Total number of colonies

The total number of colonies is the total number of bacterial colonies grown per gram (per milliliter) of the test sample under certain conditions (such as aerobic conditions, nutritional conditions, pH, culture temperature and time, etc.). According to national standard methods, that is, the total number of bacterial colonies that can be grown on ordinary nutrient agar plates under aerobic conditions for 48 hours at 37 ° C, so anaerobic or microaerobic bacteria, those with special nutritional requirements, and non- mesophilic Bacteria, because existing conditions cannot meet their physiological needs, are difficult to reproduce and grow. Therefore, the total number of colonies does not represent the total number of all bacteria in the actual, the total number of colonies can not distinguish the type of bacteria, so it is sometimes called the number of miscellaneous bacteria, aerobic bacteria and so on. Bacterial colonies are the growths that can be recognized by the naked eye, formed by the growth and reproduction of bacteria on a solid medium. It is a collection of tens of thousands of identical bacteria. When the sample is diluted to a certain degree and mixed with the culture medium, under certain culture conditions, each bacterial cell capable of growth and reproduction can form a visible colony on the plate.