Acetic acid bacteria

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Acetic acid bacteria (AAB) are a group of Gram-negative bacteria which oxidize sugars or ethanol and produce acetic acid during fermentation. [1] The acetic acid bacteria consist of 10 genera in the family Acetobacteraceae. [1] Several species of acetic acid bacteria are used in industry for production of certain foods and chemicals. [1]

Contents

Description

All acetic acid bacteria are rod-shaped and obligate aerobes. [1] Acetic acid bacteria are airborne and are ubiquitous in nature. They are actively present in environments where ethanol is being formed as a product of the fermentation of sugars. They can be isolated from the nectar of flowers and from damaged fruit. Other good sources are fresh apple cider and unpasteurized beer that has not been filter sterilized. In these liquids, they grow as a surface film due to their aerobic nature and active motility. Fruit flies or vinegar eels are considered common vectors in the propagation of acetic acid bacteria. [2]

The growth of Acetobacter in wine can be suppressed through effective sanitation, by complete exclusion of air from wine in storage, and by the use of moderate amounts of sulfur dioxide in the wine as a preservative. [3]

Metabolism

Vinegar is produced when acetic acid bacteria act on alcoholic beverages such as wine. Specific oxidation reactions occur through oxidative fermentation, which creates vinegar as a byproduct. In the biotechnological industry, these bacteria's oxidation mechanism is exploited to produce a number of compounds such as l-ascorbic acid, dihydroxyacetone, gluconic acid, and cellulose. [4] Besides food industry, some acetic acid bacteria are used as biocatalysts for the industrial production of compounds. They are used as the important biocatalysts for the development of eco-friendly fermentation processes as an alternative to the chemical synthesis. [4] Some genera, such as Acetobacter, can oxidize ethanol to carbon dioxide and water using Krebs cycle enzymes. Other genera, such as Gluconobacter, do not oxidize ethanol, as they do not have a full set of Krebs cycle enzymes. As these bacteria produce acid, they are usually acid-tolerant, growing well below pH 5.0, although the pH optimum for growth is 5.4-6.3. Acetobacter xylinum is able to synthesize cellulose, [5] something normally done only by plants.

Related Research Articles

<span class="mw-page-title-main">Vinegar</span> Liquid consisting mainly of acetic acid and water

Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains from 5% to 8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to ethanol using yeast, and ethanol to acetic acid using acetic acid bacteria. Many types of vinegar are made, depending on source materials. The product is now mainly used in the culinary arts as a flavorful, acidic cooking ingredient, or in pickling. Various types are used as condiments or garnishes, including balsamic vinegar and malt vinegar.

<span class="mw-page-title-main">Mother of vinegar</span> Biofilm formed on fermenting alcoholic liquids

Mother of vinegar is a biofilm composed of a form of cellulose, yeast, and bacteria that sometimes develops on fermenting alcoholic liquids during the process that turns alcohol into acetic acid with the help of oxygen from the air and acetic acid bacteria (AAB). It is similar to the symbiotic culture of bacteria and yeast (SCOBY) mostly known from production of kombucha, but develops to a much lesser extent due to lesser availability of yeast, which is often no longer present in wine/cider at this stage, and a different population of bacteria. Mother of vinegar is often added to wine, cider, or other alcoholic liquids to produce vinegar at home, although only the bacteria is required, but historically has also been used in large scale production.

<span class="mw-page-title-main">Cellular respiration</span> Process to convert glucose to ATP in cells

Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor, such as oxygen, to drive the bulk production of adenosine triphosphate (ATP), which contains energy. Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to convert chemical energy from nutrients into ATP, and then release waste products.

<span class="mw-page-title-main">Kombucha</span> Fermented tea beverage

Kombucha is a fermented, lightly effervescent, sweetened black tea drink commonly consumed for its purported health benefits. Sometimes the beverage is called kombucha tea to distinguish it from the culture of bacteria and yeast. Juice, spices, fruit or other flavorings are often added.

<span class="mw-page-title-main">Winemaking</span> Production of wine

Winemaking or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. The science of wine and winemaking is known as oenology. A winemaker may also be called a vintner. The growing of grapes is viticulture and there are many varieties of grapes.

Acetobacter is a genus of acetic acid bacteria. Acetic acid bacteria are characterized by the ability to convert ethanol to acetic acid in the presence of oxygen. Of these, the genus Acetobacter is distinguished by the ability to oxidize lactate and acetate into carbon dioxide and water. Bacteria of the genus Acetobacter have been isolated from industrial vinegar fermentation processes and are frequently used as fermentation starter cultures.

Acetobacteraceae is a family of Gram-negative bacteria, belonging to the order Rhodospirillales, class Alphaproteobacteria. Two distinct clades are recognized. The acetic acid bacteria and a more heterogeneous group including acidophilic and phototrophic bacteria. The type genus is Acetobacter. Ten genera from Acetobacteraceae make up the acetic acid bacteria.

<span class="mw-page-title-main">Malolactic fermentation</span> Process in winemaking

Malolactic conversion is a process in winemaking in which tart-tasting malic acid, naturally present in grape must, is converted to softer-tasting lactic acid. Malolactic fermentation is most often performed as a secondary fermentation shortly after the end of the primary fermentation, but can sometimes run concurrently with it. The process is standard for most red wine production and common for some white grape varieties such as Chardonnay, where it can impart a "buttery" flavor from diacetyl, a byproduct of the reaction.

Acidogenesis is the second stage in the four stages of anaerobic digestion:

A wine fault is a sensory-associated (organoleptic) characteristic of a wine that is unpleasant, and may include elements of taste, smell, or appearance, elements that may arise from a "chemical or a microbial origin", where particular sensory experiences might arise from more than one wine fault. Wine faults may result from poor winemaking practices or storage conditions that lead to wine spoilage.

Microbial metabolism is the means by which a microbe obtains the energy and nutrients it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other based on metabolic characteristics. The specific metabolic properties of a microbe are the major factors in determining that microbe's ecological niche, and often allow for that microbe to be useful in industrial processes or responsible for biogeochemical cycles.

Acidophiles or acidophilic organisms are those that thrive under highly acidic conditions. These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukarya.

<span class="mw-page-title-main">SCOBY</span> Symbiotic culture of bacteria and yeast

Symbiotic culture of bacteria and yeast (SCOBY) is a culinary symbiotic fermentation culture (starter) consisting of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast which arises in the preparation of sour foods and beverages such as kombucha. Beer and wine also undergo fermentation with yeast, but the lactic acid bacteria and acetic acid bacteria components unique to SCOBY are usually viewed as a source of spoilage rather than a desired addition. Both LAB and AAB enter on the surface of barley and malt in beer fermentation and grapes in wine fermentation; LAB lowers the pH of the beer/wine while AAB takes the ethanol produced from the yeast and oxidizes it further into vinegar, resulting in a sour taste and smell. AAB are also responsible for the formation of the cellulose SCOBY.

<span class="mw-page-title-main">Acids in wine</span>

The acids in wine are an important component in both winemaking and the finished product of wine. They are present in both grapes and wine, having direct influences on the color, balance and taste of the wine as well as the growth and vitality of yeast during fermentation and protecting the wine from bacteria. The measure of the amount of acidity in wine is known as the “titratable acidity” or “total acidity”, which refers to the test that yields the total of all acids present, while strength of acidity is measured according to pH, with most wines having a pH between 2.9 and 3.9. Generally, the lower the pH, the higher the acidity in the wine. There is no direct connection between total acidity and pH. In wine tasting, the term “acidity” refers to the fresh, tart and sour attributes of the wine which are evaluated in relation to how well the acidity balances out the sweetness and bitter components of the wine such as tannins. Three primary acids are found in wine grapes: tartaric, malic, and citric acids. During the course of winemaking and in the finished wines, acetic, butyric, lactic, and succinic acids can play significant roles. Most of the acids involved with wine are fixed acids with the notable exception of acetic acid, mostly found in vinegar, which is volatile and can contribute to the wine fault known as volatile acidity. Sometimes, additional acids, such as ascorbic, sorbic and sulfurous acids, are used in winemaking.

<span class="mw-page-title-main">Acetic acid</span> Colorless and faint organic acid found in vinegar

Acetic acid, systematically named ethanoic acid, is an acidic, colourless liquid and organic compound with the chemical formula CH3COOH. Vinegar is at least 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water and other trace elements.

<span class="mw-page-title-main">Traditional balsamic vinegar</span> Type of vinegar originating in Italy

Traditional balsamic vinegar is a type of balsamic vinegar produced in Modena and the wider Emilia Romagna region of Italy. Unlike inexpensive "Balsamic Vinegar of Modena" (BVM), Traditional Balsamic Vinegar (TBV) is produced from cooked grape must, aged at least 12 years, and protected under the European Protected Designation of Origin (PDO) system, fetching higher prices. Although the names are similar, TBV and the inexpensive imitation BVM are very different.

<span class="mw-page-title-main">Bacterial cellulose</span> Organic compound

Bacterial cellulose is an organic compound with the formula (C
6
H
10
O
5
)
n
produced by certain types of bacteria. While cellulose is a basic structural material of most plants, it is also produced by bacteria, principally of the genera Acetobacter, Sarcina ventriculi and Agrobacterium. Bacterial, or microbial, cellulose has different properties from plant cellulose and is characterized by high purity, strength, moldability and increased water holding ability. In natural habitats, the majority of bacteria synthesize extracellular polysaccharides, such as cellulose, which form protective envelopes around the cells. While bacterial cellulose is produced in nature, many methods are currently being investigated to enhance cellulose growth from cultures in laboratories as a large-scale process. By controlling synthesis methods, the resulting microbial cellulose can be tailored to have specific desirable properties. For example, attention has been given to the bacteria Komagataeibacter xylinum due to its cellulose's unique mechanical properties and applications to biotechnology, microbiology, and materials science. Historically, bacterial cellulose has been limited to the manufacture of Nata de coco, a South-East Asian food product. With advances in the ability to synthesize and characterize bacterial cellulose, the material is being used for a wide variety of commercial applications including textiles, cosmetics, and food products, as well as medical applications. Many patents have been issued in microbial cellulose applications and several active areas of research are attempting to better characterize microbial cellulose and utilize it in new areas.

<i>Acetobacter aceti</i> Species of bacterium

Acetobacter aceti is a Gram-negative bacterium that moves using its peritrichous flagella. Louis Pasteur proved it to be the cause of conversion of ethanol to acetic acid in 1864. It is a benign microorganism which is present everywhere in the environment, existing in alcoholic ecological niches which include flowers, fruits, and honey bees, as well as in water and soil. It lives wherever sugar fermentation occurs. It grows best in temperatures that range from 25 to 30 degrees Celsius and in pH that ranges from 5.4 to 6.3. For a long time it has been used in the fermentation industry to produce acetic acid from alcohol. Acetobacter aceti is an obligate aerobe, which means that it requires oxygen to grow.

Komagataeibacter xylinus is a species of bacteria best known for its ability to produce cellulose, specifically bacterial cellulose.

<span class="mw-page-title-main">Wine preservatives</span> Food preservation

Wine preservatives are used to preserve the quality and shelf life of bottled wine without affecting its taste. Specifically, they are used to prevent oxidation and bacterial spoilage by inhibiting microbial activity.

References

  1. 1 2 3 4 Raspor P; Goranovic D (2008). "Biotechnological applications of acetic acid bacteria". Critical Reviews in Biotechnology . 28 (2): 101–124. doi:10.1080/07388550802046749. PMID   18568850. S2CID   86778592.
  2. Solieri, Laura; Giudici, Paolo (2008-12-16). "Chapter 5". Vinegars of the World. doi:10.1007/978-88-470-0866-3. ISBN   978-88-470-0865-6. Archived from the original on 2019-09-25. Retrieved 28 May 2016.
  3. "Sulfur Dioxide: Science behind this anti-microbial, anti-oxidant". Practical Winery & Vineyard Journal. February 2009. p. 4. Retrieved 28 May 2016.
  4. 1 2 Mamlouk, D. & Gullo, M. Acetic Acid Bacteria: Physiology and Carbon Sources Oxidation. Indian Journal of Microbiology 53, 377–384 (2013).
  5. Kaushal, R.; Walker, T. K. (May 1951). "Formation of cellulose by certain species of Acetobacter". Biochem. J. 48 (5): 618–621. doi:10.1042/bj0480618. PMC   1275385 . PMID   14838912.

Further reading