Shewanella oneidensis

Source: Wikipedia, the free encyclopedia.

Shewanella oneidensis
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Alteromonadales
Family:
Shewanellaceae
Genus: Shewanella
Species:
S. oneidensis
Binomial name
Shewanella oneidensis
Venkateswaran et al. 1999

Shewanella oneidensis is a

Lake Oneida, NY in 1988, hence its name.[1]

Shewanella oneidensis is a

chromates
when grown anaerobically.

Name

This species is referred to as S. oneidensis MR-1, indicating "manganese reducing", a special feature of this organism. It is a common misconception to think that MR-1 refers to "metal-reducing" instead of the original intended "manganese-reducing" as observed by Kenneth H. Nealson, who first isolated the organism.

Qualities

Metal reduction

Shewanella oneidensis MR-1 belongs to a class of bacteria known as "

scanning electron microscopy and transmission electron microscopy
revealed abnormal structural protrusions resembling bacterial filaments that are thought to be involved in the metal reduction. This process of producing an external filament is completely absent from conventional bacterial respiration and is the center of many current studies.

The mechanics of this bacterium's resistance and use of heavy metal ions is deeply related to its metabolism pathway web. Putative multidrug efflux transporters, detoxification proteins, extracytoplasmic sigma factors and PAS domain regulators are shown to have higher expression activity in presence of heavy metal. Cytochrome c class protein SO3300 also has an elevated transcription.[4] For example, when reducing U(VI), special cytochromes such as MtrC and OmcA are used to form UO2 nanoparticles and associate it with biopolymers.[5]

Chemical modification

In 2017 researchers used a synthetic molecule called DSFO+ to modify cell membranes in two mutant strains of Shewanella. DSFO+ could completely replace natural current-conducting proteins, boosting the power that the microbe generated. The process was a chemical modification only that did not modify the organism's genome and that was divided among the bacteria's offspring, diluting the effect.[6]

Pellicle formation

extracellular polymeric substances
) help maintain the pellicle matrix. The process of pellicle formation involves significant microbial activities and related substances. For the extracellular polymeric substances, many proteins and other bio-macromolecules are required.

Many metal cations are also required in the process. EDTA control and extensive cation presence/absence tests show that Ca(II), Mn(II), Cu(II) and Zn(II) are all essential in this process, probably functioning as a part of a coenzyme or prosthetic group. Mg(II) has partial effect, while Fe(II) and Fe(III) are inhibitory to some degree. Flagella are considered to contribute to pellicle formation. The biofilm needs bacterial cells to move in a certain manner, while flagella is the organelle which has locomotive function.[10] Mutant strains lacking flagella can still form pellicle, albeit much less rapidly.

Applications

Nanotechnology

Shewanella oneidensis MR-1 can change the oxidation state of metals. These microbial processes allow exploration of novel applications, for example, the biosynthesis of metal nanomaterials.[3] In contrast to chemical and physical methods, microbial processes for synthesizing nanomaterials can be achieved in aqueous phase under gentle and environmentally benign conditions. Many organisms can be utilized to synthesize metal nanomaterials. S. oneidensis is able to reduce a diverse range of metal ions extracellularly and this extracellular production greatly facilitates the extraction of nanomaterials. The extracellular electron transport chains responsible for transferring electrons across cell membranes are relatively well characterized, in particular outer membrane c-type cytochromes MtrC and OmcA.[11] A 2013 study suggested that it is possible to alter particle size and activity of extracellular biogenic nanoparticles via controlled expression of the genes encoding surface proteins. An important example is the synthesis of silver nanoparticle by S. oneidensis, where its antibacterial activity can be influenced by the expression of outer membrane c-type cytochromes. Silver nanoparticles are considered to be a new generation of antimicrobial as they exhibit biocidal activity towards a broad range of bacteria, and are gaining importance with the increasing resistance in antibiotics by pathogenic bacteria.[3] Shewanella has been seen in laboratory settings to bioreduce a substantial amount of palladium and dechlorinate near 70% of polychlorinated biphenyls (PCBs).[12] The production of nanoparticles by S. oneidensis MR-1 are closely associated to the MTR pathway[3] (e.g. silver nanoparticles), or the hydrogenase pathway[13] (e.g. palladium nanoparticles).

Wastewater treatment

Shewanella oneidensis' ability to reduce and absorb heavy metals makes it a candidate for use in wastewater treatment.[6]

DSFO+ could possibly allow the bacteria to electrically communicate with an electrode and generate electricity in a wastewater application.[6]

Genome

Table showing S. oneidensis MR-1 gene annotations.

As a

open reading frames. It has a 161kb plasmid with 173 open reading frames.[14] A re-annotation was made in 2003.[15][16][17]

References

  1. PMID 10319494
    .
  2. PMID 17144297
    .
  3. ^
    S2CID 5903382
    .
  4. PMID 16199584
    .
  5. PMID 16875436
    .
  6. ^ a b c Irving, Michael (February 13, 2017). "Harnessing electricity-generating bacteria to clean up drinking water". newatlas.com. Retrieved 2017-02-13.
  7. PMID 21080927
    .
  8. S2CID 4430171
    .
  9. PMID 18453269
    .
  10. S2CID 26631504
    .
  11. PMID 23765850
    .
  12. PMID 15683392
    .
  13. ISSN 2046-2069
    .
  14. PMID 12368813
    .
  15. PMID 14506846
    .
  16. ^ Shewanella oneidensis MR-1 Genome Page
  17. ^ Whole genome of Shewanella oneidensis

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Shewanella_oneidensis&oldid=1219364519"