Organic acid carbon sources

Fatty acids may be converted by fungi after hydrolysis by lipase. Other organic acid carbon sources would be oleic, linoleic and linolenic acids. These might also serve as foam control agents. Carbon dioxide is a possible carbon source in nature, but is not practical commercially due to low growth rates. 

In Fig. 6 carbon dioxide reactions are categorized by industrially important products. Hydrogenation reactions produce alcohols, hydrocarbon synthesis reactions produce paraffins and olefins, and amine synthesis produces methyl and higher-order amines. Hydrolysis reactions can produce alcohols and organic acids. Carbon dioxide serves as an oxygen source in the ethyl benzene to styrene reaction. It can be used in dehydrogenation and reforming reactions. 

Table VI shows the results of the three continuous fermentations completed with the r424A organism. The carbon source in the fermentation media was corn fiber hydrolysate produced by the initial hydrolysis method followed by secondary acid hydrolysis. The yeast metabolized over 60% of the total carbohydrates with a g ethanol/g carbohydrate yield between 0.50 and 0.55. The lower percentage of total carbohydrates metabolized is likely due to the continuous fermentation method, as shake flask fermentations, albeit at lower dry solids, metabolized up to 91% of the carbohydrates (unpublished data). The carbohydrate utilization will be optimized in future fermentations. The g/g yield is near theoretical, therefore the metabolized carbohydrate is converted solely to ethanol. The organic acids, ethanol and dextrose concentrations for a sample fermentation are shown in Figure 1. The ethanol concentration in the fermentor at the end of the run was 55g/L. The concentrations of the citric acid, lactic acid and glycerol increase substantially during the fermentation, which are normal byproducts of the ethanol fermentation by Saccharomyces cerevisiae. The volume of the fermentation was doubled with hydrolysate fed into the fermentor. These fermentations show that the organism can ferment the glucose and xylose from the corn fiber hydrolysate to ethanol without detoxification of the hydrolysate. The fermentation conditions were not optimized, so additional improvement in the fermentation is expected.

LebSgue, E., T. Brousse, J. Gaubicher, and C. Cougnon. Spontaneous arylation of activated carbon from aminobenzene organic acids as source of diazonium ions in mild conditions. Electrochim. Acta 88, 2013 680-687. 

A variety of shale-protective muds are available which contain high levels of potassium ions (10). The reaction of potassium ions with clay, well known to soil scientists, results in potassium fixation and formation of a less water-sensitive clay. Potassium chloride, potassium hydroxide, potassium carbonate [584-08-7] (99), tetrapotassium pyrophosphate [7320-34-5] (100), and possibly the potassium salts of organic acids, such as potassium acetate [127-08-2] (101) and formate, have all been used as the potassium source. Potassium chloride is generally preferred because of its low cost and availabihty. 

The elemental and vitamin compositions of some representative yeasts are Hsted in Table 1. The principal carbon and energy sources for yeasts are carbohydrates (usually sugars), alcohols, and organic acids, as weU as a few other specific hydrocarbons. Nitrogen is usually suppHed as ammonia, urea, amino acids or oligopeptides. The main essential mineral elements are phosphoms (suppHed as phosphoric acid), and potassium, with smaller amounts of magnesium and trace amounts of copper, zinc, and iron. These requirements are characteristic of all yeasts. The vitamin requirements, however, differ among species. Eor laboratory and many industrial cultures, a commercial yeast extract contains all the required nutrients (see also Mineral nutrients). 

In more detail the nutrient medium used may contain sources of carbon such as starch, hydrolyzed starch, sugars such as lactose, maltose, dextrose, sucrose, or sugar sources such as molasses alcohols, such as glycerol and mannitol organic acids, such as citric acid and acetic acid and various natural products which may contain other nutrient materials in addition to carbonaceous substances. 

Acidolysis is a similar weathering reaction to hydrolysis in that is used to weather minerals, but in this case the source of is not water but organic or inorganic acids. Humic and fulvic acids (discussed in Section 8.3.2), carbonic acid, nitric or sulfuric acid, and low-molecular-weight organic acids such as oxalic acid can all provide H to weather minerals. All of these acids occur naturally in soils in addition nitric and sulfuric acid can be added to soil by acid pollution. The organic acids are prevalent in the... 

In media selective for enterobacteria a surface-active agent is the main selector, whereas in staphylococcal medium sodium and lithium chlorides are the selectors staphylococci are tolerant of salt concentrations to around 7.5%. Mannitol salt, Baird-Parker (BP) and Vogel-Johnson (VJ) media are three examples of selective staphyloccocal media. Beside salt concentration the other principles are the use of a selective carbon source, mannitol or sodium pyruvate together with a buffer plus acid-base indicator for visualizing metabolic activity and, by inference, growth. BP medium also contains egg yolk the lecithin (phospholipid) in this is hydrolysed by staphylococcal (esterase) activity so that organisms are surrounded by a cleared zone in the otherwise opaque medium. The United States Pharmacopeia (1990) includes a test for staphylococci in pharmaceutical products, whereas the British Pharmacopoeia (1993) does not. 

In Figure 34.7b, the relative selectivity to byproducts such as EG and organic acids is shown (primarily acetic, lactic and glyceric acids). Not all carbon supports are equivalent, as there are a wide variety of source materials that are used in their production. Note that the highest acid selectivity is shown with the catalyst based on a graphitic carbon and on a carbon support first treated with titania. 

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