Recomendação ERSAR (IRAR) nº. 5/2005
Alternative method for Coliform bacteria and Escherichia
coli analysis
“The presence and extent of faecal pollution is an important factor in assessing the quality of a body of
water and risk to human health from infection. Examination of water samples for the presence of
Escherichia coli, which normally inhabits the bowel of man and other warm-blooded animals, provides an
indication of such pollution. Examination of coliform bacteria can be more difficult to interpret because
some coliform bacteria live in soil and surface fresh water, and are not always intestinal. Therefore, the
presence of coliform bacteria, although not proof of feacal contamination, may indicate failure in treatment
or distribution. The identification of the strains isolated can sometimes provide an indication of their origin.
Filtrar 100 mL da amostra de Água, ou as suas diluições, com filtro em
MCE de 0,45 µm e 47 mm ∅ (ref. 1080200), e transferir o filtro para
placa de meio Membrane Lauryl Sulfate Agar
Incubar a 36±2ºC/21±3h
Contar colónias características (produção de cor amarela nas colónias
ou meio_ Bactérias Lactose positiva).
Isolar colónias características em meio não seletivo, YEA (ref. 611016;
412120) e incubar a 36±2ºC/21±2h
Teste Indol e Fluorescência:
Selecionar cerca de 5 colónias
Inocular em meio DEVFluorocult. Incubar a
44±0,5ºC/21±3h e adicionar
reagente de Kovacs (ref.
80271
Teste Oxidase: Selecionar
cerca de 5 colónias Inocular e
fazer teste de oxidase (ref.
88029)
Contar todas as colónias oxidase negativa
Bactérias Coliformes
Contar todas as colónias oxidase negativa, Fluorescência e indol
positivo
E. coli