Analysis Of Detection Method Of Bacillus Cereus In Food And Study On Establishment Of The Improved Method

Bacillus cereus is a common food contaminating bacteria and opportunistic pathogen, event associated with a large number of food poisoning, seriously impacting on people’s health and safety. At present, there is no clear Bacillus cereus set limit value in our country related food standard, which cause to the production control of the bacteria can not follow. Furthermore, due to the presence of inconsistency detection method between international method and ours, domestic test results appear large difference from foreign.This topic in the Xinjiang Shihezi area collected raw milk, meat, street snacks and night leftovers in 4categories including 40 samples. Bacillus cereus detection results showed that 4 types of foods were detected in 40 samples, and the average positive rate was 22.5%. Pollution levels of Bacillus cereus in positive samples ranged from 1.5×102 CFU/g(ml) to 3×105 CFU/g(ml).Analysis results of detection methods of domestic and foreign of Bacillus cereus: GB/T 4789.14-2003,SN/T 0176-2013, EN ISO 7932-2004, proving that GB detection method is easy to be polluted, that colony is continuous and difficult to count, that colony grows rapidly affecting the count accuracy, and is susceptible to other bacteria affecting the detection sensitivity and other defects; MPN count method in SN detection method stipulate indefinitely the individual steps. It may affect the accuracy of results due to undetected results, and workload of it is very large, costing too much; ISO detection method is simple and convenient, yet only limits to detect suspected Bacillus cereus, but cannot distinguish between Bacillus cereus and other very similar but relatively rare Bacillus, therefore may lead to errors and omissions.Experience obtained from using API 50 CHB biochemical identification system, can confirm the factors affecting the accuracy of identification system including culture purity, bacterial suspension concentration, at the same time, the API 50 CHB system cannot distinguish Bacillus cereus and Bacillus thuringiensis, so protein toxin crystal test is still needed.Combined with Bacillus cereus related detection methods at home and abroad, refering to other counting method in microbiological examination of food hygiene, we establish the improved Bacillus cereus detection methods, which based on the testing of effectiveness and accuracy, that can achieve the specificity and accuracy of the same with the existing domestic and international examination method, and can be used for detection of Bacillus cereus in food. Compared with other detection methods, the improved method has the characteristics of simple, accurate, economical, which provided a new idea for the detection of Bacillus cereus in food.