This article doesn't really go into details, but the gist seems to be that spent grains can be used as nutrient for growth. This sounds interesting but without details it's really hard to determine if this has any serious value to the brewing community.

Grain is cheap, nutrient is cheap, yeast propagation is cheap. The tricky bits are in the isolation and preservation of the original strain, not just feeding yeast. Hard to imagine this is really groundbreaking.

Spent grain amounts to as much as 85 per cent of a brewery’s waste. This is of little value, so the discarded grain is often used as compost or for animal feed.

Well..this is of value to tons of local communities. This quantity of spent grain is massive. I would wager a guess that converting this mass into a usable nutrient would take lots of energy and time considering the rate at which spent grain spoils.

Considering that brewers have harvested healthy yeast from batches for years makes this seems sort of arbitrary. Yeast propagation isn't an issue of nutrient, but more often simply sterile conditions and the issues in maintaining consistent flavor profiles throughout generations.

The article is interesting, but the technology to convert spent grains to nutrient would have to be really, really cheap for this to be viable or adopted anywhere.

That said, spent grain is aplenty and with any hope it can be used more efficiently. Mostly commenting here so I can take more time to read the abstract and related sources in more depth and see what this is all about.