EN ISO 7932:2004/A1:2020
(Amendment)Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of presumptive Bacillus cereus - Colony-count technique at 30 degrees C - Amendment 1: Inclusion of optional tests (ISO 7932:2004/Amd 1:2020, Corrected version 2020-08)
Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of presumptive Bacillus cereus - Colony-count technique at 30 degrees C - Amendment 1: Inclusion of optional tests (ISO 7932:2004/Amd 1:2020, Corrected version 2020-08)
Mikrobiologie von Lebensmitteln und Futtermitteln - Horizontales Verfahren zur Zählung von präsumtivem Bacillus cereus - Koloniezählverfahren bei 30 °C - Änderung 1: Aufnahme optionaler Testmethoden (ISO 7932:2004/Amd 1:2020, korrigierte Fassung 2020-08)
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Microbiologie des aliments - Méthode horizontale pour le dénombrement de Bacillus cereus présomptifs - Technique par comptage des colonies à 30 degrés C - Amendement 1: Ajout de tests optionnels (ISO 7932:2004/Amd 1:2020, Version corrigée 2020-08)
Mikrobiologija živil in krme - Splošno navodilo za štetje domnevno prisotnih Bacillus cereus - Štetje kolonij pri 30 °C - Dopolnilo A1: Vključitev izbirnega preskusa (ISO 7932:2004/Amd 1:2020)
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Standards Content (Sample)
SLOVENSKI STANDARD
01-junij-2020
Mikrobiologija živil in krme - Splošno navodilo za štetje domnevno prisotnih
Bacillus cereus - Štetje kolonij pri 30 °C - Dopolnilo A1: Vključitev izbirnega
preskusa (ISO 7932:2004/Amd 1:2020)
Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration
of presumptive Bacillus cereus - Colony-count technique at 30 degrees C - Amendment
1: Inclusion of optional tests (ISO 7932:2004/Amd 1:2020)
Mikrobiologie von Lebensmitteln und Futtermitteln - Horizontales Verfahren zur Zählung
von präsumtivem Bacillus cereus - Koloniezählverfahren bei 30 °C - Änderung 1:
Aufnahme optionaler Testmethoden (ISO 7932:2004/Amd 1:2020)
Microbiologie des aliments - Méthode horizontale pour le dénombrement de Bacillus
cereus présomptifs - Technique par comptage des colonies à 30 degrés C -
Amendement 1: Ajout de tests optionnels (ISO 7932:2004/Amd 1:2020)
Ta slovenski standard je istoveten z: EN ISO 7932:2004/A1:2020
ICS:
07.100.30 Mikrobiologija živil Food microbiology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 7932:2004/A1
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2020
EUROPÄISCHE NORM
ICS 07.100.30
English Version
Microbiology of food and animal feeding stuffs - Horizontal
method for the enumeration of presumptive Bacillus
cereus - Colony-count technique at 30 degrees C -
Amendment 1: Inclusion of optional tests (ISO
7932:2004/Amd 1:2020)
Microbiologie des aliments - Méthode horizontale pour Mikrobiologie von Lebensmitteln und Futtermitteln -
le dénombrement de Bacillus cereus présomptifs - Horizontales Verfahren zur Zählung von präsumtivem
Technique par comptage des colonies à 30 degrés C - Bacillus cereus - Koloniezählverfahren bei 30 °C -
Amendement 1: Ajout de tests optionnels (ISO Änderung 1: Aufnahme optionaler Testmethoden (ISO
7932:2004/Amd 1:2020) 7932:2004/Amd 1:2020)
This amendment A1 modifies the European Standard EN ISO 7932:2004; it was approved by CEN on 22 March 2020.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for inclusion of
this amendment into the relevant national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This amendment exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7932:2004/A1:2020 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 7932:2004/A1:2020) has been prepared by Technical Committee ISO/TC 34
"Food products" in collaboration with Technical Committee CEN/TC 463 “Microbiology of the food
chain” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2020, and conflicting national standards shall
be withdrawn at the latest by October 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 7932:2004/Amd1:2020 has been approved by CEN as EN ISO 7932:2004/A1:2020
without any modification.
INTERNATIONAL ISO
STANDARD 7932
Third edition
2004-06-15
AMENDMENT 1
2020-03
Microbiology of food and animal
feeding stuffs — Horizontal method
for the enumeration of presumptive
Bacillus cereus — Colony-count
technique at 30 degrees C
AMENDMENT 1: Inclusion of optional
tests
Microbiologie des aliments — Méthode horizontale pour le
dénombrement de Bacillus cereus présomptifs — Technique par
comptage des colonies à 30 degrés C
AMENDEMENT 1: Ajout de tests optionnels
Reference number
ISO 7932:2004/Amd.1:2020(E)
©
ISO 2020
ISO 7932:2004/Amd.1:2020(E)
© ISO 2020
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ISO 7932:2004/Amd.1:2020(E)
Foreword
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This document was prepared by ISO Technical Committee TC 34, Food products, Subcommittee SC 9,
Microbiology, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 463, Microbiology of the food chain, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
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ISO 7932:2004/Amd.1:2020(E)
Microbiology of food and animal feeding stuffs —
Horizontal method for the enumeration of presumptive
Bacillus cereus — Colony-count technique at 30 degrees C
AMENDMENT 1: Inclusion of optional tests
In the Scope
Designate the existing NOTE as NOTE 1 and add the following new NOTE:
[21][22]
NOTE 2 The diversity within the Bacillus cereus group is large with 7 phylogenetic groups and a growing
number of species.
After 9.4
Add the following new subclause 9.5:
9.5 Optional tests
9.5.1 General
All the tests mentioned below are optional and intended for complementary investigations
(i.e. epidemiological) on isolated Bacillus cereus group strains obtained in 9.4.1, following the procedures
described in Annexes C to F.
In this amendment, the term “B. cereus group” is used instead of “presumptive B. cereus”, as it is
[28]
scientifically more precise, as explained in the EFSA scientific opinion published in 2016 .
9.5.2 Detection of cytK-1 or cytK-2 gene variants of the gene encoding Cytotoxin K
Some strains within the B. cereus group bacteria carry one of the two variants found for the gene
[17][22]
encoding Cytotoxin K, cytK-1 and cytK-2. The cytK-1 gene is specific to Bacillus cytotoxicus and
[20]
thus constitutes the possibility to rapidly identify B. cytotoxicus . The procedure in Annex C describes
a validated PCR method that targets both cytK gene variants and, if present, indicates which of the two
forms is present. It also allows confirmation of isolates as B. cytotoxicus.
9.5.3 Detection of Bacillus cereus group strains able to produce cereulide
Some strains within the B. cereus group bacteria are able to produce a heat-stable dodecadepsipeptide,
named cereulide. This cereulide, when produced in food, can cause an emetic food poisoning syndrome.
[10]
NOTE The method for cereulide quantification is described in ISO 18465 .
[16]
A cereulide peptide synthetase (ces) gene is involved in the non-ribosomal synthesis of cereulide .
The procedure in Annex D describes a rapid and validated PCR method that targets the ces gene.
9.5.4 Motility test for B. anthracis screening
The motility test described in Annex E allows for screening for presumptive B. anthracis among isolated
B. cereus group bacteria.
NOTE This test has nevertheless strong limitations as indicated in Annex E (see E.1 and Table E.1).
ISO 7932:2004/Amd.1:2020(E)
9.5.5 Microscopic examination of the parasporal crystal from Bacillus thuringiensis
B. thuringiensis, one of the B. cereus group species, can be distinguished from the other species of this
group by the microscopic examination of the parasporal crystal formation.
The procedure for the examination of the parasporal crystal formation is described in Annex F.
After Annex B
Add the following as Annexes C, D, E and F.
2 © ISO 2020 – All rights reserved
ISO 7932:2004/Amd.1:2020(E)
Annex A
(informative)
Polymerase chain reaction for the detection of cytK-1 or cytK-2
gene variants of cytotoxin K in isolated strains of Bacillus cereus
group and identification of Bacillus cytotoxicus
A.1 General
The chromosomally located cytK-2 gene encodes cytotoxin K, an enterotoxin that is present in B. cereus
[22]
sensu stricto and B. thuringiensis strains .
[29]
Presence of cytK-2 genes are also mentioned in strains of other B. cereus group species . CytK-1 gene
is a variant of cytK-2 gene due to a marked polymorphism and encodes to a more cytotoxic form of
[18]
cytotoxin K that is present only in B. cytotoxicus .
This method is applicable to well-isolated colonies of B. cereus group strains, after appropriate
preparation of the DNA.
A.2 Principles
A.2.1 General
The method comprises the following consecutive steps:
a) nucleic acid extraction;
b) amplification of target gene and interpretation.
A.2.2 Nucleic acid extraction
Bacterial cells are harvested from well isolated colonies and the nucleic acid is extracted for use in PCR
reaction.
A.2.3 Amplification of target gene and interpretation
The extracted nucleic acid is selectively amplified using PCR. Detection of the PCR products is achieved
by electrophoresis on agarose. Interpretation is deduced from presence or absence of the expected band.
A.3 Reagents
A.3.1 General
All reagents needed for this annex are molecular grade reagents and consumables suitable for molecular
[11] [12]
biology. They shall be used as given in ISO 20837 and ISO 20838 .
A.3.2 Nucleic acid extraction
Nucleic acid extraction procedure and reagents appropriate for Gram-positive bacteria shall be used.
Commercial kits can also be used.
ISO 7932:2004/Amd.1:2020(E)
A.3.3 Reagents for PCR
[14] [12]
Refer to ISO 22174 and ISO 20838 .
A.3.4 Primers
The primers used for detection of cytotoxin K genes are listed in Table C.1.
Table C.1 — Sequences of oligonucleotides, characteristics and re
...
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