Yeast is fascinating! It seems like some types can eat just about anything, while others are super picky eaters. Scientists from big universities got together to figure out why that is. They studied over a thousand different kinds of yeast, looking at their genes and what they like to munch on.
Turns out, the reason for all these different diets isn't about where the yeast lives, it's in their genes! The amazing part is, some yeasts can eat tons of stuff and be good at it all – there's no downside.
This massive study, by the way, was all about understanding yeast way better. It even helps scientists figure out how to make better yeasts for cool stuff like making fuel from plants instead of oil!
Many branches, varied appetites
Remember that big family of yeasts related to the kind we use to make bread? Well, way back in 2015, Hittinger's team got super curious about them. They analyzed the genomes and diets of nearly every species in the group.
Why this specific yeast family? It had tons of different members with super varied eating habits!
"It's like a huge family tree with relatives close and far," says Hittinger. "This lets us see how the same changes happened across different branches – did they pick up or lose certain traits a bunch of times?"
The tricky part was figuring out how all these yeasts were related.
After lots of data-crunching, they used fancy machine learning tools to link specific genes to traits. These traits tell us what a yeast can eat, or the kind of environment it likes – basically, how picky or flexible it is with its lifestyle.
Turns out, yeasts are like us! Some are specialists (think of those koalas only eating eucalyptus), while others are generalists (like raccoons who'll eat almost anything).
This whole idea of specialists vs. generalists has been puzzling scientists since Darwin's time!
"Think back to Darwin's early days," says Hittinger, "people were starting to realize how the environment shapes which species survive. That's the whole idea behind natural selection!"
Think of yeast like people at a buffet! Some yeasts are picky eaters, while others will try anything. Hittinger's team wanted to figure out how all these different yeast "families" are related and why their tastes are so different.
They studied a ton of yeasts, checking out their genes and what they preferred to munch on. Just like us, some yeasts have evolved to be specialists – they only like certain foods. Others are like adventurous eaters, happy with a wide variety of snacks!
This whole question of why some yeasts are picky and some try anything has been a puzzle for scientists for a super long time – even back when Darwin was around!
Think of a giant yeast family tree – that's what scientists built after studying over a thousand different yeasts (plus some of their fungus cousins). They figured out how these species are related using a ton of gene data!
The branches of the tree are color-coded to show where each yeast was originally found. It's like a map of who lived where! On top of that, they ranked each yeast on how versatile its diet is – basically how wide a range of things it can "eat" for energy.
The cool takeaway? This yeast family tree is super diverse! Different diet preferences and living environments show up all over the place – there's no single group that has it all the same.
Scientists have a couple of big ideas about why some species are picky, and others will try anything.
Idea #1: Generalists are like the "okay at everything, great at nothing" crowd. They can handle lots of different situations or foods, but might not be the absolute best in any one area.
Idea #2: Think of it as a mix of nature and nurture for species like yeast. Sometimes, they pick up genes that help them digest more stuff, widening their food options. Other times, they might randomly lose genes over generations, making them specialists.
The place they live matters too! If a yeast's home only has one or two kinds of food, specialists win. But if the environment keeps changing, generalists who can adapt might have the upper hand.
Hittinger's team looked at how yeasts use food, and guess what? Generalists rocked!
"They're better at digesting all kinds of stuff," Hittinger says. "Plus, they can use more types of nitrogen for fuel than specialists can. That totally surprised me!"
Where a yeast lives didn't seem to make much of a difference either.
"You'd think specialists would be more common in controlled environments, but nope," says co-author Dana Opulente. "We find both specialists and generalists in the wild – in the soil, on flowers...all over!"
Hittinger does point out that this study has limits. Maybe other yeast species have those tradeoffs they were looking for. Plus, the lab experiments might be pretty different from real life in the dirt or inside a bug!
Opulente is investigating those natural yeast habitats, which might show that the environment matters more than they thought.
"The more we learn, the more questions pop up!" says Opulente.
But there's one big mystery the study didn't solve: If generalists have it so good, why isn't every yeast a generalist?
Maybe it's just random gene changes over time. If a change isn't life-or-death for the yeast, it can spread and create a more specialized population.
"We're still not sure on that one," says Hittinger.
Where to find the study: This cool article about how yeasts can be specialists or generalists appeared on April 25, 2024, on a website called phys.org. Here's the link if you want to read it:
https://phys.org/news/2024-04-yeast-species-generalists-specialists.html
Important Note: Websites often have copyright rules which means you can't just copy and paste stuff without permission. This is mostly for when you're doing things like school research or writing your own articles!
Want to dig deeper into this yeast study? You can! Check out the full report by Dana A. Opulente and the team. It was published in the journal Science (2024). Here's the direct link: www.science.org/doi/10.1126/science.adj4503
Tags:
Yeast • Biology • Genetics • Evolution • Research • Genomics