A Word About

Inoculum Preparation

Inoculum preparation is the process of growing the cells from the "bullet" to the point where they can be added to a bioreactor. The process is sometimes called "cell expansion"

The "bullet thaw" is the operation in which a vial of the genetically engineered cells stored at -140°C is thawed and suspended in growth medium. Following this, the cells are initially grown (to attain a greater number of cells, not to generate a significant amount of product) in an incubator for temperature control. Within the incubator, the cells can be contained in one of several types of device:

A typical inoculum operation passes the cells through several stages of the above devices. At each stage, the volume of media is expanded (decreasing the concentration of cells). In most processes, the last stages of the inoculum preparation take place in small bioreactors, described under Cell Culture.

inoculum train
Schematic of a typical inoculum train (from GE Life Sciences). The number of stages varies from product to another. For example, there may be only one small bioreactor before the production bioreactor.


Page updated 7/7/17


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