9221 MULTIPLE-TUBE FERMENTATION ... - Edge Analytical

9221 MULTIPLE-TUBE FERMENTATION TECHNIQUE FOR MEMBERS OF THECOLIFORM GROUP*9221 A. IntroductionThe coliform group consists of several genera of bacteriabelonging to the family Enterobacteriaceae. The historical defi-nition of this group has been based on the method used fordetection, lactose FERMENTATION , rather than on the tenets ofsystematic bacteriology. Accordingly, when the fermentationtechnique is used, this group is defined as all facultative anaer-obic, gram-negative, non-spore-forming, rod-shaped bacteriathat ferment lactose with gas and acid formation within 48 h at35 standard test for the coliform group may be carried out bythe MULTIPLE-TUBE FERMENTATION technique or presence absenceprocedure (through the presumptive-confirmed phases or com-pleted test) described herein, the membrane filter (MF) technique(Section 9222) or the enzymatic substrate coliform test (Section9223).

ining drinking water via the fermentation technique, process all tubes or bottles demonstrating growth, with or without a positive acid or gas reaction, to the confirmed phase (9221B.3). Drinking water samples that are positive for total coliforms also must be tested for thermotolerant (fecal) coliforms (9221E) or Esche-richia coli (9221F).

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