Blasting Yeast with UV Light

[teekert]

Fun story. I worked at a large food tech company. For products like Yoghurt you’d like Bactria that make the yogurt very quickly at high temp. But grow as slowly as possible at low temp (stays fresh longer).

They’d mutate the s out of these Bacteria, in smart calculated ways. A basepair here, a gene there. When they hit a jack pot. They’d document the mutations, throw the engineered strain out and start blasting them with UV. Afterwards you just scan for the same mutations and voila, now it’s classical strain enhancement!

Same was done for yeast for all kinds of food applications.

There is something to be said for it because you never need antibiotic resistance for selection that way. But you also don’t really know what you are doing and you could edit the resistance genes out. Anyway, this was >20 years ago. Maybe they do it differently now.

[sheepscreek]

Wow. My mind is truly blown.

For anyone else wondering, I learned that in order to naturally create bacteria that aren’t going to be labelled GMO, you can blast regular bacteria with UV, then look for the ones with the same mutations as the engineered ones (with desirable traits), and now you can legally use the “natural” bacteria in Non-GMO labelled products.

Putting my personal views (from a consumption pov) on this topic aside, that is some clever “engineering”.

[tdeck]

This reminds me of atomic gardening, where you just blast plants with gamma rays and see if you get something useful

https://en.wikipedia.org/wiki/Atomic_gardening

They still do it in Japan, with a distinctive circular field that has a radioactive isotope tower in the center

https://www.naro.affrc.go.jp/archive/nias/eng/org/GR/IRB/

[endgame]

Parallel construction, but to work around GMO labelling as opposed to LEOs revealing their sources.

[vecter]

> When they hit a jack pot. They’d document the mutations, throw the engineered strain out and start blasting them with UV. Afterwards you just scan for the same mutations and voila, now it’s classical strain enhancement!

Instead of starting with a fresh gene pool and blasting it with UV and praying that they get the same jackpot mutations, why didn't they start with an entire population with that desirable jackpot mutation and those blast cells with UV and then select for the ones that survived?

[roldie]

Thanks for sharing, this is fascinating

[secondcoming]

How can you scan millions of things looking for one or two that have a mutation?

[anfractuosity]

Since as far as I understand the UV light also acts as a mutagen, wonder if you could potentially create some interesting new yeast strains for brewing.

It might also be interesting to use a dye to highlight dead cells.

[ecesena]

Part 2: https://chillphysicsenjoyer.substack.com/p/my-uv-experiment-...

[seanwilson]

For sourdough and breadmaking, I always find it funny how recipes and tips make out like yeast is almost delicate and hard to keep happy when we know yeast is super tough. It can survive drying, cold/freezing, high pressure, having no food for a long time, up to 50C heat, and more.

It's also easy and cheap to run experiments too like mixing salt directly with the yeast and seeing it doesn't make a noticeable difference to breadmaking, yet the myths persist.

[mtrovo]

The problem in general is consistency. Bread is very forgiving on flavour profiles so what you're saying works fine within a good threshold. For breweries it's usually not worth it as there are lots of nuances on the mutations of the harvested yeast and their effects into the flavour profile of the final product. There are some exceptions like natural fermented beers or anything related to kveik yeast, but in general people don't reuse yeast past 1-2 brews.

[TomMasz]

A local apple farm and cider mill uses UV for pasteurization of their cider instead of heat. I use it to make hard cider, and it's as good as unpasteurized cider (no longer legal to sell in NY) was, and I don't have to use sulfites to kill off wild yeast.