In a vain attempt to inject some science into this blog, I thought I might consider some popular "facts" about bacteria which appear in some science textbooks and are thus perpetuated as urban myths within the scientific community. The most popular one, which I'll start with is:
Bacteria have a singular, circular chromosome
Many bacteria, including the "model" bacterium Escherichia coli, that do have only one chromosome. However, there are numerically more bacteria in the world that have not one, or two, but many chromosomes. For example, Rhodobacter sphaeroides has two circular chromosomes, and Paracoccus pantotrophus has at least 4, one of which is linear. The possession of a linear chromosome isn't unusual. One of the most important organisms in biotechnology, Streptomyces coelicolor, has a single linear chromosome too.
Showing posts with label Bacteriology. Show all posts
Showing posts with label Bacteriology. Show all posts
Monday, 1 October 2007
Friday, 29 June 2007
New cork, old bottle
Craig Ventner is back in the news again, after the on-line publication of his experiments involving "Changing One Species to Another". I haven't read the full article (and look forward to doing so) but the experiment seems straight forward enough: isolate genomic DNA from Mycoplasma mycoides (which has a very small genome but possesses a tet resistance gene); transform Mycoplasma capricolum with this DNA and select for tet resistance. The abstract suggests rigorous testing to ensure that all the genetic properties of M mycoides are present in the new species, and none of M capricolum. A very neat experiment, but does this really show one species being changed to another?
In the rather fluid species definition of Bacteria, the genome is the most important thing. It alone defines the characteristics of the bacterium. Isn't this procedure a bit like (by very very dodgy analogy) implanting a sheep foetus into a goat and calling the whole thing a new hybrid?
Nothwithstanding the semantics of the use of the word species in the title, it does signal a small jump forward in the quest to design bacteria with particular properties.
There are a few more details here though this is a dynamic link that may not repsond for very long.
In the rather fluid species definition of Bacteria, the genome is the most important thing. It alone defines the characteristics of the bacterium. Isn't this procedure a bit like (by very very dodgy analogy) implanting a sheep foetus into a goat and calling the whole thing a new hybrid?
Nothwithstanding the semantics of the use of the word species in the title, it does signal a small jump forward in the quest to design bacteria with particular properties.
There are a few more details here though this is a dynamic link that may not repsond for very long.
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