Complex media are composed of what type of materials?

Complex media are composed of raw materials that are usually undefined. This type of media includes a variety of ingredients such as extracts from yeast, beef, or other sources that provide a wide array of nutrients, including vitamins, amino acids, carbohydrates, and minerals necessary for the growth of many types of microorganisms. The complexity and variability of the components make the media "complex," as the exact composition can vary between batches and is not typically precisely defined.

Using complex media is advantageous for cultivating a broad range of microorganisms, especially those that have not been well characterized and for which specific nutrient needs are not known. In contrast, synthetic media are made from defined, known chemical compounds, providing a uniform solution with precisely determined concentrations, which is not the case with complex media.