The total number of colonies mainly refers to the total number of colonies of a certain type of bacteria that grow on the sample under certain conditions. According to China’s standards and under aerobic conditions such as 37℃ for 48 hours, it is actually the total number of bacterial colonies that grow on ordinary nutrient AGAR plates. However, if the conditions do not meet its physiological requirements, it will be very difficult for it to reproduce and grow. Of course, what we need to pay attention to is that the total number of colonies is not the actual total number of all bacteria. It cannot distinguish the types of bacteria within and can be called the number of miscellaneous bacteria, the number of aerobic bacteria, etc.

The total number of colonies is not only an indicator for determining whether food is contaminated, but also an important indicator for testing water quality. It is more commonly used in online monitoring projects for medical wastewater.

Then, may I ask what harm will be caused if the total number of colonies in water exceeds the standard? It may cause adverse reactions such as vomiting and diarrhea, directly endangering human health problems (such as intestinal diseases, etc.). However, what needs to be emphasized here is that there is an essential difference between the total number of colonies and pathogenic bacteria; they are an inclusion relationship. The total number of colonies contains both pathogenic and beneficial bacteria. However, what is harmful to the human body are the pathogenic bacteria inside. These bacteria can disrupt the normal bacterial colony environment in the intestines. Some of them may be eliminated in the intestines, while others may remain in the body and cause damage to the body’s organs. The beneficial bacteria include lactic acid bacteria often mentioned in yogurt, etc. So, if the total number of colonies exceeds the standard, it means that the chance of pathogenic bacteria exceeding the standard increases, thereby raising the possibility of harm to human health.

The methods for testing the total number of colonies and the instruments used to detect its indicators. The operation steps for determining the total number of colonies are as follows: sample dilution – pour into petri dishes – culture for 48 hours – count report. The instrument used to detect the total number of colonies in water is called a “Water Quality total Number of Colonies Online Detector“.