Culture medium (pl. media)
Culture medium
Japanese: 培地（培養培地）
A nutrient-containing environment for growing microorganisms. Includes liquid media and solid media (agar plates), with carbon sources, nitrogen sources, and minerals formulated for specific purposes.
A culture medium is an environment serving as both food and housing for microorganisms. Carbon sources, nitrogen sources, minerals, and vitamins needed by the microbes are dissolved in water, solidified with agar if needed.
Liquid media suit large-scale cultivation; solid media (agar plates) are used for colony observation and pure culture. Each colony on a plate traces back to a single cell.
Media design is tailored to the target organism's properties. Selective media are formulated so only specific organisms grow. Differential media visualize metabolic differences through color changes.
In fermentation practice, growing koji mold on steamed rice is also, in a broad sense, the act of designing a medium. Without good media, good fermentation cannot begin.