BS EN ISO 7899-2-2000 Water quality一 Detection and enumeration of intestinal enterococci – Part 2: Membrane filtration method.
3 Terms and debriltions
For the prirposes of the pail of ISO 7899. the terms and detentions given In ISGIEC GuIde 2 and Sw following
3.1 inteshnal enterococci
bacteria WhiCh are able to ree 2.3.5nphenltetrazo4h.en chtonde to loima.zan and to lly&otyse at 44 ‘C on the media (63.1 and 6.32) specSwd in lispn of ISO 7899
NOTE See o WVIx A.
4 PrincIple
4.1 FIltration, Incubation arid enumeratIon
The numeration of neetanal eriterococci is based on filtration of a specified volume of water sample ltwough a membrane f*er with a pare size (0.45 itmi siticent to retarl the bacteria. The Idler is placed on a aced selective machum conteining sodium abde (to suppress the grown of Gram negative bacteria) and 23 5•l nltevazoiturn chIdrIde, a colourless th is rejced to red lormazari by Intestinal .nterococci,
Tpcal coloives are red, sith a red. maroon or pint oolow, either In the centre of the colony or throuout.
4.2 ConfirmatIon
It Iplcal colonies are observed, a contematon cop is neeaary. by transfar of Sw membrane, watt d the colonies, onto bileaeeci.i-azide agar, ehea1ed at 44 ‘C. kiesnal entarococo hydrofyse aesilin art tile medium m 2 Ii. The end-product. 6,7dlhydroxycimain. combnes w(h iron(III) lore to give a tan-coloured to black compound which diffuses rio the medium.
5 Apparatus
Except tow dlsposshle glassware which is delivered stenle, glassware shal be slenized In accordance w4fl
Usual microbiological laboratory ec)upnlent arid pawtculnly
5.1 Uembrane filtration apparatus according to ISO 8199
5.2 SterIle membrane fitters, wvtfl a nominal pore size of 0,45 Ij
The ctuality of membrane ters may vwy horn brand to brand or even from belch to batch It is therefore advisable to check the quly on a regtiar basis, m accordance wdfl ISO 7704.
5.3 Incub(o,, capshle of being maintained at 36 C ±2 C.
5.4 Incubetor. caple of being maintained 5144 ‘C * 0.5 C.
5.5 Autoclave. capable of being maintained at 121 ‘C ±3 C.
5.6 SterIle forceps.
5.7 Hotplate or wst.r bath, maintained at 100 ‘CBS EN ISO 7899-2 pdf download.