These filter feeders remove nutrients and bacteria from the water concentrating the levels of bacteria and hence TTX within their bodies. The bacteria, that can produce TTX, start life in the silt and sediment which is then eaten by molluscs.

As we go higher up the food chain the amount of TTX accumulates and concentrates in complex animals until it reaches levels which are lethal to those who eat these animals, including humans. Like many toxins and chemicals in higher animal species, TTX actually starts in small quantities in organisms at the very bottom of the food chain. I did tell you this is a Microbiology blog, honest… This where the microbiology comes in… TTX is actually produced by bacteria! However research in 1968 also discovered TTX in California in a species of newt previously it was thought that only the pufferfish “produced” TTX, but when they looked further they actually found TTX “contained” in silt and sediment as well as lots of different animals!Įven though these are all aquatic animals it is very unlikely that the ability to “produce' such a specific toxin has evolved in so many different animals in different locations around the World, so there must be another explanation for the presence of TTX. The first published association between pufferfish and TTX was “rediscovered” in 1894 I say rediscovered because the association between pufferfish and its toxic effects was actually described in ancient Egyptian texts as far back as 2500BC. What the heck does TTX poisoning have to do with microbiology? Whoa! Hold on! Isn’t this supposed to be a microbiology blog, not a blog about fish or fancy foods or holidays?! Okay, stick with it, I’ll explain… Anyone for the plato de mariscos del día? OK so maybe the recent ban on going on holiday due to Covid-19 isn’t such a bad thing after all… okay I’m really reaching here and trying to look on the bright side… my holiday is being canned… the South African government have placed UK residents are on a banned list for entry! TTX poisoning has also occurred closer to home with a case in Malaga, Spain, in 2007 due to eating shellfish caught in Portuguese waters and in Greece in 2012 from TTX containing molluscs. Why anyone would want to eat something that could kill them I do not know….! To mitigate the risk only specially trained and licensed chefs are allowed to prepare fugu paying careful attention to avoiding the puffer fish’s liver and ovaries where the highest levels of TTX are. It blocks sodium channels in muscles and nerves causing paralysis and eventually death.

In fact TTX is one of the most potent neurotoxins we know of, being 1200x more toxic than cyanide. However, eating badly prepared fugu can be the last thing you ever do! Pufferfish meat can be contaminated with a neurotoxin called Tetrodotoxin (TTX) and even if you cook the fish (heating doesn’t destroy the toxin) eating a contaminated fish is really bad for you. Unfortunately for Bloat, eating pufferfish, known as fugu in Japan, is a delicacy.

Fugu deaths 2017