How researchers hack bacteria to dye blue jeans

How researchers hack bacteria to dye blue jeans

Most of us can't imagine looking into our closet and not seeing a pair of these, blue jeans. You've got the skinny hipster kind, boot cuts, dad jeans, no judgment. One thing that just about all of our jeans have in common is that blue part, the indigo dye. Unfortunately, the dye we use today is pretty dirty. And because we make a lot, and I mean, seriously a lot of jeans, that one process has an impact, but some people are reinventing the way we make indigo dye. So that in the future, our jeans might just be a little cleaner.

Jeans are iconic, just so that everybody has them in their closet. So, I think that is why they're a great case study.

Every year, it's estimated that billions of pairs of jeans are made, and to give them that iconic blue due , over 70,000 tons of indigo are produced as well, and that indigo is actually key to that classic faded look. - That's what makes jeans so great because like as you wear jeans, this comes off, and you get this like beautiful fading. So, that's why you can only use indigo.

There are actually two kinds of indigo dye that can produce that fade, natural and synthetic. Humans have been using the natural stuff that comes from Indigofera plants for 1,000s of years. But in 1897, German chemists invented synthetic indigo dye for industrial scale production. - These days, almost all jeans are dyed with synthetic indigo dye. Chemically, it's identical to plant-based indigo dye. - So, the end product is the same, but the production process requires a nasty mix of fossil fuels and toxic materials, like formaldehyde, hydrogen cyanide, aniline, and sodium amide.

The problem is what happens when you use synthetic indigo dyes to billions and billions of jeans? Let's dye some fabric. So, the dying process uses a lot of different chemicals. You have the indigo dye itself, but then you also have additives, and that's what allows the indigo to dissolve in water. In our case, we're using soda ash and sodium hydrosulfite, which our dying kit just says, may be harmful if misused. So on an industrial scale, these additives can be harmful to people working in textile factories, especially if the factory isn't up to spec, or they don't have access to PPE. Chemical exposure has been linked to respiratory issues, skin problems, and even some cancers in textile workers. So, I'm not in a textile factory, but it is windy, and better to be safe than sorry. After a few dips, we need to rinse off all of the chemicals with just some clean water here. But not all jeans are created equally, some finished products can contain contaminants like formaldehyde and aniline. So, now we finished dying everything. All we have to do is safely dispose of all this by flushing it straight down the drain. This is just a five-gallon bucket, but as much as 280,000 tons of textile dyes end up as wastewater each year, and not all of it is disposed of properly, especially in places where there aren't good environmental protections, or the industry is unregulated.

- If you go to any factory cities producing these textile products, the rivers are black from the effluence coming out of these factories. That wastewater can foul up aquatic ecosystems, pollute drinking water, and even end up in food grown nearby. -

And I know that a lot of denim laundries, denim brands they're hoping for some sort of innovation where they can move away from synthetic indigo.

But it's not all bad news, there are lots of efforts to improve this process end to end from water reduction to safer finishing techniques, and one company is targeting that blue color that we all love.

So, this is a pretty standard kind of molecular biology lab. This is where we do a lot of our kind of cutting and pasting of DNA to put it into our microbial host. - Huue is a company that makes indigo dye from sugar instead of fossil fuels. They start with an indigo plant and sequence the DNA for indigo compounds. That genetic code gets programmed into microbes, which then produce those exact indigo molecules. - And you can kind of see that some of them are producing a lot of dark blue color, and some of them are producing much less, and so you- - Whichever strains are performing best, get put in a shaker flask to proliferate. Those cultures grow until there's enough to go into a bioreactor. - In each of these reactors, we have either a different strain of our microbe, or the same strain with different kind of media conditions or growth conditions. We can control things like how fast they're stirring and how much oxygen is going into the broth. - The dyes are then analyzed and purified before the testing phase. - So, after the bacteria have kind of grown and produced the indigo dye, it's still kind of this mixture of bacteria, and dye, and the media that it's actually been grown in. We work on purifying out the dye and making sure that the final dye stuff is exactly what a synthetic indigo user would expect.

First, we add the concentrated dye to water. So, now the fabric is going through these rollers. So, here's the first pass of dye. - Huue is still very much in the R&D phase. It's also not the only team trying to solve this problem. DyStar, one of the leading producers of synthetic indigo, has made its die safer for workers and easier to clean. Others have created indigo free of specific contaminants like aniline. Huue is starting with indigo, but they have their sights set much higher. - How do we really create that impact into the fashion industry by really going after the 70 to 80,000 metric tons of indigo that are created every year, and then beyond that the many 1,000s of metric tons of other dyes and colorants that are used in so many other industries. And so, our real focus right now is really putting our solution into the full industrial manufacturing scales so that we can start to deliver material into the fashion industry, and hopefully, be in everyone's next pair of jeans.