1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-20605-5 SANS 5553:2008Edition 2SOUTH AFRICAN NATIONAL STANDARD Media and reagents for microbiological tests Published by Standards South A
4、frica 1 dr lategan road groenkloof private bag x191 pretoria 0001 tel: 012 428 7911 fax: 012 344 1568 international code + 27 12 www.stansa.co.za Standards South Africa SANS 5553:2008 Edition 2 Table of changes Change No. Date Scope Foreword This South African standard was approved by National Commi
5、ttee StanSA TC 5140.26, Microbiological evaluation of foods, feeds and beverages, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. This document was published in February 2008. This document supersedes SABS SM 553:1975 (first edition). SAN
6、S 5553:2008 Edition 2 1 Contents Page Foreword 1 Scope . 3 2 Normative references 3 3 Apparatus . 3 4 Quality of ingredients 3 5 Accuracy of measurements 4 6 General procedure for the preparation of media. 4 7 Preparation of reagents 5 SANS 5553:2008 Edition 2 2 This page is intentionally left blank
7、 SABS 5553:2008 Edition 2 3 Media and reagents for microbiological tests 1 Scope This standard specifies the quality of ingredients and the general method to be used in the preparation of media and reagents for microbiological tests in which the use of different formulations and ingredients might in
8、fluence the results of the test. Standard chemicals for which current chemical grading is used or for which no special requirements for microbiological applications are needed are not covered. 2 Normative references The following referenced documents are indispensable for the application of this doc
9、ument. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. Information on currently valid national and international standards can be obtained from Standards South Africa. SANS 171, Glassware
10、and equipment for microbiological tests. SANS 3696, Water for analytical laboratory use Specification and test methods. 3 Apparatus The apparatus and equipment used shall comply with the requirements of SANS 171. 4 Quality of ingredients 4.1 Water All water shall comply with the requirements of grad
11、e 2 water as given in SANS 3696. 4.2 Other ingredients Use only ingredients of quality acceptable for microbiological purposes in the preparation of the media and reagents. If doubt exists regarding the suitability of any material, it should be replaced or special tests should be carried out to conf
12、irm its quality. SANS 5553:2008 Edition 2 4 5 Accuracy of measurements Except where otherwise directed, the following tolerances shall apply: a) on temperatures . 2 C b) on masses 1,0 % c) on volumes . 1,0 % d) on periods of time 1,0 % e) on pH values 0,1 pH unit 6 General procedure for the preparat
13、ion of media NOTE Many of the media required are obtainable in dehydrated form. If these are used, the manufacturers instructions regarding their reconstitution and sterilization should be carefully followed. 6.1 General Unless otherwise specified: a) all masses are in grams and the quantities presc
14、ribed are sufficient for the preparation of 1 L medium in each case; b) all salts are anhydrous; and c) beef extract, meat extract, and yeast extract are specified in paste form. If dehydrated extracts are used, quantities should be changed in accordance with the manufacturers instructions. 6.2 Proc
15、edure 6.2.1 Dissolving of ingredients Dissolve the ingredients listed in about 800 mL of water by heating slowly and stirring constantly (boil the suspension if necessary). Mix the solution thoroughly, allow it to cool to about 60 C, and then so adjust the pH value (as in 6.2.2) that it will be at t
16、he specified level after the medium has been diluted to its final volume, filtered, dispensed, and sterilized. This usually means that the pH value of the medium before sterilization will have to be 0,1 pH unit to 0,2 pH unit higher than the required value, because some ingredients, notably peptone,
17、 will release acid on heating. Add water to bring the solution to a volume of 1 L. 6.2.2 Adjustment of pH value of media Unless otherwise directed, use a 1 M solution of hydrochloric acid or of sodium hydroxide, as appropriate, and add it dropwise while the medium is constantly stirred and its pH va
18、lue constantly observed, until the specified pH value (measured at 25 C) is obtained. 6.2.3 Filtration of media Whenever it is necessary to filter a medium in the course of its preparation, proceed as follows: a) Filter a medium that does not contain a solidifying agent, i.e. a liquid medium or brot
19、h, through a medium speed filter paper; and SABS 5553:2008 Edition 2 5 b) If the medium contains a solidifying agent (e.g. agar), filter it through a 10 mm to 15 mm thick layer of pre-wetted absorbent cotton wool. To prevent solidification of the medium during filtration, use a steam-jacketed funnel
20、. Alternatively, carry out the filtration in a steam chamber. 6.2.4 Dispensing 6.2.4.1 Liquid media Dispense 10 mL portions of the medium into suitable sterile bottles fitted with screw caps that can be autoclaved and of capacity 30 mL, or into suitably stoppered test tubes. Stir the medium constant
21、ly while dispensing. Sterilize (see 6.2.5). 6.2.4.2 Solid media for the preparation of plates Dispense 15 mL portions of the medium into suitable sterile bottles fitted with screw caps that can be autoclaved and of capacity 30 mL, or into suitably stoppered test tubes. Stir the medium constantly whi
22、le dispensing. Sterilize (see 6.2.5). 6.2.4.3 Solid media for the preparation of slopes Dispense 10 mL portions of the medium into suitable sterile bottles fitted with screw caps that can be autoclaved and of capacity 30 mL, or into suitably stoppered test tubes. Stir the medium constantly while dis
23、pensing. Sterilize (see 6.2.5). Immediately after sterilization and while the medium is still melted, lay the bottles (or when relevant, the test tubes) on a 1 in 4 sloped surface and let the agar set. 6.2.5 Sterilization When sterilization by autoclaving is specified and unless otherwise directed,
24、autoclave the medium at (03120+) C for 15 min. 6.3 Control of prepared media Ensure by suitable incubation tests that prepared media are sterile and are capable of supporting the growth of the relevant organisms under the stated conditions of incubation. 6.4 Storage Ensure that prepared media are ca
25、refully protected from exposure to heat and sunlight and have not evaporated or changed in concentration or pH value. Unless otherwise specified, media shall be used up within three months of preparation. 7 Preparation of reagents 7.1 Prepare each reagent exactly as specified and prepare only suffic
26、ient at one time for three months use. 7.2 Store the reagent in bulk in a reagent bottle that is labelled with the name of the reagent, the date prepared, the expiry date and the name of the person that prepared the reagent in a cool dark place. SANS 5553:2008 Edition 2 6 7.3 Keep only a small volum
27、e available for actual use in a well labelled dispensing bottle. 7.4 Never mix old with freshly prepared reagent. Always carefully clean and dry all reagent bottles before refilling. 7.5 Before (or during) each test or series of tests, check each reagent for positive and negative reaction. 7.6 Keep a record of the date of preparation of each quantity of reagent and discard any reagent when results obtained with it are doubtful. Standards South Africa
