Alkaline fermentation

Ouoba, L.I., Thorsen, L., and Varnam, A.H. (2008) Enterotoxins and emetic toxins production by Bacillus cereus and other species of Bacillus isolated from Soumbala and Bikalga, African alkaline fermented food condiments. Int. J. Food Microbiol, 135 (3), 224-230. 

Urease, the enzyme responsible for the alkaline fermentation of urine, is widely distributed through the vegetable kingdom. 

The sweet water from continuous and batch autoclave processes for splitting fats contains tittle or no mineral acids and salts and requires very tittle in the way of purification, as compared to spent lye from kettle soapmaking (9). The sweet water should be processed promptly after splitting to avoid degradation and loss of glycerol by fermentation. Any fatty acids that rise to the top of the sweet water are skimmed. A small amount of alkali is added to precipitate the dissolved fatty acids and neutralize the liquor. The alkaline liquor is then filtered and evaporated to an 88% cmde glycerol. Sweet water from modem noncatalytic, continuous hydrolysis may be evaporated to ca 88% without chemical treatment. 

The most widely available yeast biomass is a by-product of the brewing industry, where the multiplication of yeast during brewing results in a surplus of ceUs. Eor every barrel (117 L) of beer brewed, 0.2—0.3 kg of yeast soHds may be recovered. In the U.S., a substantial fraction is recovered and made available about 40 x 10 kg of brewers yeast aimually. The yeast is recovered from beer by centrifuging and dried on roUer dmms or spray dryers and sold as animal feed or a pet-food supplement. It can be debittered by alkaline extraction to remove the bitter hop residues, and is then sold mainly by the health-food industry. It is available as tablets, powder, or flakes and is often fortified with additional vitamins. Distillers yeast caimot be readily separated from the fermented mash and the mixture is sold as an animal feed supplement. 

Water. The character of the water has a great influence on the character of the beer and the hardness of water (alkalinity) manifests itself by the extent of its reaction with the weak acids of the mash. Certain ions are harm fill to brewing nitrates slow down fermentation, iron destroys the colloidal stabihty of beer, and calcium ions give beer a purer flavor than magnesium or sodium ions (Table 7). 

In 1958, the microbial alkaline protease Alcalase (Novo Industries) was produced by fermentation of a strain of Bacillus licheniformis. It had high StabiHty and activity at pH 8—10, was marketed in 1961, and was incorporated into Bio 40. However, it was not until the successful marketing of the presoaking agent Biotex in 1963 that detergent manufacturers saw the tme possibiHties of enzymes. 

Several new detergent enzymes have emerged on the market (Table 1). Truly alkaline proteases, introduced in 1974 and 1982, were fermented on strains of Bacillus lentus firmus. These enzymes have a pH optimum between 9 and 11, and have taken important market shares from Alcalase. 

PTC may well provide a way of recovering valuable chemicals from the waste streams of fine chemicals plants. Krishnakumar and Sharma (1984) have shown how phenolic substances from aqueous alkaline streams can be recovered as useful, saleable substances and their content brought down to below 5 ppm in the waste streams. Even penicillin from waste liquors discharged from fermentation plants can be recovered (Lindblom and Blander, 1980). 

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. 

Recovery of alkaline protease from fermentation broth [82]... 

The synthetic value of this reaction should be mentioned. Thus, current production of 5p-steroids from As-3(i-ols, readily available and cheap starting materials, requires a preliminary Oppenauer oxidation or fermentation to the A4-3-keto derivative followed by catalytic hydrogenation under alkaline conditions, as direct catalytic hydrogenation with both heterogeneous and homogeneous systems gives only the 5a isomer. 

Secretion of the large intestine. The large intestine produces an alkaline mucus secretion, the function of which is to protect the mucosa from mechanical or chemical injury. Mucus provides lubrication to facilitate the movement of the contents of the lumen. Bicarbonate ion neutralizes the irritating acids produced by local bacterial fermentation colonic secretion increases in... 

The tetracycline which may be present is then converted to an anhydro derivative by heating in acid and is measured spectrophotometrically. Feldman et al. (84) developed the alkaline degradation method to measure CTC in fermentation mash and Spock and Katz (85) used this method to determine CTC in animal feed premixes. 

Fig. 11. Flow chart of a typical pDNA production process. After fermentation cells are harvested and lysed by addition of alkaline solution. Clarification by filtration is followed by a series of chromatographic steps. After a final 0.22 pm filtration step the purified plasmid is aliquoted and stored...

Because of fermentation processes, the luminal environment of the colon is slightly acidic at a pH value around 6.6 [2], Similar pH values can be found in the upper small intestine (pH 6.5 and pH 6.7, in the duodenum and jejunum, respectively), whereas in the ileum the pH is slightly higher at a neutral to alkaline pH value around 7.1 [2], Therefore, the slightly acidic solutions, which are generally used for maintaining physiologically relevant luminal conditions... 

In order to develop a host strain for production of a variety of subtilisin enzymes, it was first necessary to delete the endogenous alkaline and neutral proteases (72,76). The strain was then constmcted to contain the optimal combination of subtilisin regulatory genes which were compatible with the proposed fermentation and recovery process. Once this strain had been produced, the recombinant enzyme... 

Ideas regarding the mechanism of phytochemical reduction of olefins have been advanced by Fischer and Eysenbach. They also point out that just as in the case of the simple disproportionations in the course of sugar degradation (for example, the second and third forms of fermentation), saturation of the olefinic linkage is at an optimum in the weakly alkaline range, at about pH 8.5. 

The fermentation broth typically contains 20-30 mg/L of antibiotics, which is to say 30 parts per billion, and must be extracted into concentrated form using solvent extraction. The solvent extraction method was developed by Shell Oil and by Podbielniack and is based on the principle that penicillin is hydrolyzed in aqueous medium to H+ and RCOO ions. Thus, equilibrium in an acidic medium (i.e., one with low pH or high H+ concentration) is favored by the neutral RCOOH form, whereas equilibrium in an alkaline medium (i.e., one with high pH or low H+ concentration) is favored by the RCOO ionic form. The neutral form is more soluble in an organic medium, and the ionic form is more soluble in an aqueous medium. Thus, with amyl acetate as the organic solvent the partition coefficient of penicillin between solvent and water is about 100 at pH 3 and about 1 at pH 6. In the industrial process, the aqueous broth was acidified to pH 3 for the extraction into the organic solvent, and alkalized to a pH 6 for reverse extraction back into an aqueous medium. 

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