Generally speaking, high-quality microbial seeds should have the conditions of matching biomass and inoculum, synchronization of bacterial growth cycle, strong physiological activity and adaptability, and no contamination by other microorganisms. The culture medium, culture conditions, seed age and seed culture stages have a great influence on the quality of seeds. Among them, the raw materials of culture medium are not only related to the overall fermentation efficiency, but also importand for costs. The choice of nitrogen source in the growth and metabolism of microorganisms is very important. Commonly used organic nitrogen sources in industrial production include peanut meal, soybean meal, cottonseed meal, corn steep liquor, corn gluten meal, peptone, inactive yeast, yeast extract, fish meal, silkworm pupa meal, waste fungus, etc.

On one hand, the complex composition of organic nitrogen sources can affect the fermentation process from many aspects. On the other hand, some organic nitrogen sources are unstable, as the components are differences between different manufacturers and different batches. Therefore, the selection and use of organic nitrogen sources are very critical during the fermentation process, especially during the stage of microbial seed propagation. It is very necessary to select a more refined organic nitrogen source in the seed propagation stage than in the fermentation stage to improve the quality and stability of the seeds and increase the efficiency of fermentation production.

In addition, the organic nitrogen source of baker's yeast extract is most suitable for the efficient propagation of microbial seeds. It can be matched with other nutrients to increase the specific growth rate , Shorten the logarithmic growth period. The baker's yeast extract has four characteristics of safety, stability, high efficiency and cleanliness in propagation of microbial seeds, and widely used.

As a high-quality organic nitrogen source, baker’s yeast extract from pure cultured baker's yeast is rich in peptides, amino acids, vitamins, trace elements, nucleotides, etc., and is optimally combined with other nutrient components to ensure high quality and quantity of seeds. It is also conducive to the optimization of the subsequent fermentation process and high yield. It is the perfect choice for fermentation factory and microbiology researcher to carry out high-quality propagation of strains.