Blasting Yeast with UV Light

Blasting Yeast with UV Light(chillphysicsenjoyer.substack.com)

82 points by Gormisdomai 186 days ago | 26 comments

teekert 186 days ago |

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 186 days ago | |

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”.

crdrost 186 days ago | | |

There are a bunch of tricks like this. So for instance to make antibiotic-free chicken without a commitment to being antibiotic-free and organic, raise a bunch of chickens, take any who gets sick enough to need antibiotics and put them into a separate field with their antibiotics, sell the ones that happen to not get sick as antibiotic-free, sell the other ones as usual.

Or, if you're making orange juice, make the ingredients label say oranges. But you can split it up, take the peels, put them into a hydraulic press, extract out oils that have the concentrated aroma and flavor of oranges, homogenize some of that into the juice. Or you can centrifuge the juice, or you can pass it through osmotic filters to remove some of the water and concentrate the flavor. No rule saying you can't treat some of the juice similar to sugar beet juice and try to isolate its sugars. At the end, you reassemble a perfect consistent mixture. The label doesn't have to tell you about any of this, it just has to tell you that the ingredients were oranges.

(The recipe for the best lemonade you'll ever make is like this, it's just lemons and water and sugar, but you zest the lemons into the simple syrup you're making with the sugar water, then strain it with cheesecloth or a coffee filter, before adding to the juice and water and pulp.)

Imported oils, you can basically do anything that some middleman country allows you to do with the oil (in particular mix with cheaper oils) and then say "oh this is imported olive oil, olive oil according to someone else's standards”...

Qem 186 days ago | | |

> that is some clever “engineering”.

Looks like when law enforcement does the infamous parallel comstruction trick, gathering evidence through illegal means and later pretending to have just discovered what they secretely already know, but through legal means this time. See https://en.wikipedia.org/wiki/Parallel_construction

DenisM 186 days ago | | |

if you haven’t done that yet look into “the green revolution”. The practice of blasting things with radiation is rather old. Some of the Most used crops are the product of that process, and yet are perfectly “organic”.

tdeck 186 days ago | |

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 186 days ago | |

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

vecter 186 days ago | |

> 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?

addaon 186 days ago | | |

GMO labeling rules.

roldie 186 days ago | |

Thanks for sharing, this is fascinating

secondcoming 186 days ago | |

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

londons_explore 186 days ago | | |

If you accidentally use the same pipette for the GMO and then non-GMO one, your chances are hugely increased...

teekert 186 days ago | | |

Back in the day there were pipetting robots and 384 well plates. Probably some smart grouping techniques to hone in on a mutation in a binary search like fashion.

But nowadays we have things like single cell sequencing, which allows you to label thousands of cells with unique DNA barcodes (not the cell itself but the sequencing library you construct to go into the sequencer), and sequence them all in a massive parallel fashion.

Basically all of molecular (and other types) biology is now "high throughput", consequently data science has become very important for biologists.

XorNot 186 days ago | | |

You already had to have a selection process to establish the desired trait and determine whether it was successfully hybridized into the target.

Once you know what it is, you run the same thing on the unmodified population.

rcxdude 186 days ago | | |

PCR allows you to detect a particular DNA sequence at extremely low concentrations (essentially, by duplicating any DNA that matches it many times).

anfractuosity 186 days ago |

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 186 days ago |

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

seanwilson 186 days ago |

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 185 days ago | |

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 185 days ago |

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.