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    Relevance To The Food Industry Food Microbiology: 40 Alcaligenes

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    Alejandra López
    Alcaligenes is a genus of bacteria that can contaminate foods like dairy products, meats, and seafood during processing or storage. It produces enzymes that are useful for industry, including one that converts a byproduct to the flavor enhancer L-glutamate. It also produces the polysaccharide curdlan, which forms a stable gel and can be used as a thickener in foods. Methods to detect Alcaligenes include growth on selective media and PCR tests to differentiate it from related genera like Bordetella.

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    Relevance To The Food Industry Food Microbiology: 40 Alcaligenes

    Uploaded by

    Alejandra López
    6 views1 page
    Alcaligenes is a genus of bacteria that can contaminate foods like dairy products, meats, and seafood during processing or storage. It produces enzymes that are useful for industry, including one that converts a byproduct to the flavor enhancer L-glutamate. It also produces the polysaccharide curdlan, which forms a stable gel and can be used as a thickener in foods. Methods to detect Alcaligenes include growth on selective media and PCR tests to differentiate it from related genera like Bordetella.

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    Alcaligenes is a genus of bacteria that can contaminate foods like dairy products, meats, and seafood during processing or storage. It produces enzymes that are useful for industry, including one that converts a byproduct to the flavor enhancer L-glutamate. It also produces the polysaccharide curdlan, which forms a stable gel and can be used as a thickener in foods. Methods to detect Alcaligenes include growth on selective media and PCR tests to differentiate it from related genera like Bordetella.

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    6 views1 page

    Relevance To The Food Industry Food Microbiology: 40 Alcaligenes

    Uploaded by

    Alejandra López
    Alcaligenes is a genus of bacteria that can contaminate foods like dairy products, meats, and seafood during processing or storage. It produces enzymes that are useful for industry, including one that converts a byproduct to the flavor enhancer L-glutamate. It also produces the polysaccharide curdlan, which forms a stable gel and can be used as a thickener in foods. Methods to detect Alcaligenes include growth on selective media and PCR tests to differentiate it from related genera like Bordetella.

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    40 Alcaligenes

    the sole carbon source, thus reducing the cost of providing an hormone tumor necrosis factor (TNF). TNF normally is
    outside substrate. Work has also been done to develop Ralstonia involved in the host immune response, but in some disease
    as biosensors for heavy metals, by fusing reporter genes to states, a rise in the hormone is observed, and this causes
    those normally expressed in the presence of metals. problems such as inflammation and endotoxic shock. Curdlan
    sulfate has been found to prevent exaggerated levels of TNF
    expression, retaining the beneficial action of the hormone
    Relevance to the Food Industry without the side effects.
    Enzymatic Production of Amino Acids
    L-Glutamate is used to enhance the flavor of foods, particularly Food Microbiology
    as the monosodium salt found in fermented sauces, such
    as soy. It is produced commercially by fermentation of In the field of food science, Alcaligenes is recognized as
    several species of bacteria. During the fermentation process, a a potential contaminant of dairy products, meats, and seafood.
    significant amount of a flavorless by-product, pyroglutamate This is a particular concern in the dairy industry, because food
    (5-oxoproline), is produced. 5-Oxoprolinase is an enzyme that items (milk especially) can be kept under refrigeration for
    converts 5-oxoproline back into L-glutamate in an adenosine extended lengths of time. Alcaligenes spp., among others, orig-
    triphosphate (ATP)–dependent reaction. The enzyme is ubiq- inate in milk samples during processing. Once introduced, they
    uitous in nature, but recently a non-ATP-utilizing derivative can grow on prolonged storage under refrigeration, even
    was found in a strain of A. faecalis. The enzyme may find though optimum growth occurs at 20–30  C. These psychro-
    practical use in the food industry for increasing yields of trophic organisms can give off-flavors to milk and reduce its
    L-glutamate. keeping quality, if the storage time before sterilization was long
    L-Lysine is an essential amino acid and a common dietary enough to allow for bacterial growth.
    supplement. In one production method, a combination of Methods for the enumeration of psychrotrophic organisms
    chemical and enzymatic reactions is used to synthesize the have been developed, but there is no accepted standard
    amino acid. A racemic mixture of the cyclic lysine derivative d,l methodology due to the diverse nature of dairy products. The
    a-amino-b-caprolactam is synthesized chemically. The race- primary emphasis is on keeping bacterial levels low, and not on
    mate is treated with a hydrolase from Candida lumicole, which identification.
    produces L-lysine from the L-isomer. The remaining D-isomer is
    racemized by a-amino-b-caprolactam racemase from A. faecalis,
    and the process is repeated until all the material is converted Detection Methods
    into L-lysine.
    The genera Alcaligenes and Bordetella have been shown to be
    closely related on the basis of 16S rRNA sequence, fatty acid
    Curdlan
    composition, and biochemical properties. Bordetella pertussis
    In stationary phase growth, A. faecalis secretes an exopoly- and Bordetella parapertussis, the causative agents of whooping
    saccharide composed of linear, unbranched D-glucose mole- cough, are isolated from human samples, whereas Bordetella
    cules in a b-1,3 glycosidic linkage. This form of polysaccharide bronchiseptica and Bordetella avium are animal and bird path-
    is synthesized by several bacterial species and is known by the ogens, respectively. Recently, two new species, Bordetella hinzii
    common name curdlan. Synthesis of curdlan is believed to and Bordetella holmesii, have been isolated from human blood
    occur through the polymerization of UDP-glucose units, and and are the only members of the genus not associated with
    two loci involved in curdlan synthesis have been cloned from respiratory infections. Alcaligenes faecalis and both subspecies
    A. faecalis. Curdlan has potential as a food additive and may of A. xylosoxidans can be found as saprophytic inhabitants of
    even have medical applications. human and animal intestinal tracts and are sources of noso-
    The property of curdlan that has the most promise in comial infection. Although not usually pathogenic, they
    regard to the food industry is the ability of the polysaccharide may be opportunistic invaders in a compromised host.
    to form a stable gel. In aqueous solution, curdlan is insoluble, Therefore, it is critical to be able to distinguish confidently
    but it becomes soluble upon heating. Increasing the pH or between the two genera when dealing with veterinary or
    additional heating of a curdlan solution causes a change of clinical isolates.
    phase to a solid gel. This change is the result of the previously Several types of solid media, primarily Bordet–Gengou
    disordered glucan chains, assuming an ordered triple helical agar, have been developed for the isolation of bordetellae.
    structure. The gel exhibits stability across a wide pH range, Alcaligenes spp. will grow on some of these, but they may be
    and retains its physical properties on freezing and thawing. distinguished by their colony morphology. Rapid and sensi-
    Curdlan currently is used in Japan as a food stabilizer and tive polymerase chain reaction (PCR) tests have been devel-
    thickener. oped to distinguish between B. pertussis, B. parapertussis,
    Curdlan also exhibits properties that may prove useful in and B. bronchiseptica once initial characterization based on
    a clinical setting. A sulfated form of the polysaccharide has biochemical tests has been performed. Some of the properties
    been shown to prevent human immunodeficiency virus from distinguishing Bordetella spp. from Alcaligenes spp. are listed
    binding to the CD4 receptor of T cells in vitro. Clinical trials are in Table 1.
    under way to demonstrate in vivo effectiveness. Certain viral Multidrug resistance is common in many bacterial genera,
    and bacterial infections are known to cause a rise in levels of the and these organisms can rapidly spread throughout the world,

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