EN 17707:2024

SLOVENSKI STANDARD
01-februar-2025
Nadomešča:
SIST-TS CEN/TS 17707:2023
Rastlinski biostimulanti - Določanje kvasovk in plesni
Plant biostimulants - Determination of the yeast and mould content
Pflanzen-Biostimulanzien - Bestimmung des Gehalts an Hefen und Schimmelpilzen
Biostimulants des végétaux - Détermination de la teneur en levures et en moisissures
Ta slovenski standard je istoveten z: EN 17707:2024
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 17707
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2024
EUROPÄISCHE NORM
ICS 65.080 Supersedes CEN/TS 17707:2022
English Version
Plant biostimulants - Determination of the yeast and
mould content
Biostimulants des végétaux - Détermination de la Pflanzen-Biostimulanzien - Bestimmung des Gehalts an
teneur en levures et en moisissures Hefen und Schimmelpilzen
This European Standard was approved by CEN on 26 August 2024.

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. 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 European Standard 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, Türkiye 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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17707:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Principles . 7
4.1 General . 7
4.2 Plate count method . 7
5 Diluent and culture media . 8
5.1 General . 8
5.2 Diluent . 8
5.3 Culture media . 8
6 Apparatus and glassware . 8
7 Handling of plant biostimulants and sampling . 8
8 Procedure. 8
8.1 General . 8
8.2 Test portion and initial suspension . 9
8.2.1 General . 9
8.3 Serial dilutions . 9
8.4 Plate count methods . 9
8.4.1 Pour plate method . 9
8.4.2 Surface spread method . 9
8.4.3 Incubation .10
9 Counting of colonies .10
10 Expression of results .10
10.1 Method of calculation .10
10.2 Interpretation .11
11 Test report .12
Annex A (normative) Composition and preparation of culture media and reagents .13
A.1 General .13
A.2 Phosphate buffered saline (PBS) .13
A.3 Sabouraud dextrose chloramphenicol agar medium (SDCA) .14
A.4 Potato dextrose agar (PDA) medium with antibiotics .14
A.5 Glucose-peptone (GP) agar medium with antibiotics .15
A.6 Malt extract agar (MEA) medium with antibiotics .15
Annex B (informative) Interlaboratory study .16
B.1 Materials used in the interlaboratory study .16
B.2 Results of the interlaboratory study . 17
Annex ZA (informative) Relationship of this European Standard and the essential
requirements of Regulation (EU) 2019/1009 making available on the market of EU
fertilising products aimed to be covered . 19
Bibliography . 20
European foreword
This document (EN 17707:2024) has been prepared by Technical Committee CEN/TC 455 “Plant
biostimulants”, 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 May 2025, and conflicting national standards shall be
withdrawn at the latest by May 2025.
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.
This document supersedes CEN/TS 17707:2022.
— the Introduction has been updated and Table 1 has been removed;
— normative references have been updated;
— in Clause 3, new terms and definitions have been added and others have been revised;
— Annexes A, B and C have been revised;
— Annex ZA has been added.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
For the relationship with EU Legislation, see informative Annex ZA, which is an integral part of this
document.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations 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, Türkiye and the United
Kingdom.
Introduction
The European Committee for Standardization (CEN) was requested by the European Commission (EC) to
draft European Standards or European Standardization deliverables to support the implementation of
Regulation (EU) 2019/1009 of 5 June 2019 [1] laying down rules on the making available on the market
of EU fertilising products (“FPR” or “Fertilising Products Regulation”).
This standardization request, presented as SR M/564 and relevant amendments, also contributes to the
Communication on “Innovating for Sustainable Growth: A Bio economy for Europe”. The interest in plant
biostimulants has increased significantly in Europe as a valuable tool to use in agriculture.
Standardization was identified as having an important role in order to promote the use of biostimulants.
The work of CEN/TC 455 seeks to improve the reliability of the supply chain, thereby improving the
confidence of farmers, industry, and consumers in biostimulants, and will promote and support
commercialisation of the European biostimulant industry.
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices and to ensure compliance
with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document be
carried out by suitably trained staff.
1 Scope
This document specifies a horizontal method for the enumeration of yeasts and moulds present in plant
biostimulants intended for use in agriculture, by means of the colony count technique after aerobic
incubation at 25 °C ± 2,5 °C.
This document allows the enumeration of yeasts and moulds, in technical and formulated plant
biostimulants, both in liquid and solid states. The method is applicable to microbial plant biostimulants
except those composed of fungi or yeasts.
If necessary, yeasts and moulds enumerated can be identified using suitable identification tests.
This document is applicable to the blends of fertilizing products where a blend is a mix of at least two of
the following component EU fertilising products categories: Fertilizers, Liming Materials, Soil Improvers,
Growing Media, Plant Biostimulants, and where the following category Plant Biostimulants is the highest
% in the blend by mass or volume, or in the case of liquid form by dry mass. If Plant Biostimulants is not
the highest % in the blend, the European Standard for the highest % of the blend applies. In case a blend
of fertilizing products is composed of components in equal quantity or in case the component EU
fertilising products used for the blend have identical formulations , the user decides which standard to
apply.
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 17702-1:2024, Plant biostimulants — Sampling and sample preparation — Part 1: Sampling
EN 17708:2024, Plant biostimulants — Preparation of sample for microbial analysis
EN 17714:2024, Plant biostimulants — Determination of microorganisms’ concentration
EN 17724:2024, Plant biostimulants — Terminology
3 Terms and definitions
For the purposes of this document, the terms and definition given in EN 17724:2024 and the following
apply.
ISO and IEC maintain terminological 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
yeast
mesophilic aerobic microorganism which, using mycological agar medium under the conditions
described in this document, develops matt or shiny round colonies (3.3) on the surface of the medium,
usually having a regular outline and a more or less convex surface

An example of such a blend is a product with 2 claimed functions consisting of a non-microbial plant biostimulant
and an organic fertilizer composed of 1kg/kg of plant biostimulant from seaweed.
3.2
mould
mesophilic aerobic filamentous microorganism which, on the surface of mycological agar medium under
the conditions described in this document, usually develops flat or fluffy spreading colonies (3.3) often
producing spores or conidia
3.3
colony
localized visible accumulation of microbial mass (such as prokaryotes, bacteria, micromycetes, yeasts and
fungi) or organisms (such as Dreissena species) developed on or in a solid nutrient medium from a viable
particle or organism
Note 1 to entry: Frequently, microcolonies from nearby viable particles, before becoming visible, fuse into one
macrocolony. The number of visible colonies is, therefore, usually an underestimate of the number of viable
particles.
[SOURCE: ISO 6107:2021, 3.119 [2]]
3.4
product
portion of an identified plant biostimulant received in the laboratory for testing
3.5
sample
portion of the product (3.4) that is used in the test to prepare the initial suspension
3.6
initial suspension
suspension (or solution) of the sample (3.5) in a defined volume of an appropriate diluent
3.7
sample dilution
dilution of the initial suspension (3.6)
4 Principles
4.1 General
This method shall be followed for the enumeration of colonies on a selective agar medium.
4.2 Plate count method
The plate count consists in the following steps:
— preparation of poured plates, or spread plates using a specific culture medium. Depending on the
expected number of colonies, a specified quantity of the sample (if the product is liquid), or of an
initial suspension (in the case of other products), or decimal dilutions of the sample/suspension shall
be inoculated;
— aerobic incubation of the plates shall be 25 °C ± 2,5 °C for 3 days to 5 days;
— calculation of the number of colony-forming units (CFU) of yeasts and moulds per gram or per
millilitre of sample from the number of colonies obtained on plates chosen at dilution levels
producing countable colonies. Moulds and yeasts may be counted separately, if necessary.
NOTE An alternative condition for incubation may be 22,5 °C ± 2,5 °C, for 5 days to 7 days, using the culture
medium without antibiotic. If necessary, to distinguish yeast colonies from bacterial colonies, the identity of any
doubtful colonies is confirmed by examination with a binocular magnifier or microscope.
5 Diluent and culture media
5.1 General
The following diluents and culture media should be used since they are suitable for the enumeration of
yeasts and moulds. Other diluents and culture media may be used if they have been demonstrated to be
suitable for use.
Diluent and culture media should be prepared using the descriptions provided in this document or from
dehydrated culture media, according to the instructions from the manufacturer.
NOTE Ready-to-use media may be used when their composition and/or growth yields are comparable to those
of the formulae given in the present document.
5.2 Diluent
In the preparation of the initial suspension and further decimal dilutions, the Phosphate Buffer Solution
(PBS) should be used, and the recipe described in A.2 shall be followed. Another suitable diluent (e.g.
Buffered Peptone Water) may be used. The preparation of this alternative diluent is not part of the
method specified in this document: EN 17708:2024 shall be used.
5.3 Culture media
See Annex A for the list and recipes of the possible media to be used in the inoculation by plating
technique of the initial suspension and the further decimal dilutions.
6 Apparatus and glassware
Use the laboratory equipment, apparatus and glassware typical of microbiological laboratory. See
EN 17708:2024 for a detailed list.
7 Handling of plant biostimulants and sampling
It is important that the laboratory receives a sample which is truly representative and has not been
damaged or changed during transport or storage.
Sampling is not part of the method specified in this document: EN 17702-1:2024 shall be used.
If necessary, the product to be tested may be equilibrated at room temperature before starting the
analysis.
8 Procedure
8.1 General
Use sterile material, equipment and aseptic techniques to prepare the sample, initial suspension and
dilutions. In the case of the preparation of the initial suspension, the time that elapses between the end
of the preparation and the moment the inoculum comes into contact with the culture medium shall not
exceed 45 min, unless specifically mentioned in the established protocols or documents.
Appropriate negative controls (diluent-only) should be run concurrently with the sample serial dilutions.
This step can be performed by incubating an aliquot of the diluent (i.e. 9 ml) at the same conditions of the
test to verify the absence of turbidity to assess the sterility of the diluent. Or, alternatively, 1 ml of the
diluent may be spread over a surface of the same agar medium used in the analysis. The plate shall be
incubated in the same conditions of the test to verify the absence of growth to assess the sterility of the
diluent.
8.2 Test portion and initial suspension
8.2.1 General
The preparation of the initial suspension is not part of the method specified in this document:
EN 17708:2024 shall be used.
In the preparation of the initial suspension, the Phosphate Buffer Solution (PBS) should be used. Another
suitable diluent (e.g. Buffered Peptone Water) may be used (see 5.2).
8.3 Serial dilutions
Additional serial dilutions (e.g. 1:10 dilution) may be performed from the initial suspension using the
same diluent (according to the expected level of contamination of the product). Mix the dilutions in order
to avoid sedimentation of microorganism-containing particles.
EN 17708:2024 shall be used for the preparation of the decimal dilutions.
8.4 Plate count methods
8.4.1 Pour plate method
In Petri dishes from 85 mm to 100 mm in diameter add, using a sterile pipette, 1 ml of the initial
suspension and/or sample dilutions and pour 15 ml to 20 ml of the melted agar medium kept in a water
bath at no more than 48 °C.
For liquid products, it is possible to also inoculate 1 ml of undiluted product.
Mix the sample with the medium carefully rotating or tilting the plates. Allow the mixture in the Petri
dishes to solidify on a horizontal surface at room tempe
...