Testing of fecal colium

(i) relationship between fecal coli and E. coli
according to the standard method of testing
microbial
promulgated by the State for food hygiene (GB4789. 3-94), faecal coliform (Fae-cal coliform) refers to a group of fermented lactose can produce acid gas at 44 degrees C24 h and use tryptophan to produce indigo, oxygen demand and anaerobic Glide-negative Bacillus aureus. Type I of E. coli in Table 5-3 is a fecal coli group.
source of fecal colium is feces, so only fecal coli is the exact indicator of fecal contamination. In the samples tested, if fecal E. coli is present, it is also counted in E. coli testing. Therefore, there are also people who refer to the number of E. coli groups as the total number of E. coli groups.
In recent years, it has been suggested that two types of bacteria, E. coli and fecal coli, should be used as indicators of food hygiene bacteria, if both E. coli and fecal colium are high, more consideration should be given to near-term pollution;
(ii) the test procedure
1. The dilution of the
the same as the colium.
2． 44 degrees C lactose fermentation test
the sample inoculated with sterile operation in the lactose bile salt fermentation tube (1 mL or more 1 mL and 1 mL or less, with a single lactose bile salt fermentation tube), placed (44 soil 0.5) in the water bath,
culture
(24 soil 2) h. After culture, if all lactose bile salt fermentation tubes do not produce gas, it can be reported as negative;
3． The test
all the gas-producing fermentation tubes were planted on the agar plate of
red
blue. And at the same time inoculated protein water, placed (44 soil 0.5) culture 24 h. After culture, the above-mentioned plate to observe the growth of typical colonies, fecal colium bacteria in the Ihongmei blue agar plate colonies are purple-black, metallic luster, while doing Gel staining mirror examination. The reagent of the indigo substation
in
water was used to observe the reaction of the indigo substation.
4． Results The
positive for the substrate and the typical colonies on the tablet were confirmed to be positive for fecal coli.
5． Report
based on the number of positive tubes confirmed to be fecal colium, check the MPN search form and report the most likely number of 100 mL (g) fecal coli colonies.
(iii) Rapid testing of colium ga
E. coli test method (national standard) using fermentation method (lactose fermentation test, separation culture, confirmation test), it takes 3 d. In order to facilitate the actual needs of rapid monitoring of food hygiene, the Coligroup of E. coli research has carried out a lot of research in this regard over the years, and has made some achievements. In May 1985, a meeting was held in Xining on the rapid testing methods of E. coli groups, summarizing the experience of rapid testing of E. coli groups in China in recent years, and passing the
statistics of 1099 samples (including milk and dairy products, cold drinks, meat products, soy products, condiments, beer, pastries, etc.) in 24 units
. Analysis, it can be considered that the current domestic application of the three rapid test methods (TTC color method, DC
test tube
method and paper chip method) are high accuracy and compliance rate, similar to the fermentation method results, and has the advantages of fast, simple, 18 b124 h reportable results. The three rapid test methods are not significantly different from the fermentation method in the test results, and each of the three methods has its own holding point, in practice, according to the specific situation can be selected for the use of tough sieve.