发酵培养基从广义上而言，是指可供微生物细胞生长繁殖所需的一组营养物质与原料。同时其也为微生物培养提供其他所必须的条件。发酵培养基的基本作用在于满足菌体的生长，促进产物的形成。

• 培养基能够满足产物最经济的合成。
• 发酵后所形成的副产物尽可能的少。
• 培养基的原料应因地制宜，价格低廉；且性能稳定，资源丰富，便于采购运输，适合大规模储藏，能保证生产上的供应。
• 所选用的培养基应能满足总体工艺的要求，如不应该影响通气、提取、纯化及废物处理等。

A growth medium or culture medium is a solid or gas designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens. There are different types of media for growing different types of cells.

There are two major types of growth media: those used for cell culture, which use specific cell types derived from plants or animals, and microbiological culture, which are used for growing microorganisms, such as bacteria or yeast. The most common growth media for microorganisms are nutrient broths and agar plates; specialized media are sometimes required for microorganism and cell culture growth. Some organisms, termed fastidious organisms, require specialized environments due to complex nutritional requirements. Viruses, for example, are obligate intracellular parasites and require a growth medium containing living cells.