''Paraclostridium bifermentans'', formerly known as ''Clostridium bifermentans'' and abbreviated CLOBI, is an

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

motile Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

gram-positive bacterium In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

Toxins and mosquito larvae

A certain

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

, ''Clostridium bifermentans'' subsp. Malaysia, was the first anaerobic bacterium known to kill mosquito larvae. The subspecies was part of a collection at the Institute for Medical Research, Malaysia. A biochemical analysis found that the mosquitocidal

cry toxin Delta endotoxins (δ-endotoxins) are pore-forming toxins produced by '' Bacillus thuringiensis'' species of bacteria. They are useful for their insecticidal action and are the primary toxin produced by Bt maize/corn. During spore formation ...

is coded by four genes in an

operon In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter. The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splic ...

: cry16Aa, cry17Aa, cbm17.1, and cbm17.2. When the four genes were individually expressed, none of the four proteins encoded exhibited mosquitocidal activity. This suggests that the toxicity requires four proteins cooperating as a complex to take effect. A single promoter was found upstream of the four genes, indicating that the four were likely to be expressed simultaneously. The half-life of toxicity was about one day and the toxin was unstable in high temperature. Although ''C. bifermentans'' subsp. Malaysia is shown to be more lethal to ''

Anopheles ''Anopheles'' () is a genus of mosquito first described and named by J. W. Meigen in 1818. About 460 species are recognised; while over 100 can transmit human malaria, only 30–40 commonly transmit parasites of the genus ''Plasmodium'', which c ...

'' mosquito larvae, the toxin produced by Cry operon has no mosquitocidal effect on mature ''Anopheles'' individuals. Thus, the genes accountable for the toxicity towards ''Anopheles'' are different than those controlled by the cry operon; rather, the toxins selectively target ''

Aedes ''Aedes'' is a genus of mosquitoes originally found in tropical and subtropical zones, but now found on all continents except perhaps Antarctica. Some species have been spread by human activity: ''Aedes albopictus'', a particularly invasive spe ...

'' mosquito larvae, in which they cause high mortality.

References

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External links

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''Clostridium bifermentans''
at Bac''Dive'' {{Taxonbar, from=Q3681019 Gram-positive bacteria Bacteria described in 1918 Clostridiaceae