[♪ INTRO].

Squid is pretty delicious, unless you overcook it, and then it tastes like you're eating a rubber band. The point is, the high demand for this critter around the globe keeps commercial squid fisheries pretty busy.

And one of the downsides is that these operations create a lot of waste. Every year, they throw out thousands of metric tonnes of squid skin, which is pretty unfortunate, and not just for the environment:. As it turns out, some of that skin contains a compound that could help us fight some of the most common disease-causing microbes out there.

And weirdly enough, this compound is found in a pigment squid use to change colors. Squid can change the color and pattern of their skin at a moment's notice, either to hide or to communicate with each other. And they do it using thousands of organs in their skin called chromatophores.

Chromatophores are made of a sac filled with pigment, surrounded by a ring of muscle. And they can expand and contract at the blink of an eye, spreading or withdrawing pigment as they go. And the antimicrobial pigment scientists are interested in comes from a few species, including the Humboldt squid, also known as the jumbo squid.

It's called xanthommatin, and for a while, we've known it acts as an antioxidant. In other words, it helps protect a squid's cells from reactive forms of oxygen that can damage tissues. But researchers also noticed that it can prolong the shelf life of a couple of commercially-processed fish species.

So they began to suspect it might be an antimicrobial, too. They tested this hypothesis and published the results in a 2019 paper. In the experiment, they pulled the pigment from jumbo squid skin, and mixed it with a growth medium, plus several microbes that cause illness in humans.

Specifically, they tested the pigment on multiple species of bacteria, including ones that cause foodborne illnesses like salmonella and listeria. And they also tested it on a few species of fungi that produce toxins, plus several candida species. Those are yeasts that cause thrush and yeast infections.

And the results were pretty impressive. The pigment was over 90% effective at stopping salmonella bacteria from growing. And it was over 50% effective at limiting the growth of listeria, staphylococcus, a bacterium that causes pneumonia and other infections, and a species of Candida called Candida albicans.

And to think, fisheries have been throwing this stuff out for years! This creates environmental problems along coastlines, and based on this study, we might also be wasting a helpful compound. At this point, we'll need to do more testing to see how effective this pigment could be in battling human or foodborne illnesses, since our bodies are way more complex than cells in a dish.

But it's possible that this could help us stay healthy. So reducing waste from commercial fishing and keeping us safe? That sounds like a win-win to me.

Thank you for watching this episode of SciShow! If there's a mind-blowing science fact that you think we really need to know, go ahead and leave it in the comments below. And if you want to keep up with all of our Fast Facts, just hit that subscribe button below the video. [♪ OUTRO].