Lacto and Yeast

THE RISING — fermentation is tiny life changing food into new food in the warm dark: Lacto makes the tang, Yeast makes the air, and in one bowl of sourdough they do it side by side

Content note: This chapter engages trauma-adjacent themes (sensitive topic). The content has been reviewed for our trauma-informed posture.

A story read by Lacto and Yeast

Loading audio…

Press play to listen along. The line being read lights up as you go.

Show full transcript

Loading transcript…

01 Opening
Lacto and Yeast beat 1 of 5

It was warm in the kitchen after everyone had gone to bed, warm the way a kitchen stays warm long after the oven is off, and in that warmth two of the friendliest little lives on Earth were wide awake and busy.

They worked in the dark. They liked the dark. And — this was the strange, wonderful secret of them both — they worked without any air at all. Most creatures gulp air to live. Not these two. Lacto and Yeast could take a bit of food, tuck into the warm quiet with no air in reach, and transform it, patiently, into something new. People had a word for this slow magic. People called it fermentation. Lacto and Yeast just called it the evening's work.

Tonight there were two bowls waiting on the counter. A crock of plain milk, gone room-warm. And a soft slump of flour and water, sitting under a cloth.

"Which one's mine tonight?" asked Yeast, stretching.

"Both," said Lacto, with a small tangy smile. "Wait and see."

02 Lacto and Yeast
Lacto and Yeast beat 2 of 5

Lacto went to the milk first, because the milk was hers.

She slipped down into it and got quietly to work, and her work was the gentlest transformation you can imagine — she took the plain sweetness in the milk and, slowly, turned it. Not with heat. Not with any rush. Just by living in it, breathing it in her airless little way, and giving back, in exchange, a soft clean sourness. A tang. A bright little zing that had not been there before.

Hour by warm dark hour, the milk changed. It thickened. It cooled its sweetness into something tangy and smooth and good — yogurt, though no one had named it yet tonight. And the marvelous thing was that you could not watch it happen. You could only leave the crock in the warm, and wait, and trust her, and come back to find it done.

"You never hurry," Yeast said, watching the milk quietly thicken.

"You can't hurry it," said Lacto. "That's the whole thing about me. I'm the friend in your food and the friend in your gut, and both jobs are the same job — I take what's plain and make it kinder, one slow hour at a time. Rushing me just leaves you with warm milk." She settled deeper. "Some good things you have to wait for. So you wait. And then, one morning, there it is."

03 Lacto and Yeast
Lacto and Yeast beat 3 of 5

Yeast could not have been more different, and could not have been a better friend for it.

Where Lacto made tang, Yeast made air.

He tucked into a warm bit of dough, found the sweetness hidden in the flour, and fermented it his own way — and the leftover of his work, the gift he gave off without even trying, was gas. Tiny puffs of it. Bubbles. Hundreds of them, then thousands, each one a little breath blown softly into the dough from the inside.

And the dough, full of all his tiny breaths, began to rise.

It swelled. It lifted. It went from a flat heavy slump to a soft billowing pillow, light and full of holes, every hole a place where Yeast had once breathed out. "That's me," he said, proud and a little shy about it. "I make air inside bread. All the softness, all the spring, every little hole you love in a good slice — that was me, breathing in the dark where nobody could see." He gave the dough one more gentle lift. "It's a good job, making room. Making something heavy turn light."

04 Lacto and Yeast
Lacto and Yeast beat 4 of 5

And then Lacto climbed up out of the milk, and crossed the warm counter, and slipped into the very same dough beside him.

Because the second bowl — the soft slump under the cloth — was not just Yeast's. It was both of theirs. It was sourdough, and sourdough is the oldest bread there is, and its whole quiet miracle is that it needs the two of them at once.

So they worked it together, side by side, doing their two completely different jobs on one shared thing. Yeast breathed his bubbles in and the dough rose. Lacto laid her soft tang through it and the bread turned deep and sour-sweet and good. Neither did the other's job. Neither could have. The rise was all Yeast; the flavor was all Lacto; and the loaf — the real, whole, wonderful loaf — needed every bit of both.

"Funny," murmured Yeast, as the dough grew warm and alive between them. "On my own I just make a plain puffed loaf. On her own she just makes something sour. But together—"

"Together we make bread worth waiting for," said Lacto.

05 Closing
Lacto and Yeast beat 5 of 5

By morning it was done.

The crock held cool tangy yogurt where plain milk had been. The bowl held a high soft risen dough, freckled all through with the little breathing-holes and the deep sour scent, ready for the oven. Two plain foods had gone into the warm dark the night before. Two new foods had quietly come out.

Nobody had watched it happen. That was always how it went. The two of them did their slow transforming in the dark, without any air, without any hurry, without anyone standing over them — and then someone woke up, and lifted the cloth, and there it was: risen, changed, ready.

Lacto and Yeast settled down to rest as the first light came in the window. They were tired in the good way, the way you are after making something that took all night and all your patience.

"Not bad," said Yeast, "for two little friends who work in the dark."

"Not bad at all," said Lacto.

And there is a warm and steadying feeling in that, if you have ever felt it — the feeling of a slow, quiet becoming; of changing something gently instead of grabbing at it; of being trusted to sit in the warm and the dark and do your patient part, so that in the morning someone lifts the cloth and finds, waiting there, the good thing you made while no one was watching.

The MicrobeLab ensemble

Lacto and Yeast is part of MicrobeLab's distributed-narrative cast. Each character embodies a different curricular primitive; together they teach the full subject.

Kids also liked