A 1 Medium

EMD Cat. No. 1.00415.0500
500 g


Selective culture medium for the detection of faecal coliforms in water.

The medium conforms with the recommendations of standard methods ( US-EPA ) for the examination of water.
Typical Composition (g/liter) Quality Control Literature

Mode of Action
 Peptone from casein, lactose and salicin are nutrients and guarantee good growth of micro-organisms. Sodium chloride provides the osmotic balance. Triton™ X 100 is contained as a detergent.
Typical Composition (g/liter)
 Peptone from casein 20.0; lactose 5.0; sodium chloride 5.0; salicin 0.5; Triton™ X 100  1.0 ml
Preparation
 Suspend 31.5 g in 1 liter purified water and fill into tubes containing inverted fermentation vials (Durham-tubes). Autoclave for 10 min. at 121°C
pH : 6.9 ± 0.2 at 25°C
 The prepared medium is clear to slightly opalescent and yellowish in color. The prepared medium can be stored for up to 1 week at room temperature (store in the dark).
 For the examination of 10 ml water samples a double-strength concentrated broth is used.
Experimental Procedure
1. Inoculate tubes according to the Standard Methods MPN-Method.
 2. Incubate for 3 hours at 35 ± 0.5 °C and then continue incubation in a water bath at 44.5 ± 0.2 °C for 21 ± 2 hours.
The water level in the bath must be above the level of the liquid in the test tubes!!!
Evaluation
Gas formation in the Durham tubes indicates the presence of faecal coliforms.
 The number of faecal coliforms is determined using the MPN-table.
Quality control
Test strains
 Inoculum
 approx. CFU
 		Growth
 		Gas formation




Escherichia coli ATCC 25922
 		100
 		Good
 		+
Escherichia coli ATCC 8739
 		100
 		Good
 		+
Enterococcus faecalis ATCC 19433
 		100
 		None / medium
 		None
Enterobacter aerogenes ATCC 13048
 		100
 		Medium / good
 		+/-
Bacillus subtilis ATCC 6633
 		100
 		None
 		None

Literature
Andews, W. H., Pressnell, M. W. 1972. Rapid Recovery of Escherischia coli from estuarine water. Appl. Microbiol. 23:521-523.
 Andrews, W. H., Diggs, C. D., and Wilson,C. R. 1975. Evaluation of a medium for the rapid recovery of Escherischia coli from shellfish. Appl. Mikrobiol. 29: 130-131.
 Standridge and Delfino. 1981. Appl. Environ. Microbiol. 42: 918
 Eaton, A. D., Clesceri, L. S. and Greenberg, A. E. (ed.). 1995. Standard methods for the examination of water and wastewater, 19th. Ed. APHA, Washington D.C.
 Vanderzant, C., and Splittstoesser, D. F. (ed.). 1992. Compendium of methods for the microbiological examination of food, 3rd ed. APHA Washington D.C.
 Association of Official Analytical Chemists. 1995. Bacteriological analytical manual, 8th ed. AOAC International, Gaithersburg, MD