SN/T 2552.6-2010Microbiological examination method for milk and milk products hygiene. Part 6: Detection of Citrobacter spp. (English PDF)

Foreword

SN/T 2552 "Milk and dairy products Hygienic science test methods" is divided into thirteen sections.

--- Part 1. Guidance on sampling;

--- Part 2. Preparation of test sample dilution;

--- Part 3. yeast, mold colony count;

--- Part 4. Psychrophile microbial colony counts;

--- Part 5. Salmonella testing;

--- Part 6. Citrobacter inspection;

--- Part 7. Enterobacter cloacae inspection;

--- Part 8. Proteus mirabilis and inspection;

--- Part 9. Klebsiella test;

--- Part 10. Enterobacter sakazakii immunofluorescence test;

--- Part 11. Bacillus cereus Isolation and counting;

--- Part 12. monocytogenes Listeria detection and counting;

--- Part 13. Pseudomonas Isolation and counting.

This section is SN/T 2552 Part 6.

This section drafted in accordance with GB/T 1.1-2009 given rules.

This section proposed and managed by the National Certification and Accreditation Administration Committee.

This section drafted by. China Inspection and Quarantine Science Research Institute, Shanxi People's Republic of China Exit Inspection and Quarantine, Beijing Agricultural Health Biotechnology Research Center.

1 Scope

This section SN/T 2552 specifies the most likely method of counting the number of Citrobacter milk powder.

This section applies to milk powder Citrobacter (genus or species) of the most probable number test.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein Member, undated references, the latest edition (including any amendments) applies to this document.

SN/T 1538.1 media preparation Guide - Part 1. General laboratory quality assurance prepared medium SN/T 1538.2 media preparation Guide Part 2. A Practical Guide to medium performance test SN/T 2552.1 milk and dairy hygiene microbiology test methods - Part 1. Guidance on sampling

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1 Citrobacter Citrobacterspp.

Latin name Citrobacter Citrobacter (Werkman and Gilen, 1932), Gram-negative facultative anaerobes. Bacillus, straight Diameter of about 1.0µm, length of 2.0µm ~ 6.0µm. Two metabolic breathing and fermentation types. Oxidase negative. Dynamic tests, ONPG test Positive, can utilize citrate, can liquefy gelatin, DNA enzyme test and VP tests were negative. According to "Bergey's Manual of Classification Bacteriology" Citrobacter into Citrobacter freundii (C.freundii), Coriolis Citrobacter (C.diversus) malonate and citrate without lever Bacteria (C.amalonaticus) three kinds.

4 Instruments, apparatus and standard strain

4.1 water bath. 45 °C ± 1 °C.

4.2 Incubator. 35 °C ~ 37 °C.

4.3 straw. 1mL, 5mL and 10mL.

4.4 inoculating loop. diameter 3mm.

4.5 Balance. a sense of the amount of 0.1g.

4.6 Sample dilution bottle. 100mL, 250mL and 2000mL flask or other suitable dilution bottles.

4.7 dish. diameter of 90mm.

4.8 standard strains of Citrobacter. Citrobacter freundii ATCC43864, Coriolis Citrobacter ATCC27156, no malonate Citrobacter ATCC25407 (or other traceable to the aforementioned strains standard strain).