusted to pH 7.0, and 15.5 liters of the filtered culture liquid is introduced into a columnar exchanger d /a" i.d.) packed with 380 ml of carboxylic acid resin which has been preliminarily washed in succession with two liters of an aqueous solution of 37.5 grams of sodium hydroxide and with two liters of water. The column containing paromomycin is washed with two hold-up volumes of water and is eluted with 0.5 N hydrochloric acid. 

Batch reactors are often used for liquid phase reactions, particularly when the required production is small. They are seldom employed on a commercial scale for gas-phase reactions because the quantity of product that can be produced in reasonably sized reactors is small. Batch reactors are well suited for producing small quantities of material or for producing several different products from one piece of equipment. Consequently they find extensive use in the pharmaceutical and dyestuff industries and in the production of certain specialty chemicals where such flexibility is desired. When rapid fouling is encountered or contamination of fermentation cultures is to be avoided, batch operation is preferable to continuous processing because it facilitates the necessary cleaning and sanitation procedures. 

During rotary evaporation of solvent (from an ethyl acetate extract of a fermentation culture) at 55°C/50 mbar, the flask exploded. (It seems likely that some unsuspected peroxidised material may have been present in the extract, or perhaps the flask was scratched or cracked, and imploded [1].) Several fires and explosions suggest that ethyl acetate may be a worse generator of static electricity than its measured conductivity would indicate [2],... 

Pentostatin Nipent, deoxycoformycin) is a purine isolated from fermentation cultures of the microbe Streptomyces antibioticus. Its mechanism of action involves inhibition of the enzyme adenosine deaminase, which plays an important role in purine salvage pathways and DNA synthesis. The resulting accumulation of deoxyadenosine triphosphate (dATP) is highly toxic to lymphocytes. 

Fermentation. The juice should be inoculated with an actively fermenting culture of one of the selected strains of S. fermentati. Such yeasts may be obtained from winery supply houses as pure cultures which must be multiplied to obtain enough inoculum for the large fermentation or as dried yeast which may be added directly to the juice. Alternatively, the juice may be fermented dry with one of the standard, non-film-forming yeasts, and then the dry white wine may be inoculated... 

Mitomycin C, 1, is a potent antitumor antibiotic discovered by Japanese scientists in fermentation cultures of Streptomyces caespitosus. It has been described as "small, fast and deadly (but very selective)" and has an extraordinary ability to crosslink the complementary strands of the DNA double helix with high efficiency and absolute specificity. It is so lethal that one crosslink per genome is sufficient to cause death of a bacterial cell. Mitomycin C, which is widely used clinically as an antitumor drug, does not react with DNA, but enzymatic reduction of the quinone induces a cascade of transformations which results, ultimately, in formation of the DNA crosslink 2. 

Owing to the low concentration of soluble oxygen in aqueous media (8 mM or 32 mg L-1 at 25 °C) oxygen is often the limiting component in the fermentation. Therefore, the amount of oxygen required to be transferred into a fermentation culture for the desired cell growth and product formation has to be determined. 

Mycophenolic acid (Figure 3.36) is produced by fermentation cultures of the fungus Penicillium brevicompactum. It has been known for many years to have antibacterial, antifungal, antiviral, and antitumour properties. It has recently been introduced into medicine as an immunosuppressant drug, to reduce the incidence of rejection of transplanted organs, particularly kidney and heart transplants. It is formulated as the /V-morpholinoethyl ester mycophenolate mofetil (Figure 3.37), which is metabolized after ingestion to mycophenolic... 

The pH of the medium thus obtained is adjusted to 7.20 with concentrated sodium hydroxide solution (400 cc). The medium is then sterilised by the passage of steam at 122°C for 40 minutes. After cooling, the volume of the broth is 500 liters and the pH is 6.75. It is then seeded with 50 liters of the culture from the 170 liter fermentation vessel. Culture is carried out at 28°C for 67 hours with agitation and aeration with sterile air. The pH of the medium is then 7.40 and the volume of the fermentation culture is 520 liters. The quantitiy of antibiotic present in the medium is 29 p/cc. 

When the hydroxylation reaction is complete, the reaction product must be recovered from the fermentation culture. The product is dissolved or suspended in the culture medium and can be isolated from the whole broth or from the supernatant after removal of the biomass by filtration, if necessary with a filter aid, or by centrifugation1. Thorough washing of the separated biomass with a buffer or water is advisable as a significant amount of the product might be contained in the solid phase. 

The cyciomaitodextrins (a-CD, -CD, and y-CD) can be selectively obtained from a fermentation culture or an enzyme digest of cyclomaltodextrin glucanotransferase reaction with solubilized starch. The majority of the cyclomaltohexaose (a-CD) can be separated from cycloma-Itoheptaose (/3-CD) and y-CD by their selective precipitation with p-cymene from the culture supernatant or from an enzyme digest [168]. The a-CD can then be precipitated from the supernatant with cyclohexene, which is extracted with acetone to remove the cyclohexene and the a-CD can be crystallized from water or a propanol-1/water solution [169]. The p-cymene precipitates of /3-CD and y-CD are put into a water solution and /3-CD selectively precipitated from y-CD with fluorobenzene. The y-CD is then precipitated with anthracene saturated in diethyl ether. After the removal of the fluorobenzene from /3-CD with acetone or ethanol extraction, /3-CD can be crystallized from water, and after the removal of anthracene with acetone or ethanol extraction from y-CD, it can also be crystallized from water [170,171]. The selective precipitations of the cyciomaitodextrins with various organic molecules is based on the selective formation of complexes of the organic molecules with the specific sizes of the cyciomaitodextrins and the relatively hydrophobic interior cavities of the cyciomaitodextrins [166,167,168]. 

Fig. 8-91. Separation of glucose, lactose, and maltose in a fermentation culture filtrate. - Separator column CarboPac PA1 eluent 0.1 mol/ L NaOH flow rate 1 mL/min detection see Fig. 8-88 injection 50 pL sample (diluted 1 500).

Fig. 8-92. Separation of organic acids in a fermentation culture filtrate. — Separator column IonPac ICE-AS1 eluent 0.001 mol/L octanesulfonic acid flow rate 1 mL/min detection suppressed conductivity injection 50 pL sample (diluted 1 50) (A) three days after inoculation with 2 106 cells, (B) control medium (taken from [72]).

Moo-Young, M. Chisti, Y. Bioreactor design for aeration of shear-sensitive fermentation cultures. 8th International Biolotechnology Symposium Durand, G., Bobichon, L., Florent, Eds. Paris, France Societe Franfaise de Microbiologie, 1988 Vol. 1, 454-466. 

Larger quantities of initial culture may be prepared in glass fermentation vessels each containing 10 liters of the same medium and inoculated with about 5 x 10 (to the) 9 (th) conidia. Incubation is continued for 3 days at 23° C. with aeration with 6 L. of air per minute and stirring at 200 r.p.m. In order to prevent foaming, a silicone emulsion is added. The fermentation cultures thus obtained have the same characteristics as the shake cultures. 

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