BS ISO 15213 pdf download Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of sulfite- reducing bacteria growing under anaerobic conditions
This International Standard specifies a horizontal method for the enumeration of sulfite-reducing bacteriagrowing under anaerobic conditions. lt is applicable to
– products intended for human consumption and the feeding of animals, and- environmental samples in the area of food production and food handling.
The following referenced documents are indispensable for the application of this document. For datedreferences, only the edition cited applies. For undated references, the latest edition of the referenced document(including any amendments) applies.
ISO 6887-1:1999，Microbiology of food and animal feeding stuffs — Preparation of test samples，initialsuspension and decimal dilutions for microbiological examination—Part 1: General rules for the preparation ofthe initial suspension and decimal dilutions
ISO 8261,Milk and milk products —General guidance for the preparation of test samples,initial suspensionsand decimal dilutions for microbiological examination
ISO 7218:1996，Microbiology of food and animal feeding stuffs —General rules for microbiologicalexaminations
ISO 7218:1996/Amd.1:2001, Microbiology of food and animal feeding stuffs — General rules for microbiologicalexaminations -Amendment 1
ISO/TS 11133-1, Microbiology of food and animal feeding stuffs —Guidelines on preparation and production ofculture media— Part 1: General guidelines on quality assurance for the preparation of culture media in thelaboratory
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.3.1
sulfite-reducing bacteria growing under anaerobic conditions
bacteria forming countable typical colonies under the conditions specified in this International Standard
4.1 Two agar plates (or tubes) are prepared, using iron sulfite medium, and using a specified quantity of thetest sample if the initial product is liquid, or using a specified quantity of an initial suspension in the case of otherproducts.
Two other agar plates (or tubes) are prepared, under the same conditions, using decimal dilutions of the testsample or the initial suspension.
4.2The plates (or tubes) are incubated under anaerobic conditions at forto(final reading after ), or possibly at if thermophilic bacteria are suspected. Typical black-coloured coloniesare counted.The black colour of the colonies and the surrounding zone is due to the formation of iron(ll) sulfideas a result of the reaction between sulfide ions and trivalent iron [Fe(IIl)] present in the medium.
4.3 The number of sulfite-reducing bacteria per millitre or per gram of sample is calculated from the numberof colonies obtained on the plates (or tubes).
5 Culture medium and diluent
For current practices,see lSO 7218.
5.1 Plate count medium: lron sulfite agar
Enzymatic digest of casein 15 g
Pancreatic digest of soya 5 g
Yeast extract 5 g