( a and only 16 per cent of the C. botul...)Genome of Clostridium botulinum reveals the background to world's deadliest toxin

C. botulinum toxin stops nerves from working — the basis of its use in medicine to control tremors and in cosmetic treatments. For the prey of its opportunistic attacks, death is swift. Perhaps the most important tool it has to act out its stealth attacks is its ability to hibernate when times are hard by forming dormant spores.

More than 110 of its set of almost 3700 genes are used to control spore formation and germination when opportunity arises.

"C. botulinum shows us one extreme of the ways that bacteria can make the most of animal hosts," explained Dr Julian Parkhill of the Wellcome Trust Sanger Institute. "Some organisms use subtle approaches, elegantly choreographing their interaction with us and our defences.

"C. botulinum takes the opposite approach. It lies in wait and, if it gets the opportunity, it hits its host with a microbial sledgehammer. It then eats the remains and lays low until the next host comes along."

The genome sequence is peppered with genes that produce enzymes to digest proteins and other animal material in the soil. Also found, uniquely in this species, is a range of genes that allow it to attack the many insect and other small creatures that live in the soil. The ‘chitinases’ produced by these genes can degrade the casing of insects and small crustaceans.

It is not only animals that can feel the wrath of C. botulinum, explains Dr Sebaihia: "The soil can be a harsh environment and food can be scarce. To see off the competition, C. botulinum comes with its own ‘antibiotic’ — a chemical called boticin that kills competing bacteria."

Genome sequences can tell us a lot about the biology of the organism, but research into clostridia has been hampered by the lack of a good genetic system. Professor Nigel Minton, Professor
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Source:University of Nottingham