How to detect the total number of bacteria?

At present, the method stipulated in the national standard for total bacterial count detection is the plate counting method, and its inspection method is as follows:

Inoculate 1 ml water sample or diluted water sample into liquefied nutrient agar medium heated in a glass plate, cool and solidify, and then culture at 37℃ for 24 hours. The total number of bacteria is the number of colonies on the culture medium or multiplied by the dilution multiple of the water sample.

Some countries set the culture temperature at 35℃ or other temperatures, while others set the culture time at 48 hours. This method has high precision, but it takes a long time and is difficult to meet the actual work needs.

In order to simplify the detection procedure and shorten the detection time, scholars at home and abroad have done a lot of research on rapid detection methods, and put forward some detection methods, such as impedance detection, SIMPLETM full plate counting, micro-colony technology, paper method and so on. , and achieved certain results, but the detection time is still more than 4 hours.

Based on the analysis of the existing research results, this study puts forward a method for directly detecting the total number of bacteria after filtration membrane dyeing, and the specific steps are as follows:

Collecting bacteria with a bacteria collector → dyeing on the membrane → counting under an oil mirror → calculating the concentration of bacteria solution according to the formula. The experimental results show that there is no significant difference between this method and the traditional plate culture method, and the detection time is about 65438 0 h, which is a rapid method to detect the total number of bacteria.

Extended data:

Common bacteria in water can be roughly divided into three categories:

Bacteria in natural water. The common bacteria are Pseudomonas fluorescens and Pseudomonas aeruginosa, which are generally considered to be non-pathogenic to healthy people.

2. Soil bacteria. When there is more surface water during flood period or after rainstorm. They don't live in water for a long time and are easily removed in the process of water treatment. Iron bacteria and sulfur bacteria that corrode water pipes also belong to this category.

3. Intestinal bacteria. They live in the intestines of warm-blooded animals, so their feces are rich. This kind of bacteria is found in water and can be considered to be contaminated by feces. Pathogenic intestinal bacteria include salmonella (typhoid and paratyphoid), anthrax type B, Shigella dysenteriae and Vibrio cholerae.

Baidu Encyclopedia-Total Bacteria