My Microbial Companion: Nukazuke

Assignment:

Start a microbial culture that you will keep as a companion for the rest of the semester.

Idea:

Nukazuke are Japanese rice-bran ferments. They’re made by first preparing a bed of rice bran, salt, water and additional ingredients like mustard powder, kombu, dried red chili flakes and garlic. Other add-ons can be used instead of these. After mixing together the ingredients, bury a vegetable, chopped if necessary but with skin-on, in the rice bran bed. The salt in the rice bran bed functions just like salt in a lacto-ferment; it promotes healthy lactobacilus growth and inhibits other pathogenic bacteria that can’t survive in higher-salt concentrations. The rice bran supplies sugar for the naturally occurring bacteria in the air, and the buried vegetable (especially its skin) often carries a lactobacilus biome that will help begin culturing the rice bran bed.

Each day until mature, swap out the vegetable in the bed. This helps promote a more diverse microbiome in the rice bran bed. I’ve been tasting the pickles each of the last two days; they are noticeably transformed from their normal state, slightly sweeter and saltier, but still very young for a nukazuke. I expect that within a week I will have a mature bed.

Once the bed is mature, I’ll be burying vegetables or ~12 hours or more to get the fermented final product. I’ll try different vegetables, and eventually I may take some of the mature culture to

I followed this recipe, and also learned a lot from The Art of Fermentation by Sandor Katz.

Scaling Intuition

Assignment: Capture relationships between objects at different scales.

The motivation behind this assignment was, in part, to build an intuition for size, scale and relationships between objects and space. We will need to hold onto this intuition when shrinking down to micro-scale. Something I found interesting while doing this assignment, which I suspect will return when we study bioinformatics techniques: as the scale between objects increased, I began approximating the density of objects in a given area rather than precisely measure the relationship.

Initially, at 1:10 scale, it was easy to measure an exact relationship between my chosen objects, books, to one another. As I moved to a sewer grate grid, I could count the rows and columns, calculate the number of rectangles in the grid, then find the relationship between one rectangle and the whole grid.

But once I got to the tiles in the ITP foyer with irregularly-shaped specks as their building blocks, I began approximating the number of specks in a given area (a rectangle), then approximating the number of rectangles in a tile, then counting the number of tiles in the foyer before arriving at a calculation. When scaling bacterial activity from a sample to a real location, I imagine we will need to do something similar.

In the realm of counting

1:10 // Height of 1 book : Height of stack of books

1:600 // 1 rectangle in this Brooklyn sidewalk sewer grate : ~600 rectangles in the entire grate

In the realm of approximation

1: 1000 // 1 oval in on the back of a chair in an ITP conference room: 1000+ ovals in the entire mesh

When I refer to “specks” in the next two examples, I mean one of the light-colored irregular shapes in the tiles below.

1:100000 // 1 speck : 9 tiles

I counted ~100 specks in a rectangular area, then approximated the number of rectangles in 1 tile. I estimated that there were ~16,000 specks per tile. So roughly 1 speck in 1 tile compared against 6.25 floor tiles would give a 1:100000 relationship.

1:1000000 // 1 speck in 1 tile: ~63 tiles (there are 320 tiles, so 1 speck: whole floor is about a 1:6000000 relationship!)