Fermentation products ratio

Blaine, R.K. Van Lanen, J.H. Application of waste-to-product ratios in fermentation industries. Biotech. Bioeng. 1962, IV, 129-138. 

Some fermentation broths are non-Newtonian due to the presence of microbial mycelia or fermentation products, such as polysaccharides. In some cases, a small amount of water-soluble polymer may be added to the broth to reduce stirrer power requirements, or to protect the microbes against excessive shear forces. These additives may develop non-Newtonian viscosity or even viscoelasticity of the broth, which in turn will affect the aeration characteristics of the fermentor. Viscoelastic liquids exhibit elasticity superimposed on viscosity. The elastic constant, an index of elasticity, is defined as the ratio of stress (Pa) to strain (—), while viscosity is shear stress divided by shear rate (Equation 2.4). The relaxation time (s) is viscosity (Pa s) divided by the elastic constant (Pa). 

TABLE 14.11 Net Energy Production Ratios of Fermentation Ethanol Production from Com ... 

In avermectin Bl, there is a double bond between C-22 and C-23, whereas in avermectin B2 R OH. The product ratio of B2 to Bl is 1.6 1. Since the Bl analog is much more effective as an antiparasite, there is a desire to improve the B1 B2 ratio, which can be achieved by a dehydratase domain [88, 89]. Its directed evolution and mutant screening led to a mutant giving an excellent fermentation titer of Bl B2 = 1 0.07 [90, 91]. As a result of understanding the biosynthesis, pathway engineering, and directed evolution, a biologically superior new product, doramectin (Dectomax ), was evolved from a mixture of eight natural products. 

Fig. 29. a Measured [77] and b simulated final product ratios of acetoin/butanediol as a function of specific power input during fermentation... 

As seen from Equ. 6.155, if Prf > Pcstr f then the productivity ratio jRp > 1. Thus, by suitable choice of operating conditions for Fp > Fg so that Fp is maximized while Prp > Pcstr is maintained, about 10 times greater ethanol productivity was experimentally found in the rotor fermenter from a CSTR, thus illustrating the advantage of membrane reactor operation. 

Molasses is used as the feedstock for a number of industrial fermentations. AVhen the sugars have been fermented and the fermentation products removed, there is a residue rich in nitrogen-containing substances and ash. This is partially dried to give a material known as condensed molasses solubles (CMS), which contains about 350 g of crude protein per kilogram of DM.The CMS is then mixed with molasses in the ratio 20 80 to give a protein-fortified food. 

Typical for the propionic acid fermentation is the formation of identical fermentation products from Ce-, C5-, C4- and Cs-compounds. The ratio of products may differ, depending to a large extent on the degree of oxidation of the utilized carbon source. The ratio of propionic to acetic acid in glycerol medium was found to be 2 1, in lactate medium it was 1 1.5, and in pyruvate medium it was 1 2 (Vorobjeva, 1958a). Utilization of pyruvate resulted in the production of acetic acid with a constant rate (Vorobjeva, 1958b). The yield of propionic acid was twofold lower, and after four days it was almost unchanged (Fig. 3.6). No equimolarity between the acetate and CO2... 

Quantitatively, the product ratios are similar when glycerol, erythritol, adonitol or mannitol are fermented (Wood and Leaver, 1953). The same type of radioactive labeling (by CO2) is found in products arising from the fermentation of C3- and Ce-substrates. These data show that there are no separate mechanisms for C4- and Cs-compounds. 

The anaerobic breakdown of cotton has also been considered as a method to produce volatile fatty acids and methane [41]. When the pH of a growth medium that contained cotton fibers as the carbon and energy source for a methanogenic consortium was adjusted to different initial values, Tukenmez et a/. [41] observed that the amounts of fermentation products were different. The molar ratios of acetic, propionic, and butyric and methane were altered in this maimer, suggesting that processes for producing specific fermentation products from cotton could be developed. 

Jain, M.K., and Zeikus, J.G. (1997) Environmental and physiological factors affecting the succinate product ratio during carbohydrate fermentation by Tictinohacillus sp. 130Z. Arch. Microbiol., 167, 332-342. 

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