Some bacteria have evolved to live in one of the most hostile environments imaginable: inside the venom glands of snakes, spiders and scorpions. As well as highlighting how adaptable microorganisms are, the finding also suggests that antibiotics should be used more to help treat snakebites.
People who have been bitten by snakes , but this was thought to be of having an open wound that has been inside the snake鈥檚 mouth. The venom itself is highly toxic so was assumed to be sterile.
However, of Venomtech Limited in Sandwich, UK and of Northumbria University, UK suspected that there might be microbes living in the venom. For one thing, the duct of the venom gland is always open, says Trim. What鈥檚 more, the venom only flows occasionally, so there are long periods of inactivity during which bacteria could 鈥渃limb鈥� up into the venom gland.
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The pair and their colleagues sampled the venoms of five snake species, two spiders and two scorpions. 鈥淲e found viable bacteria and whole genomes from many organisms across all species we investigated,鈥� says Trim.
Hostile environment
It鈥檚 a striking feat of adaptation. The venom gland is 鈥減robably the most hostile biological environment鈥�, says Trim. He says stomach acid is probably the only part of an animal鈥檚 body that is more dangerous for bacteria.
They took a closer look at the snake venom 鈥� which they could obtain in larger quantities 鈥� and found that each species had its own mix of bacteria. For instance, the microbiome of the venom of African puff adders (Bitis arietans) was quite different to that of black-necked spitting cobras (Naja nigricollis).
The team found evidence that the bacteria had adapted to life in venom. They had extra genes for transporter proteins that carry molecules out of the bacterial cells. The bacteria were also enriched in genes for proteins involved in maintaining their outer membranes, which might also help them survive by keeping out the venom.
Trim says doctors treating snakebites should assume that their patients are at risk of infection. 鈥淩ather than waiting to see if it gets infected and then treating the infection, there鈥檚 a strong [argument] to say you should be giving prophylactic antibiotics,鈥� he says.
Reference: bioRxiv, doi:
