Organic raw material

In the field of research and application of microbiology, culture media play a crucial role. It is a specially formulated nutrient substrate that can provide a suitable growth environment for microorganisms and facilitate the accumulation of metabolites. In various works of modern microbiology, the application of artificial culture media is particularly extensive and frequent.

Because different types of microorganisms have their own unique nutritional characteristics, when conducting microbial culture, it is necessary to precisely select and ingeniously prepare the appropriate culture medium based on these characteristics. The components of the culture medium are rich and diverse. Among them, water is an indispensable basic component, which provides the necessary solvent environment for the growth and metabolism of microorganisms. Carbon-containing substances are important sources for microorganisms to obtain energy and construct their own structures. Nitrogen-containing substances play a crucial role in the synthesis of key biomolecules such as proteins and nucleic acids by microorganisms. In addition, inorganic salts and other growth factors are also important components of the culture medium. They participate in various physiological and biochemical reactions within microbial cells, maintaining the normal functions and metabolic balance of the cells.

However, merely including these basic components is far from enough. In order to meet the actual needs of microbial growth and reproduction or achieve other specific research and application purposes, multiple key factors must also be comprehensively considered in the process of preparing the culture medium. For instance, the regulation of osmotic pressure is of vital importance. An appropriate osmotic pressure can ensure that microbial cells maintain their normal shape and function, preventing damage to the cells caused by either excessively high or low osmotic pressure. The proportion of various nutrients also needs to be precisely controlled, as different microorganisms have different requirements for various nutrients. Only by achieving the optimal proportion can microorganisms grow well. The adjustment of pH value should not be ignored either. Different microorganisms adapt to different pH ranges. An appropriate pH value can create a stable growth environment for microorganisms. REDOX potential can also affect the growth of microorganisms, especially for those that are sensitive to oxygen. Appropriate REDOX potential conditions are a necessary prerequisite for their normal growth.

From the perspective of the physical properties of the culture medium, it can be classified into various types. Solid culture media usually have high stability and can provide a fixed growth surface for microorganisms, facilitating the observation of microbial colony morphology and operations such as separation and purification. Semi-solid culture media lie between solid and liquid, have a certain fluidity, and are often used to observe the motility and other characteristics of microorganisms. Liquid culture media are more suitable for large-scale microbial cultivation, enabling microorganisms to have full contact with nutrients, which is conducive to the rapid growth of microorganisms and the accumulation of metabolic products.

According to the chemical composition of the culture medium, it can be further classified into various types. Natural culture media are generally made from natural substances in nature. Their components are relatively complex, but they are rich in nutrients. Synthetic culture media are precisely formulated from nutrients with known chemical compositions, featuring clear components and strong repeatability. Semi-synthetic medium combines the characteristics of natural medium and synthetic medium. It not only contains some natural components but also adds some known chemical nutrients. The basic medium is the medium that provides the basic nutritional requirements for microorganisms and is suitable for the basic culture of most microorganisms. The enrichment medium is specially designed for the nutritional requirements of specific microorganisms and can selectively promote the growth of the target microorganisms. Complete culture medium contains all the nutrients required for the growth of microorganisms and can meet the growth needs of various microorganisms.

In addition, depending on the different uses of the culture medium, it can also be classified into selective culture media, identification culture media, inhibitory culture media, culture media for preserving bacterial strains, and production culture media, etc. Selective media can selectively promote the growth of target microorganisms and inhibit the growth of other microorganisms when multiple microorganisms are mixed. Identification media are used to distinguish different types of microorganisms. They are identified by observing the growth characteristics and physiological and biochemical reactions of microorganisms on specific media. Inhibitory media are mainly used to inhibit the growth of unwanted microorganisms while allowing the growth of target microorganisms. The culture medium for preserving microbial strains is a specially designed medium for the long-term preservation of microbial strains, which can maintain the activity and survival ability of microorganisms. Production medium is the medium used for large-scale production of microbial metabolites and needs to be optimized and adjusted according to production requirements.

After the culture medium is prepared, it must undergo strict sterilization treatment before use. This is to prevent contamination by external miscellaneous bacteria, ensure the purity of the culture medium, and thereby provide a sterile environmental condition for the cultivation of microorganisms.

Peptone, as an important nutrient, has wide applications in the field of microbial culture. It is a pale yellow powder-like substance made by hydrolyzing meat, casein, gelatin or protein with acid, alkali or protease, and then through a drying process. When proteins are decomposed by the action of acids, bases or proteases, peptones can also be formed. It is worth noting that one of the initial digestion products of proteins in the stomach is peptone.

The composition of peptone is rather complex and rich, mainly containing organic components such as hydroxyl groups, peptone, polypeptides, dipeptides, and various amino acids. In addition, it also contains a small amount of metal ions such as chlorine, sodium, potassium, calcium, magnesium, iron, zinc, tin, copper, lead and manganese. These rich nutrients enable peptone to provide comprehensive nutritional support for the growth of microorganisms.

As early as 1880, Nagri discovered an important phenomenon while conducting bacterial culture experiments: after adding this special substance to the bacterial culture medium, the growth condition of the bacteria was significantly improved and they grew very well. Based on this discovery, Nagri named this incomplete protein hydrolysis product peptone for the first time.

In practical applications, various animal and plant proteins can be used to produce peptone. However, peptones from different sources vary in terms of nutritional components and applicability. For instance, fish protein has a relatively complete range of amino acid types, which can better meet the various amino acid requirements for microbial growth. Therefore, it is one of the important raw materials for manufacturing peptone.

Peptone is rich in organic nitrogen compounds, which are important nutrients necessary for the growth of microorganisms. Meanwhile, it also contains some nutrients such as vitamins and sugars, which can further meet the nutritional needs of microorganisms. For this reason, peptone can be used as the main raw material for microbial culture media and plays an extremely important role in the fields of microbiology and pharmaceuticals, with broad application prospects.

Plant peptones, especially soybean peptones, have their unique advantages and application scenarios. It is specifically used for culturing specific types of microorganisms such as Streptococcus, pneumococcus and Brucella. Its nutritional components are rich and diverse. It not only provides sufficient nutritional support for these microorganisms but also can be used as a fermentation raw material in industrial production, playing an important role in large-scale industrial fermentation processes.