PROGRAMS & PLANS - Analytical Methods: Bacteriology-agar media for determining coliform bacteria

                                           July 18, 1972

QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM N0. 73.01

Subject: PROGRAMS & PLANS - Analytical Methods: Bacteriology-
         agar media for determining coliform bacteria

The WRD has had a continuing history of difficulty in 
identifying total and fecal coliform colonies when using 
Millipore ampouled media with the membrane filter technique 
(see QW Branch Technical Memoranda 70.05 and 71.07). The Task 
Group on Biology and Microbiology arranged for parallel test 
sets of total coliform and fecal coliform determinations 
using recently purchased Millipore ampoules and freshly 
prepared agar media. The results of those tests were 
transmitted to the Quality of Water Branch in March, 1972. 
Attached is Research Note No. 116 summarizing the results.

Because of the conclusive superiority of freshly prepared 
agar media over commercially prepared media ampoules, it is 
now required that all total coliform and fecal coliform 
determinations by the membrane filter method be performed 
with freshly prepared agar or broth media. Supplies of 
Millipore media ampoules should not be replenished.

Bacteriological media kits with instructions for preparation 
are now being supplied by the Hydrobiological Laboratory in 
St. Louis. A description of the kits was included in WRD 
Memorandum No. 72.149. Information on these media kits can be 
obtained from Mr. Sanford C. Downs, laboratory supervisor. 
Other questions should be directed to this office.



                     R. J. Pickering 
                     Chief, Quality of Water Branch

Attachment

WRD Distribution:
A, B, S, FO, P0