Team:Copenhagen/Project/Cyanobacteria
Cyanobacteria
Cyanobacteria, also known as blue-green algae, are bacteria that are special in that they use photosynthesis and thereby act like plants to convert CO2 from the atmosphere into the sugars they need. Therefore, when working with cyanobacteria one does not need to feed them any sugar. Thus, they are very cheap to culture and as an extra benefit they reduce the level of CO2 in the atmosphere.
Cyanobacteria can live pretty much everywhere! In water habitats, both in ocean and fresh water, but also on soil and rocks. They live in the most extreme places, in hot springs and hypersaline bays.
In our project we work with cyanobacteria of the genus Synechococcus that live specifically in salt water and are abundant in the world oceans. These bacteria have a light harvesting apparatus especially adapted to obtain light in the ocean. Besides fixing CO2 they also acquire nitrogen from the atmosphere.
Like several plants and animals, the lives of cyanobacteria have a circadian rhythm, which is controlled by a circadian clock. It is an internal clock that controls the activity of different genes during approximately 24 hours to diversify “night” behavior from “day” behavior of the bacteria.
Bioluminescence
Bioluminescence is light produced by a chemical reaction and subsequently emitted from the living organism in which the reaction takes place.
One of the more known organisms to produce this kind of light are fireflies, but many other, such as bacteria, are able to emit light as well. Bioluminescence is used in nature for many different purposes. Some use it to scare of enemies, others as camouflage or even to attract mates.
Luciferase is the major light-producing enzyme. It catalyzes the oxidation of the compound luciferin into a unstable intermediate which by emitting light will decay into a favorable ground state.
As in nature, bioluminescence has a broad range of applications in biotechnology as well. A common use is different imaging methods and expression analyses.
A. fischeri are gram negative bacteria that can live in symbiosis with for example squid and thereby make them glow. The bacteria contain an operon which is a collection of genes that are all controlled by the same promoter and therefore expressed simultaneously. The Lux operon in A. fischeri contains the genes Lux A, Lux B, Lux C, Lux D and Lux E whose joint function is to produce the enzyme luciferase and regenerate the components necessary for the enzyme to work. The gene expression is controlled by an inducible-promotor meaning that different stimulants such as certain wavelength of light, a high colony concentration or the presence of a certain protein, can initiate the light production.
In our project the lux operon will be placed in the cyanobacteria PCC 7002 and a night induced promotor lrtA
<a href="http://partsregistry.org/Part:BBa_K390008" style="text-decoration:none; color:blue;"> BBa_K390008</a>
will control the transcription and thereby the production of light. |
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