Vacuum fermentation

Apparatus A 250-mL Erlenmeyer flask, separatory funnel, apparatus for magnetic stirring, anaerobic fermentation, vacuum filtration, simple distillation, and flameless heating. 

A vertical cylindrical, and mechanical agitated pressure vessel, equipped with baffles to prevent vortex formation is the most widely used fermenter configuration. The baffles are typically one-tenth of the fermenter diameter in widtli, and are welded to supports tliat extend from the sidewall. A small space between the sidewall and the baffle enables cleaning. Internal heat transfer tube bundles can also be used as baffles. The vessels must withstand a 45 psig internal pressure and full vacuum of -14.7 psig, and comply with the ASME code. 

A selected strain o1 Streptomyces halstedii was cultivated in an aqueous nutrient medium under aerobic conditions and the resulting broth containing carbomycin antibiotics was filtered. The solutions was extracted twice at pH 6.5 with one-quarter volume of methyl isobutyl ketone. The combined extracts were concentrated to one-tenth volume under vacuum, and the antibiotics were extracted into water adjusted to a pH of about 2 with sulfuric acid. After adjusting the separated aqueous solution to pH 6.5, the antibiotic was extracted into benzene and the solution was concentrated to a small volume. Addition of hexane resulted in the separation of a solid product containing the benzene complexes of carbomycin A and carbomycin B, present in the fermentation broth. 

After the end of the fermentation (28 hours) the culture broth is filtered off by suction over a large suction filter. The mycel residue is washed with water several times. The filtrate is extracted three times, each time with 10 liters of methyl isobutyl ketone. The extract is concentrated under vacuum in a circulating evaporator and in a round flask carefully dried under vacuum. The residue is crystallized from acetone/isopropyl ether. The melting point is 157°-158°C (fermentation yield = 60%). The pure product yield obtained after a second crystallization and chromatography of the mother liquor on silica gel amounts to 53% of the theoretical. 

Figure 2.5 Possible technological solutions to bioprocess problems a) Fed-batch culture b) Continuous product removal (eg dialysis, vacuum fermentation, solvent extraction, ion exchange etc) c) Two-phase system combined with extractive fermentation (liquid-impelled loop reactor) d) Continuous culture, internal multi-stage reactor e) Continuous culture, dual-stream multi-stage reactor f) Continuous culture with biomass feedback (cell recycling). (See text for further details).

Plate filters are suitable for filtration of batch fermentation broth accumulated biomass must be cleaned periodically. A rotary dram vacuum filter is used for a continuous system. 

A fermentation broth containing Streptomyces kanamyceticus cells is filtered by a vacuum rotary filter. The feed rate is 120kg h1 each kilogram of broth contains 60g of cells. To improve filtration, filter aids are added at a rate of 10kg-h. The concentration of kanamycin in the broth is 0.05%. The filtrate is collected at a rate of 112 kg h. The concentration of kanamycin in the filtrate is 0.045%. The filter cake contains cells, and filter aid is continuously removed from the filter cloth. 

The water content in honey is generally less than 20%. Any excess of water can be removed by centrifugation or vacuum evaporation. If water is artificially added into honeys, it can cause honey fermentation. The water content in honey needs to be in a normal range such as 15.5-18.6% as recommended by the Eastern Apicultural Society of North America. 

The mash from the Streptomyces aureofaciens fermentation broth is acidified and filtered. The filtrate is adjusted to the desired pH, usually 7-8.5, and various flocculating or chelating agents may be added (e.g., vinyl acetate-maleic anhydride copolymer, sodium EDTA, ammonium oxalate, Arquad). The precipitate is (1) stirred with filter aid, filtered, stirred with HC1, refiltered, mixed with 2-ethoxyethanol, filtered, washed, and the filtrates are combined, acidified with HC1, NaCl is added, and the crystals are collected, washed with 2-ethoxyethanol, water, and ethanol, and dried (67), or (2) extracted into methyl isobutyl ketone, the extracts are combined, filtered, and acidified with HC1, and the crystals are collected and washed with water, 2-ethoxyethanol, and isopropanol, and vacuum-dried. If the crystals are greenish, they are treated with sodium hydrosulfite at pH 1.8, filtered, washed, and dried as in (1) above (68). 

Tyrothricin was obtained by acidification of the fermentation broth of Bacillus brevis to precipitate the antibiotic activity along with various proteins and then dissolving the antibiotic complex in alcohol. The alcohol was removed under vacuum, the residue was washed with ether, then redissolved in alcohol and finally reprecipitated with 1% sodium chloride5 6. 

Garrido-Femandez, A., Brenes-Balbuena, M., Garcia-Garcia, P., and Romero-Barranco, C. 2001. Problems related to fermentation brines in the table olive sector. In Osmotic Dehydration and Vacuum Impregnation Application in Food Industries (P. Fito, A. Chiralt, J.M. Barat, W.E.L. Spiess, and D. Behsnilian, eds), pp. 123-132. Technomic Publishing, Lancaster, PA. 

Since fermentation takes place in a dilute aqueous solution, the reaction continues until the alcohol concentration approaches about 14%. At higher concentrations, the process becomes self-inhibitory. By-products from starch fermentation to ethanol can include higher-molecular-weight alcohols, glycerine, and ethers. Usually no more than 10% starch is converted to these compounds. Atmospheric distillation, vacuum distillation, and membrane separation techniques can be used to recover ethanol from the final fermented product. The distillate bottoms, called stillage, are recovered as a by-product for animal feed. A biomass fermentation flow diagram is provided in FIGURE 12-2. 

In contrast to the decaffeination of coffee, which is primarily executed with green coffee, black tea has to be extracted from the fermented aromatic material. Vitzthum and Hubert have described a procedure for the production of caffeine-free tea in the German patent application, 2127642 [11]. The decaffeination runs in multi-stages. First, the tea will be clarified of aroma by dried supercritical carbon dioxide at 250 bar and 50°C. After decaffeination with wet CO2 the moist leaf-material will be dried in vacuum at 50°C and finally re-aromatized with the aroma extract, removed in the first step. Therefore, the aroma-loaded supercritical CO2 of 300 bar and 40°C will be expanded into the extractor filled with decaffeinated tea. The procedure also suits the production of caffeine-free instant tea, in which the freeze-dried watery extract of decaffeinated tea will be impregnated with the aromas extracted before. 

The substrate used in all experiments consisted of soy cake, which is the byproduct of soybean oil extraction. The cake was milled and classified (Tyler 35-60) and then stored at -10°C in vacuum packs. Fermentation was... 

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