Citrobacter freundii

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Citrobacter freundii
Citrobacter freundii.jpg
Scientific classification
C. freundii
Binomial name
Citrobacter freundii
(Braak 1928) Werkman and Gillen 1932 [1]

Citrobacter freundii is a species of facultative anaerobic gram-negative bacteria of the family Enterobacteriaceae. [2] The bacteria have a long rod shape with a typical length of 1–5 μm. [3] Most C. freundii cells generally have several flagella used for locomotion, but some do not and are non-motile. C. freundii is a soil organism, but can also be found in water, sewage, food and in the intestinal tracts of animals and humans. [3] The genus Citrobacter was discovered in 1932 by Werkman and Gillen. Cultures of C. freundii were isolated and identified in the same year from soil extracts. [3]

Facultative anaerobic organism organism that makes ATP by aerobic respiration if oxygen is present

A facultative anaerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent.

Gram-negative bacteria group of bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation

Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the gram-staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane.

Enterobacteriaceae family of bacteria

The Enterobacteriaceae are a large family of Gram-negative bacteria. This family is the only representative in the order Enterobacteriales of the class Gammaproteobacteria in the phylum Proteobacteria.

C. freundii is a common component of the gut microbiome of healthy humans. [4] While most strains are beneficial, there are significant phenotypic variations among strains, even those that share >99% of their genome. [5] Some rare strains of C. freundii have been associated with opportunistic nosocomial infections of the respiratory tract, urinary tract, blood, and many other normally sterile sites in immunocompromised patients. [6]

C. freundii is also commonly found to be a member of the soil microbiome. This microbe plays an important role in the nitrogen cycle in the environment. C. freundii is responsible for reducing nitrate to nitrite in the environment. [7] This conversion is an important and crucial stage in the nitrogen cycle.

Nitrogen cycle biogeochemical cycle by which nitrogen is converted into various chemical forms

The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmosphere nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.

Nitrate anion

Nitrate is a polyatomic ion with the molecular formula NO
and a molecular mass of 62.0049 u. Organic compounds that contain the nitrate ester as a functional group (RONO2) are also called nitrates.

Nitrite anion

The nitrite ion, which has the chemical formula NO
, is a symmetric anion with equal N–O bond lengths. Upon protonation, the unstable weak acid nitrous acid is produced. Nitrite can be oxidized or reduced, with the product somewhat dependent on the oxidizing/reducing agent and its strength. The nitrite ion is an ambidentate ligand, and is known to bond to metal centers in at least five different ways. Nitrite is also important in biochemistry as a source of the potent vasodilator nitric oxide. In organic chemistry the NO
group is present in nitrous acid esters and nitro compounds. Nitrite is also used in the food production industry for curing meat.

C. freundii has also been investigated for biodegradation of tannic acid used in tanneries. [7]

Biodegradation Decomposition by living organisms

Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria, fungi.

Tannic acid chemical compound

Tannic acid is a specific form of tannin, a type of polyphenol. Its weak acidity (pKa around 6) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C76H52O46, which corresponds with decagalloyl glucose, but in fact it is a mixture of polygalloyl glucoses or polygalloyl quinic acid esters with the number of galloyl moieties per molecule ranging from 2 up to 12 depending on the plant source used to extract the tannic acid. Commercial tannic acid is usually extracted from any of the following plant parts: Tara pods (Caesalpinia spinosa), gallnuts from Rhus semialata or Quercus infectoria or Sicilian Sumac leaves (Rhus coriaria).

C. freundii has the ability to grow on glycerol, and use it as its sole source of carbon and energy. The organism contains a bacterial microcompartment which is capable of processing propanediol. C. freundii creates a positive MR and negative VP test along with a positive Catalase and negative Oxidase test. C. freundii cannot hydrolyze starch, lipids, or gelatin. [8]

Glycerol chemical compound

Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in many lipids which are known as glycerides. It is widely used in the food industry as a sweetener and humectant and in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature.

Propanediol may refer to either of three isomeric organic chemical compounds:

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Lipopolysaccharide chemical compound

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