Preculture

Preculture, or pre-culture, is the preliminary culture grown before a main production culture. Its purpose is to prepare a healthy inoculum by increasing cell density and ensuring the cells are in an appropriate physiological state for rapid, predictable growth in the production medium. Precultures are commonly used in microbiology, biotechnology, and related fields to improve consistency and performance of subsequent fermentation or cell culture steps.

In typical practice, a stock culture is revived from cryopreserved or lyophilized material and is first inoculated into a small seed culture. The seed culture is grown to a desired growth phase, often mid-log, and may undergo an adaptation or acclimation step to better match the conditions of the production medium, such as its carbon source, salinity, or pH. The resulting culture then inoculates the main production medium. This staged approach helps reduce lag time, stabilize performance, and improve overall process reliability.

Preculture concepts also appear in plant tissue culture and mammalian or other cell cultures, where initial handling and conditioning of explants or cells aims to maximize viability and maintain desired characteristics before large-scale culture or application.

Key considerations for preculture include matching the preculture and production media as closely as possible, controlling temperature, pH, and oxygen availability, and minimizing contamination and selection biases. Poorly chosen preculture conditions can lead to inconsistent growth, unwanted physiological states, or poor performance in the main culture. In bioprocessing, precultures are often viewed as an important step in achieving reproducible and efficient production.