oSIST prEN 18279:2026
(Main)Soil improvers and growing media - Enumeration of enterococci
Soil improvers and growing media - Enumeration of enterococci
This document specifies a method for the enumeration of enterococci in soil improvers and growing media. This document is applicable to material in solid form (including pre-shaped growing media) and liquid form.
This document is applicable to fertilizing product blends, where a blend is a mix of two or more fertilising products belonging to the categories of fertilizers, liming material, soil improvers, growing media, inhibitors and plant biostimulants, and where soil improvers and/or growing media comprise the highest percentage in the blend by mass or volume, or in the case of liquid form by dry mass. If soil improvers and/or growing media do not comprise the highest percentage in the blend, the European Standard for the highest percentage in the blend applies. In case a blend is composed of fertilising products in equal quantity, the user of the standard decides which standard to apply.
NOTE 1 A soil improver or a growing medium consists of a single bulky (volume-building) component or a mix of bulky (volume-building) components (for example peat, wood fibres, coconut coir, compost, expanded perlite).
NOTE 2 This method has been validated in an interlaboratory study with specific products that were present on the market during the study (Annex C).
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung von Enterococcacae
Amendements du sol et supports de culture - Dénombrement des Enterococcaceae
Izboljševalci tal in rastni substrati - Ugotavljanje števila enterokokov
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2026
Izboljševalci tal in rastni substrati - Ugotavljanje števila enterokokov
Soil improvers and growing media - Enumeration of enterococci
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung von Enterococcacae
Amendements du sol et supports de culture - Dénombrement des Enterococcaceae
Ta slovenski standard je istoveten z: prEN 18279
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2026
ICS 65.080
English Version
Soil improvers and growing media - Enumeration of
enterococci
Amendements du sol et supports de culture - Bodenverbesserungsmittel und Kultursubstrate -
Dénombrement des Enterococcaceae Bestimmung von Enterococcacae
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 223.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN 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, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18279:2026 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 6
5 Culture media and reagents . 6
6 Equipment and consumables . 6
7 Sampling . 7
8 Preparation of the test sample . 7
9 Procedure . 7
9.1 General. 7
9.2 Preparation of the initial suspension and decimal dilutions . 7
9.3 Inoculation and incubation on Slanetz-Bartley agar . 7
9.4 Enumeration of colonies . 8
9.5 Confirmation . 8
9.5.1 General. 8
9.5.2 Confirmation of selected typical colonies on BEA agar . 8
9.5.3 Catalase test (optional) . 9
10 Expression of results . 9
11 Validation of the method . 10
11.1 Validation in accordance with ISO 5725-5. 10
11.2 Performance characteristics. 10
12 Test report . 10
13 Quality assurance . 11
Annex A (normative) Flow diagram of the procedure . 12
Annex B (normative) Composition and preparation of culture media and reagents . 13
Annex C (informative) Performance characteristics of the method . 16
Annex D (informative) Alternative methods to transfer colonies from Slanetz-Bartley agar
to Bile Esculin Azide agar . 19
Bibliography . 20
European foreword
This document (prEN 18279:2026) has been prepared by Technical Committee CEN/TC 223 “Soil
improvers and growing media”, the secretariat of which is held by NEN.
This document is currently submitted to the CEN Enquiry.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
Introduction
This document has been developed to enumerate enterococci in soil improvers and growing media in
order to control certain imposed hygienic requirements. The method described in this document is based
on EN ISO 7899-2 and ISO/CD 21722.
Enterococci are considered indicator germs for faecal contamination (intestinal enterococci).
Consequently, they can be used as a parameter to evaluate the sanitation process during the
manufacturing process of soil improvers or growing media. The presence or absence of enterococci does
not reflect the presence or absence of other pathogens in the material tested.
Enterococci include several species of the genus Enterococcus. These bacteria occur ubiquitously in the
environment (water, soil), in animals and in humans (in the normal intestinal flora).
WARNING — In order to safeguard the health of laboratory personnel, it is essential that tests for the
enumeration of enterococci are only undertaken in properly equipped laboratories, under the control of
a skilled microbiologist, and that great care is taken in the disposal of all incubated materials. Persons
using this document should be familiar with normal laboratory practice. This document does not purport
to address all of the safety aspects, if any, associated with its use. It is the responsibility of the user to
establish appropriate safety and health practices.
1 Scope
This document specifies a method for the enumeration of enterococci in soil improvers and growing
media. This document is applicable to material in solid form (including pre-shaped growing media) and
liquid form.
This document is applicable to fertilizing product blends, where a blend is a mix of two or more fertilising
products belonging to the categories of fertilizers, liming material, soil improvers, growing media,
inhibitors and plant biostimulants, and where soil improvers and/or growing media comprise the highest
percentage in the blend by mass or volume, or in the case of liquid form by dry mass. If soil improvers
and/or growing media do not comprise the highest percentage in the blend, the European Standard for
the highest percentage in the blend applies. In case a blend is composed of fertilising products in equal
quantity, the user of the standard decides which standard to apply.
NOTE 1 A soil improver or a growing medium consists of a single bulky (volume-building) component or a mix
of bulky (volume-building) components (for example peat, wood fibres, coconut coir, compost, expanded perlite).
NOTE 2 This method has been validated in an interlaboratory study with specific products that were present on
the market during the study (Annex C).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 12579, Soil improvers and growing media - Sampling
prEN 13040-2, Soil improvers and growing media — Sample preparation — Part 2: Sample preparation
for microbiological examination
prEN 17732, Soil improvers and growing media — Terminology
EN ISO 7218, Microbiology of the food chain - General requirements and guidance for microbiological
examinations (ISO 7218)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in prEN 17732, prEN 13040-2 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
presumptive enterococci
bacteria which are able to reduce 2,3,5-triphenyltetrazolium chloride to formazan on the surface of a
selective culture medium containing sodium azide (Slanetz-Bartley agar) under the conditions specified
in this document
Under preparation. Stage at time of publication: prEN 13040-2:2025.
Under preparation. Stage at time of publication: prEN 17732:2025.
3.2
enterococci
bacteria which are able to reduce 2,3,5-triphenyltetrazolium chloride to formazan on the surface of a
selective culture medium containing sodium azide (Slanetz-Bartley agar) and to hydrolyse esculin at
44 °C ± 1 °C on a medium containing bile salts (Bile Esculin Azide agar), resulting in blackening of the
medium under the conditions specified in this document
3.3
enumeration of enterococci
determination of the number of colony-forming units (CFU) of enterococci per gram or per millilitre of
product or per sample device, when the analysis and calculation is carried out in accordance with this
document
4 Principle
The initial suspension and/or aliquots of appropriate dilutions are used to inoculate Slanetz-Bartley agar
plates through spread plating, which are incubated at 37 °C for 46 h. After incubation, presumptive
enterococci colonies are enumerated. If the number of presumptive enterococci colonies isolated on
Slanetz-Bartley agar exceeds a limit value, these are confirmed by inoculation on pre-heated plates of Bile
Esculin Azide (BEA) agar, which are incubated at 44 °C for 2 h to detect blackening of the agar medium.
If no blackening occurs, the plates are incubated again at 44 °C for up to 20 h.
5 Culture media and reagents
Follow current laboratory practices in accordance with standards comparable to EN ISO 7218. The
composition of culture media and reagents and their preparation are specified in Annex B. For
performance testing of culture media, it is advised to follow the procedures of EN ISO 11133.
6 Equipment and consumables
Disposable equipment is an acceptable alternative to reusable glassware if it has suitable specifications.
The usual microbiological laboratory equipment (see EN ISO 7218) and, in particular, the following shall
be used.
6.1 Equipment for dry sterilization (oven) and/or wet sterilization (autoclave).
6.2 Incubator(s), capable of maintaining a temperature of 37 °C ± 1 °C, 44 °C ± 1 °C and/or a range of
47 °C to 50 °C.
6.3 Scales, of the required range and accuracy for the different products to be weighed.
6.4 Water bath, capable of maintaining temperatures of 47 °C to 50 °C.
6.5 Cooling unit, adjustable at 5 °C ± 3 °C.
6.6 pH-meter, capable of reading to the nearest 0,1 pH unit at 20 °C to 25 °C.
6.7 Sterile loops, of 10 μl volume (approximate diameter 3 mm) and of 1μl volume, inoculating
needles, inoculating wires.
6.8 Sterile spreaders (hockey-stick type),or spatulas or a spiral plater with a sanitized
dispensing system or disposable one–way micro syringes.
6.9 Sterile membrane filters or sterile stamp pads, to transfer colonies onto the confirmation
medium.
6.10 Sterile tubes, bottles or flasks, with caps and of appropriate capacity.
6.11 Graduated pipettes or automatic pipettes and sterile tips, with wide opening if necessary, of
nominal capacities of 0,1 ml, 1 ml and 10 ml.
6.12 Sterile Petri dishes, with a diameter of approximately 90 mm or a diameter of approximately
140 mm (optional).
6.13 Tweezers.
7 Sampling
Sampling is not part of the method specified in this document. Follow EN 12579 dealing with soil
improvers and growing media. It is important that the laboratory receives a sample that is representative
of the product under consideration. The sample should not have been damaged or changed during
transport or storage.
8 Preparation of the test sample
Prepare the test sample from the laboratory sample in accordance with prEN 13040-2. If there is no
specific International Standard available, it is recommended that the parties concerned come to an
agreement on this subject.
9 Procedure
9.1 General
The procedure as given in Annex A shall be followed.
The time elapsing between the start of the preparation of the initial suspension and the moment when
the plates are inoculated shall not exceed 45 min.
9.2 Preparation of the initial suspension and decimal dilutions
Preparation of the initial suspension and further decimal dilutions shall be performed according to
prEN 13040-2.
Aliquots of the initial suspension should only be used for cultivation if no toxic or inhibiting substances
are expected in the sample. For blended products with high amounts of minerals, it is recommended to
−2
use aliquots from the first dilution (10 ) and higher. Liquid materials may be used undiluted for
cultivation if they do not contain any toxic or inhibiting substances.
9.3 Inoculation and incubation on Slanetz-Bartley agar
Using a sterile pipette or a micropipette (6.11), 0,1 ml of each appropriate dilution shall be transferred
onto (a) Slanetz-Bartley agar plate(s) (B.2).
The plates with the selective media shall be allowed to reach room temperature if they were stored at
5 °C (6.5). If necessary, dry the surface of the plates before use.
If necessary, the inoculation procedure may be repeated with further decimal dilutions, using a new
sterile pipette for each dilution.
Spiral plating may be used following EN ISO 7218 and manufacturer instructions.
For enumeration, one plate per dilution shall be used with at least two successive dilutions. To improve
the reliability of the results, two plates per dilution are recommended.
If only one dilution is used, then two plates of this dilution shall be used to improve reliability of the
results.
For laboratories that do not operate under quality assurance principles, two plates per dilution shall be
used to improve reliability of the results.
Where greater dilutions are made and low counts are expected, the number of inoculated plates for
enumeration tests should be increased to ensure that an inoculation volume corresponding to at least
0,1 g of the test portion is distributed on the plates. If the colony counts expected from the first dilution
−2
are ≤ 10, it is recommended to add 1 ml of the first dilution (10 ) to one Petri dish with a diameter of
140 mm or to use three Petri dishes with a diameter of 90 mm to make the counting result statistically
more stable.
The inoculated Slanetz-Bartley agar plates shall be incubated upside down in an incubator (6.2) set at
37 °C for 46 h ± 2 h.
9.4 Enumeration of colonies
After incubation, all plates (9.3) showing less than 150 typical colonies and less than 300 total (typical
and atypical) colonies shall be used for the enumeration. Atypical colonies shall not be considered for the
enumeration.
Typical formazan-positive enterococci colonies on Slanetz-Bartley agar are dark red, maroon or pink in
colour (either in the centre and surrounded by a narrow colourless zone, or throughout the colony), with
a variation in diameter from 0,3 mm to 2 mm.
Typical colonies on Slanetz-Bartley agar (B.2) are expressed as “presumptive enterococci” (3.1).
If there are no typical colonies on Slanetz-Bartley agar (B.2), the negative result should refer to
“enterococci” (3.2) and not to “presumptive enterococci” (3.1).
9.5 Confirmation
9.5.1 General
If the calculated number of presumptive enterococci (3.1) colonies is above a given limit value (for
example, the limit values given for soil improvers and growing
...
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