Koji spores, or koji tane, are the inoculum used to begin a fresh batch of koji. They are sold either as a concentrated powder or on dried grains of rice or barley; both forms can inoculate a different cooked-grain substrate.1
For every 1 g of powdered spores, mix with 9 g of toasted flour or starch. The carrier makes the tiny quantity easier to distribute evenly with a shaker or sieve; a little inoculum goes a long way.1