Classificação do meio de cultura por componentes
According to the composition of the medium, it can be divided into natural medium and synthetic medium.
1. Natural medium contains natural substances whose chemical composition is not fully understood. Such as peptone, beef extract (powder), meat extract, corn syrup, blood, potato, etc. It is difficult to achieve stable and consistent quality between different batches of culture media prepared with such materials. Therefore, when selecting raw materials, it is necessary to indicate their commodity names, manufacturers and batch numbers. Small sample tests shall be conducted for raw materials from different sources first. This kind of culture medium has low cost and good bacterial reproduction. Generally, natural culture medium is mainly used for bacterial culture.
2. Synthetic medium is a medium composed of nutrients with known chemical components. According to the different nutritional requirements of microorganisms, it can be completely composed of inorganic salts or compounds, such as amino acids, sugars, purines, pyrimidines, vitamins, etc. the composition of which is known. As long as strict operation is carried out, the quality of each batch can be stable and consistent. This medium can be used to detect the effect of certain nutrients or drugs on microbial metabolism. Tissue and cell culture media are synthetic media. The cost of synthetic medium is high, and its price is several times or even tens of times that of similar natural medium. The synthetic medium containing only a few inorganic salts is only suitable for the cultivation of autotrophic bacteria, such as nitrobacteria and Thiobacillus. Most of the components of some media are nutrients with known chemical structure, and some or a few of them are essential nutrients with unknown chemical composition, which become semi synthetic media, such as hydrolyzed casein medium for pertussis vaccine production.