Burkholderia cenocepacia
Burkholderia cenocepacia | |
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Electron micrograph of Burkholderia cepacia | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Pseudomonadota |
Class: | Betaproteobacteria |
Order: | Burkholderiales |
Family: | Burkholderiaceae |
Genus: | Burkholderia |
Species: | B. cenocepacia
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Binomial name | |
Burkholderia cenocepacia Vandamme et al. 2003
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Burkholderia cenocepacia is a
Taxonomy
Within the Burkholderia genus, the Burkholderia cepacia complex contains over 20 related species that cause
Microbiology
The strong environmental protection response of B. cenocepacia is attributed to the biofilm formed by groups of the organism.
Genome
B. cenocepacia's genome consists of three circular chromosomes and one plasmid. Chromosome 1 contains 3.87 Mb, chromosome 2 contains 3.22 Mb, and chromosome 3 contains 0.88 Mb. The plasmid is approximately 0.09 Mb.[16] Chromosome 3 has also been characterized as a large plasmid, or megaplasmid (pC3); unlike chromosomes 2 and 3, it does not contain essential housekeeping genes, instead coding for accessory functions such as virulence and resistance to stress.[17][18] In addition to the multireplicon structure, the genome contains several insertion sequences and can rapidly mutate during infections, which contribute to B. cenocepacia's unique adaptability and ability to acquire diverse catabolic functions.[19][20]
Environments
Burkholderia cenocepacia has been found to thrive in primarily microaerophilic conditions, which consist of little to no oxygen.[21] Experimental studies conducted on the growth of B. cenocepacia in environments akin to the human lungs demonstrated the pathogen's increased success in microaerophilic environments over aerophilic settings.[21] In environments with little available iron such as the lungs of a cystic fibrosis patient, Burkholderia cenocepacia secretes siderophores, molecules that bind to iron and transport them to the bacteria.[22] Out of the four types of siderophores produced by the Bcc, B. cenocepacia produces three: ornibactin, pyochelin, and salicylic acid (SA). Ornibactin is the most important iron uptake system and can sustain the bacteria in an iron-deficient environment even without the production of functioning pyochelin or SA.[23]
B. cenocepacia has been demonstrated to colonize an array of ecological niches with diverse lifestyles. The ability to utilize a wide range of carbon sources accompanies the ability of Bcc species to be efficient with plant-growth promotion, bioremediation, and biocontrol.[12][24] High potential of Bcc species, including B. cenocepacia, as a biocontrol of plant-growth promoting agents has been demonstrated; however, the mechanisms that support this are not known.[12] In a bioremediation context, various Bcc strains are suggested to hold high potential to remediate environments contaminated with toxic compounds, including halogenated compounds.[12]
In addition, B. cenocepacia has been found to exist in the rhizosphere, plants, soil, water, and animals.
Quorum sensing
One kind of cell-to-cell communication employed by B. cenocepacia is quorum sensing, which is the detection of fluctuations in cell density and usage of this information to regulate functions such as the formation of biofilms. Like other Gram-negative bacteria, B. cenocepacia produces acyl-homoserine lactones (AHLs), signaling molecules that in members of the Burkholderia cepacia complex specifically are encoded by two systems–the CepIR system, which is highly conserved in the Bcc, and the CciIR system.[26] The two AHL-mediated QS systems, CepIR and CciIR, regulate each other; the CepR protein is required for the transcription of the cciIR operon, while the CciR protein represses transcription of cepI. The CciIR system can also negatively regulate the CepIR system through the production of C6-HSL, a type of AHL produced primarily by CciI proteins that inhibits the activity of CepR proteins.[26][27] The bacterium also uses cis-2-dodecenoic acid signals, which are known as Burkholderia diffusible signal factors (BDSF) because they were first identified in Burkholderia cenocepacia.[28]
Motility
Burkholderia cenocepacia has the ability to swim and swarm inside the body. It has a polar flagella and produces a surfactant. These characteristics are necessary for the species to have motility in an agar medium. The surfactant produced by Burkholderia cenocepacia allows other pathogenic bacteria in the lungs to have motility. This means that the presence of Burkholderia cenocepacia is necessary for swarms of bacteria to coexist and cooperate in the lungs.[29]
Pathogenicity
Burkholderia cenocepacia is an
See also: Burkholderia thailandensis sRNA
Antibiotic resistance
The structural factors that contribute to the antibiotic resistance of B. cenocepacia include: an impermeable outer membrane, an
Virulence
Virulence in Burkholderia cenocepacia is widely attributed to biofilm formation, siderophore production, and QS signaling - each of which affect how the species adapts in various environmental conditions.[22] B. cenocepacia's ability to adapt to host environments contributes to chronic opportunistic infections and bacterial persistence.[19] Several strains are noted as "epidemic strains" due to increased transmission capability and patient-to-patient transmission.[12] The ET12 strain was found to have a "cable pilus," which enables greater adhesion of bacteria to epithelial cells.[12]
In human airway epithelial cells, the invasion pathway utilized by the BC-7 strain of B. cenocepacia is largely the result of the strain's biofilm formation.[42] In general, both environmental and clinical strains of B. cenocepacia are able to form biofilms; however, the ability to do so is greater in clinical strains.[43] The H111 strain of Burkholderia cenocepacia forms biofilms on pea roots, for example.[44] Quorum signaling (QS) affects the ability of B. cenocepacia to develop biofilms, in addition to the motility abilities.[45] In addition, quorum signaling controls a variety of cellular processes, such as extracellular proteases, polygalacturonase, and the production of siderophores.[45]
Cystic fibrosis
Burkholderia cenocepacia is one of over twenty bacteria in the Burkholderia cepacia complex (Bcc), and among these species, it is a dominant bacteria associated with
Applications
Biotechnology
Given the opportunistic nature of the Bcc complex and B. cenocepacia, the severity of respiratory infections is considered to be a significant conflict for applications in biotechnology.[12]
Agriculture
To increase soil health,
References
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It is recognized as an opportunistic human pathogen causing lung infections in immunocompromised individuals, especially in cystic fibrosis patients, with significant mortality and morbidity
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- ^ "The powerhouses inside cells have been gene-edited for the first time". New Scientist. 8 July 2020. Retrieved 12 July 2020.
- ^ McRae M (10 July 2020). "For The First Time, Scientists Find a Way to Make Targeted Edits to Mitochondrial DNA". Science Alert.
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External links
- "Burkholderia cenocepacia". NCBI Taxonomy Browser. 95486.
- Type strain of Burkholderia cenocepacia at BacDive - the Bacterial Diversity Metadatabase