THE AC/TC BACTERIAL RATIO: A TOOL FOR WATERSHED QUALITY MANAGEMENT

An inexpensive tool for indicating microbial quality in watersheds is presented that utilizes the conventional total coliform test, comparing the relative concentrations of different colonies that form on a membrane filter fed by m-Endo media. These bacterial colonies can be classified into 3 types;...

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Bibliographic Details
Published in:Journal of Water and Environment Technology 2005, Vol.3(2), pp.271-277
Main Author: Brion, Gail Montgomery
Format: Article
Language:English
Subjects:
atypicals
indicators
runoff
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Summary:An inexpensive tool for indicating microbial quality in watersheds is presented that utilizes the conventional total coliform test, comparing the relative concentrations of different colonies that form on a membrane filter fed by m-Endo media. These bacterial colonies can be classified into 3 types; typical (TC), atypical (AC), and background. The ratio of the concentrations of AC colonies to those of TC is related to water quality, fecal loadings, and fecal age. The AC/TC ratio relies upon shifts in populations between indigenous and introduced bacteria, with the indigenous bacteria providing a baseline against which the concentrations of the introduced are evaluated. When the AC/TC ratio is low (20) and can be related to healthier water quality conditions. Different types of runoff have different AC/TC values with human sewage at the lowest end of the spectrum with a value of 1.5 under normal conditions.
ISSN:1348-2165
1348-2165
DOI:10.2965/jwet.2005.271