Detailed introduction Moveable Uvss,Car Inspection Machine,Uvis Scanned Images,Under Car Inspection Machine Shenzhen Unisec Technology Co.,ltd , https://www.uniqscansecurity.com The newly released Shigella national standard GB_4789.5-2012 (national food safety standard _ food microbiology test _ Shigella test method) was implemented on July 17, 2012, the new national standard has significant changes in the enrichment section It is required to enrich bacteria overnight under anaerobic conditions. Many microbiologists are discussing ways to achieve anaerobic enrichment. Because of the use of triangular bottles, reagent bottles or homogenized bags, the bacteria can be enriched in the container, depending on the sample capacity and equipment. Comprehensive consideration of various factors such as affordability. Chongqing Jiangxue Technology recommends several solutions for customers who have the need to detect Shigella.
The original GB/T4789.5-2003 standard was invalidated from the date of implementation of the standard.
In order to improve the detection rate of Shigella in food and reduce the operator's operation requirements, the adjustment of the enrichment process is the biggest change of this new standard.
The main differences between the two national standard methods for enrichment are shown in the following table:
The ultimate goal of changing the enrichment culture method is to minimize the effects of the background of the bacteria in the food sample on the culture.
1, anaerobic environment 41.5 ° C culture, can eliminate aerobic bacteria and most of the heat-tolerant anaerobic bacteria and facultative anaerobic bacteria interference;
2. The use of Shigella enrichment broth-neomycin for enrichment can eliminate the interference of Gram-positive bacteria and some Gram-negative Enterobacteria (such as Proteus);
While reducing the background of the bacteria, it also reduces the competitive inhibition of a small number of Shigella in the process of enrichment, which can effectively increase the amount of Shigella amplification and contribute to further separation. And identification.
The anaerobic enrichment solution is different from the conventional anaerobic culture. The enrichment culture in this standard is carried out in a sterile conical flask or a sterile homogenized bag. Therefore, the anaerobic bag cannot be used due to the volume limitation, so the following is recommended. Professional solutions:
Solution 1: The laboratory with 30~50 samples per day is recommended to be equipped with AG300 anaerobic workstation.
Model AG300
Maximum culture capacity: 50 (250ml standard conical flask)
30 (500 ml standard conical flask)
Transmission capacity: 2 (250/500ml standard conical flask)
(* The diameter of the bottom of the flask should be less than 100mm and the height should be less than 200mm)
Solution two:
The laboratory with a small amount of daily sample detection (≤30 parts), the A30 anaerobic culture system, requires the anaerobic tank to be cultured in a biochemical incubator.
Model A30 Anaerobic culture system with 20L culture tank Maximum culture capacity: 20 (250ml standard conical flask)
A solution to the new national standard anaerobic conditions for the detection of Shigella
Shigella detection new national standard anaerobic conditions enrichment solution
New national standard
On May 17, 2012, the Ministry of Health of the People's Republic of China issued GB 4789.5-2012 "Food Safety Country"
Standard Food Microbiological Testing Shigella Test Method, implemented on July 17, 2012.
Interpretation of GB4789.5-2012
GB4789.5-2003
GB4789.5-2012
Enrichment medium
GN enrichment broth
Shigella enrichment broth - novomycin
Sampling operation
Sterile homogenizer or mortar
Sterile homogenizer or tapping homogenizer
Enrichment culture conditions
37 ° C, aerobic culture for 6-8 hours
41.5 ° C, anaerobic culture for 16 to 20 hours
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