GB 4789.40-2024 English PDF (GB4789.40-2024)

This Standard specifies the examination method for Cronobacter spp. in food. This Standard is applicable to the examination of cronobacter in formula foods and supplementary foods for infants and young children, milk and dairy products and their raw materials. 2 Equipment and Materials In addition to the routine sterilization and culture equipment of the microbiology laboratory, other equipment and materials are as follows. 2.1 Constant-temperature incubator: 36 ?C ? 1 ?C, 41.5 ?C ? 1 ?C. 2.2 Refrigerator: 2 ?C ~ 5 ?C, ?20 ?C. 2.3 Constant-temperature water bath: 41.5 ?C ? 1 ?C. 2.4 Balance: with a division value of 0.1 g and 0.01 g. 2.5 Oscillator. 2.6 Sterile pipette: 1 mL (with a scale of 0.01 mL), 10 mL (with a scale of 0.1 mL) or micropipette and tip. 2.7 Sterile container: with a capacity of 100 mL, 200 mL and 2,000 mL. 2.8 Sterile petri dish: with a diameter of 90 mm. 2.9 pH meter or pH colorimetric tube or precision pH test paper. 2.10 Microbial biochemical identification system. 2.11 PCR instrument. 2.12 Centrifuge: with a rotation speed ? 12,000 r/min. 2.13 Gel imaging system or UV detector. 2.14 Agarose horizontal electrophoresis instrument or capillary electrophoresis instrument. GB 4789.40-2024 www.ChineseStandard.net ? Buy True-PDF ? Auto-delivery. Page 5 of 21 2.15 PCR reaction tube. 2.16 1.5 mL centrifuge tube. 2.17 10 ?L inoculation loop. 3 Culture Media and Reagents 3.1 Buffered peptone water, BPW: see A.1. 3.2 Modified lauryl sulfate tryptose broth-vancomycin medium, mLST-Vm: see A.2. 3.3 Cronobacter chromogenic medium. 3.4 Trypticase soy agar, TSA: see A.3. 3.5 Biochemical identification kit. 3.6 Oxidase reagent: see A.4. 3.7 L-lysine decarboxylase medium: see A.5. 3.8 L-ornithine decarboxylase medium: see A.6. 3.9 L-arginine dihydrolase medium: see A.7. 3.10 Carbohydrate fermentation medium: see A.8. 3.11 Simon¡¯s citrate medium: see A.9. 3.12 The internal transcribed spacer (its) PCR primers are shown in Table 1. The gene enrichment target refer...