If the first step is positive, a second test, a PCR assay targeting the toxin genes, is performed.

For example, a laser beam or a controllable gene promoter for a toxin gene can be used to destroy a selected amount of cells.

The advantage of this gene is that insecticidal toxin genes or other various herbicides can be engineered in the bacterial DNA.

Its cereus cousin has a similar main chromosome, but its plasmids lack the toxin genes that make anthrax so deadly.

Thus, for example in Escherichia coli, identifying strains carrying toxin genes is more important than having a population genetics-based evaluation of prevalent strains.

Unusually, the toxin gene is encoded by a bacteriophage (a virus that infects bacteria).

In 1951, Freeman found that the toxin gene was not encoded on the bacterial chromosome, but by a lysogenic phage infecting all toxigenic strains.

However, these integrations sites are degraded indicating that the C. botulinum acquired the toxin genes quite far into the evolutionary past.

It is proposed that Photorhabdus species acquired the toxin genes by horizontal gene transfer during evolution.

The study has uncovered toxin genes and other genes that may be responsible for the virulence of the fungus.