Butyric acid microorganisms

Aliphatic acids such as butyric acid have been previously implicated as being allelopathic compounds (46, 47, 23). Chou and Patrick (23) isolated butyric acid from soil amended with rye and showed that it was phytotoxic. Hydroxy acids have also been shown to possess phytotoxic properties (48) but have not been implicated in any allelopathic associations. Since SHBA is a stereo isomer, and the enantiomer was not identified because of impurity, all bioassays were run using a racemic mixture. The D-(-) stereo isomer of SHBA has been isolated from both microorganisms and root nodules of legumes and is suspected to be a metabolic intermediate in these systems (49). It is likely that only one enantiomer was present in the extract therefore, the true phytotoxic potential of this compound awaits clarification of the phytotoxicity of the individual enantiomers. 

Microorganisms have also been developed to produce alternative products, such as lactic acid [65], propane-1,3-diol [67], 3-hydroxypropionic acid [68], butane-2,3-diol [69] and numerous other intermediates. For instance, bacteria such as the Clostridium acetobutylicum ferment free sugars to C4 oxygenates such as butyric acid or butanol. They form the C4 oxygenates by Aldol condensation of the acetaldehyde intermediates. The Weizmann process exploits this property to ferment starch feedstock anaerobically at 37 °C to produce a mixture of w-butanol, acetone and ethanol in a volume ratio of 70 25 5 [3],... 

The waste products of a home include paper, containers, tin cans, aluminum cans, and food scraps, as well as sewage. The waste products of industry and commerce include paper, wood, and metal scraps, as well as agricultural waste products. Biodegradable wastes, such as paper fines and industrial biosludge, into mixed alcohol fuels (e g., isopropanol, isobutanol, isopentanol). The wastes are first treated with lime to enhance reactivity. Then, they are converted to volatile fatly acids (VFAs) such as acetic acid, propionic acid, and butyric acid, using a mixed culture of microorganisms derived from cattle rumen or anaerobic waste treatment facihties. 

These short-chain fatty acids are acetic, butyric, lactic and propionic acids, also known as volatile fatty acids, VFA. They are produced from fermentation of carbohydrate by microorganisms in the colon and oxidised by colonocytes or hepatocytes (see above and Chapter 4). Butyric acid is activated to produce butyryl-CoA, which is then degraded to acetyl-CoA by P-oxidation acetic acid is converted to acetyl-CoA for complete oxidation. Propionic acid is activated to form propionyl-CoA, which is then converted to succinate (Chapter 8). The fate of the latter is either oxidation or, conversion to glucose, via glu-coneogenesis in the liver. 

Respiration inhibition kinetics analysis (RIKA) involves the measurement of the effect of toxicants on the kinetics of biogenic substrate (e.g., butyric acid) removal by activated sludge microorganisms. The kinetic parameters studied are max> the maximum specific substrate removal rate (determined indirectly by measuring the maximum respiration rate), and Ks, the half-saturation coefficient [19]. The procedure consists of measuring with a respirometer the Monod kinetic parameters, Vinax and Ks, in the absence and in the presence of various concentrations of the inhibitory compound. 

The response to organic compounds depends on the assimilability by the immobilized microorganisms. Trichosporon brassicae, utilized propionic acid, n-butyric acid and ethanol. The measurement can be within 4 min using a flow cell (8). 

Although com can be adequately steeped in sterile, aqueous solutions of sulfur dioxide or sodium, magnesium or potassium bisulfite (hydrogen sulfite) in the laboratory,164-166 commercial steeping involves microorganisms. Raw com carries natural populations of bacteria, yeasts and molds which are capable of rapid multiplication in aqueous systems. Wet-millers learned early that com steeped at temperatures of 45-55°C was sweet, but that putrefaction and butyric acid or alcohol production... 

Various microorganisms under certain conditions are able to excrete intermediate products (organic acids) from or closely related to the tricarboxylic acid cycle (Fig. 3, Table 4). For example, Clostridium produces acetic acid and butyric acid, Lactobacillus and Streptococcus species produce lactic acid, Acetobacter species acetic, gluconic, and ketogluconic acids, and Pseudomonas species 2-ketogluconic and a-ketoglutaric acids. 

In a field digester these steady-state values would also be affected by the fact that most of the volatile acids and cations (NH4 ) would be generated internally with some carbon dioxide being produced by the acid-producing bacteria. Acids other than acetic are also formed, and it is of interest to compare the steady state conditions for other volatile acids with those of acetic. The formulas for converting propionic and butyric acids to microorganisms, methane, and carbon dioxide are given in Equations 32 and 33. 

Polyhydroxybutyric acid is a storage compound for excess carbon in many microorganisms (E 2.2). It may be used in the production of plastics (F 4). Acetoacetic acid, acetone, and /S-hydroxybutyric acid are excreted in the urine of people with a pathologically high blood sugar level (diabetes mellitus) (E 1). Their appearance is of diagnostic value. Butyric acid, butanol, and acetone are products of microbial fermentations. 

Hydrolyzing and fermenting microorganisms are responsible for the initial attack on polymers and monomers and produce mainly acetate and hydrogen and some amounts of volatile fatty acids (VFA) such as propionate and butyrate. Hydrolytic microorganisms lead to hydrolytic enzymes, e.g., cellulose, cellobiase, xylanase, amylase, hpase, and protease. 

Other microorganisms have different ways of metabolizing pyruvate. End products include lactic acid, butyric acid and propionic acid as well as various alcohols. Some of the reactions are considered in more detail in connection with the metabolism of plaque. 

The simple components xylose, glucuronic acid, and arabinose are rapidly fermented by rumen microorganisms with the formation of the volatile fatty acids (Heald and McNaught ), acetic, propionic, and butyric acids, with acetic acid predominating. 

The proper running of the fermentation process prevents the growth of detrimental microorganisms, such as molds, butyric acid bacteria and putrefaction-inducing bacteria. 

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