Ethanol acetic acid bacteria

Although they oxidize ethanol, acetic acid bacteria are not especially resistant to it. On average, Gluconobacter do not tolerate more than 5% ethanol, and few Acetobacter develop at above... 

Simple organic molecules Ethanol Butanol Acetone Acetic acid Lactic acid Saccharomyces cerevisiae Pachysolen tamiophilus, some Clostridium spp. Clostridium acetobutylicum, C. saccharoacetobutylicum Clostridium acetobutylicum, C. saccharoacetobutylicum Various acetic acid bacteria Lactobacillus spp. 

One of the largest groups of strictly aerobic heterotrophic bacteria, the pseudomonads (Pseudomonas and related genera), are of interest to biochemists because of their ability to oxidize organic compounds, such as alkanes, aromatic hydrocarbons, and steroids, which are not attacked by most other bacteria. Often, the number of oxidative reactions used by any one species of bacteria is limited. For example, the acetic acid bacteria that live in wine and beer obtain all of their energy by oxidation of ethanol to acetic acid ... 

The fermentative production of lactic acid from carbohydrates has repeatedly been reviewed recently [36, 41, 42]. Two classes of lactic acid producers are discerned the homofermentative lactic acid bacteria, which produce lactic acid as the sole product, and the heterofermentative ones, which also produce ethanol, acetic acid etc. [43]. Recently, the focus has been on (S)-L-lactic acid producing, homofermentative Lactobacillus ddbrueckii subspecies [42]. 

Yeasts Ethanol + carbon dioxide Acetic acid bacteria... 

Acetic acid bacteria (AAB) are known for their ability to oxidize different substrates containing ethanol into various types of vinegar (Trcek, 2005). Substrates used as energy sources include glucose, ethanol, lactate, or glycerol. Most of these compounds are not completely oxidized into COz and HzO and many metabolites, such as acetic acid, may be accumulated in the growth medium. AAB are commonly found in nature and acetic... 

Various strains of the AAB are ethanol-tolerant, and the majority of strains have been found to be able to grow at 5% v/v ethanol, and some even at 10%. Glucose tolerance has often been described in various AAB, and is frequently found in strains isolated from traditional balsamic vinegar. One of the inhibiting substances for acetic acid bacteria is high... 

Acetic acid bacteria (AAB) are known for oxidizing various ethanol-containing substrates into a variety of vinegars, but are also used for the production of some biotechnologically important products, such as sorbo se... 

Like above but contains beer and agar. Contains inter alia bile salts and neutral red indicator. Reasonably selective for brewery enterobacteria. Hafnia takes an extra day to grow at 25°C (77°F) on solid medium. Contains inter alia, ethanol and indicator (powdered chalk might be added). Suppresses most brewery microorganisms except acetic acid bacteria. 

Figure 19.3 Energy generation in acetic acid bacteria. The oxidation of ethanol leads to the release of electrons captured by quinones (QH2) in the plasma membrane of acetic acid bacteria. The transfer of electrons within the membrane can be nsed for tbe release of protons from integral membrane dehydrogenases or from membrane-associated dehydrogenases. The removal of protons by the quinol oxidases from the membrane creates a protomnotive force that can be used in the generation of ATP.

The production of vinegar involves an initial anaerobic alcoholic fermentation followed by an aerobic fermentation using acetic acid bacteria to convert the ethanol to acetic acid. The ethanol concentration is vital to the overall efficiency of the process and must be monitored regularly using procedures similar to those indicated for yeast production. 

Figure 8.1 Metabolism of ethanol by acetic acid bacteria.

It is known to mankind since prehistoric times that wine, beer, or other weak fermented liquors will become sour on exposure to the air. The underlying aerobic fermentation has been used ever since for the production of acetic acid, colloquially known as vinegar. Vinegar making, so as it is practiced by chefs around the world in the kitchen, as well as by the industry, involves a two-step process— the anaerobic yeast fermentation to yield ethanol (ref 4.1,4.2) followed by an aerobic bacterial fermentation process yielding acetic acid. Acetic acid fermentation is performed by the action of acetic acid bacteria (acetobacteraceae,AAB). AAB first oxidizes the ethanol to acetaldehyde, which is then converted to acetic acid ... 

Vinegar is produced via industrial fermentation of alcohol (ethanol) hy acetic acid bacteria. These bacteria are not welcomed by winemakers since bacteria tend to spoil wine by converting it into vinegar. The word vinegar is derived from the French words vin (wine) and egre (sour). 

Methods for degrading ribulose (n-er / Aro-pentulose) and sedoheptulose (n-aZ ro-heptulose) have been devised by Bassham and associates 46). Biological methods of degradation depending on the action of bacteria to produce small fragments such as ethanol, acetic acid, formic acid, lactic acid, etc., are of rather wide use in the sugar field. 

Considered to be spoilage microorganisms in winemaking (Drysdale and Fleet, 1988 Du Toit and Pretorius, 2002), growth of acetic acid bacteria results in oxidation of ethanol to acetic acid (the process of ace-tification). In addition, other odor- and flavor-active metabolites as well as polysaccharides including dextrans and levans may he formed (Colvin et al., 1977 Tayama et al., 1986). The latter can create problems during post-fermentation clarification and stabihty. 

Figure 3.3. Oxidation of ethanol with the formation of acetic acid by acetic acid bacteria. Adapted from Adams (1998) with the kind permission of Springer Science and Business Media.

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