Selective Growth Media for Differentiation and Detection of Escherichia coli and Other Coliforms
E. coli and other coliforms are important indicator organisms for the presence of pathogens in food, occupational, and environmental safety applications, some of the most important areas of analytical microbiology.
E. coli: Indicator Organism for Fecal Contamination
Normal constituents of the intestinal flora of animals, coliforms are rod-shaped, Gram-negative, non-spore forming facultative anaerobes. They ferment lactose with the production of acid and gas when incubated at 35–37 °C. Although commonly found in lakes, rivers, swimming pools, and soil from faecal sources, in most cases coliforms do not cause illness. However, they are used as indicators for other pathogenic organisms of faecal origin. The most common genera of coliforms are Citrobacter, Enterobacter, Escherichia, Klebsiella, and Serratia.
Escherichia coli (Figure 1) is the best-known coliform and an important indicator of faecal contamination because it is found almost exclusively in faeces. Occasional outbreaks of food poisoning have been linked to certain gastroenteritis-causing E. coli strains, such as serotype O157:H7. E coli are rod-shaped bacteria, distinguished from most other coliforms by their ability to ferment lactose at 44 °C, and by their growth characteristics on certain media. Easy to culture, E. coli is often used in molecular biology.

Figure 1.Escherichia coli
Selective Growth Media for E. coli
Microbiological media is used not only to grow microorganisms, but also to select or identify a particular type of microorganism based on some unique or distinctive aspect of its biochemistry. Most of this so-called “selective growth” media contain a protein source, often a hydrolysate of casein, and a fermentable sugar, like lactose or glucose. Occasionally an indicator, like neutral red or bromo cresol purple, is added to detect the acid produced by the fermentation process.
A new generation of selective media is available from us that employs chromogenic and fluorogenic substrates (Figure 2). These media indicate E. coli by the presence of β-D-glucuronidase (GUD) and other coliforms by the presence of β-D-galactosidase. GUD catalyses the hydrolysis of β-D-glucopyranosiduronic acid into the corresponding aglycones and D-glucuronic acid. GUD is present in 94–96% of E. coli strains, but is also found in some Salmonella, Shigella and Yersinia spp. (1-3). There is a wide range of media available that use different substrates for the detection of E. coli and coliforms (Table 1). The media are also supplemented with agents like bile salts, brilliant green, sodium lauryl sulphate, and other substances to enhance their selectivity.

Figure 2.HiCrome™ M-TEC Agar for differentiation and enumeration of thermotolerant E.coli from water by membrane filtration technique. E.coli colonies appear blue because the chromogen, X-glucuronide, is cleaved by the enzyme β-glucuronidase.
Media System | Product No. | Name |
---|---|---|
Non-selective media used for identification | A0715 | Andrade Peptone Water |
28943 | Andrade peptone water, Vegitone | |
70133 | Blood Agar (Base) | |
36408 | Bromcresol Purple Broth | |
22520 | China Blue Lactose Agar | |
27048 | Christensen’s Urea Agar | |
55420 | CLED Agar | |
D2935 | Decarboxylase Broth Base, Moeller | |
31436 | DEV Lactose Broth | |
31437 | DEV Lactose Peptone Broth | |
31406 | DEV Tryptophan Broth | |
16447 | Glucose Bromcresol Purple Agar | |
73009 | HiCrome™ ECC Agar | |
00563 | HiCrome™ MM Agar | |
16636 | HiCrome™ UTI Agar, modified | |
60787 | Kligler Agar | |
94792 | Lactose Broth | |
70142 | Lactose Broth | |
19057 | Lactose Broth, Vegitone | |
62915 | Lysine Iron Agar | |
M8802 | Malonate Broth | |
39484 | Methyl Red Voges Proskauer Broth | |
69150 | Methyl Red Voges Proskauer Saline Broth | |
17171 | Mineral-modified Glutamate Broth (Base) | |
M1053 | Motility Test Medium | |
17178 | Mucate Broth | |
17165 | MUG Tryptone Soya Agar | |
72548 | Nitrate Broth | |
75315 | OF Test Nutrient Agar | |
51413 | Plate Count MUG Agar | |
85463 | Simmons Citrate Agar | |
44940 | Triple Sugar Iron Agar | |
93657 | Tryptone Medium | |
07507 | Tryptone Water | |
39964 | Tryptone Water, Vegitone | |
51463 | Urea Broth | |
Selective media for differentiation | 16016 | BRILA MUG Broth |
31432 | DEV ENDO Agar | |
44657 | ECD MUG Agar | |
70186 | EMB Agar | |
E5399 | Endo Agar | |
70137 | ENDO Agar (Base) | |
48716 | Gassner Agar | |
81938 | HiCrome™ Coliform Agar | |
70722 | HiCrome™ E. coli Agar B | |
85927 | HiCrome™ ECC Selective Agar | |
09142 | HiCrome™ ECD Agar with MUG | |
Selective media for differentiation | 83339 | HiCrome™ Mac Conkey Sorbitol Agar |
90924 | HiCrome™ M-TEC Agar | |
51489 | HiCrome™ Rapid Coliform Broth | |
54232 | Lactose TTC Agar with Tergitol®-7 | |
62087 | Levine EMB Agar | |
62634 | LST-MUG Broth | |
70143 | Mac Conkey Agar No. 1 | |
19352 | Mac Conkey Agar No. 1, Vegitone | |
94216 | MacConkey Agar with Crystal Violet, Sodium Chloride and 0.15 % Bile Salts | |
M8302 | MacConkey Agar with Crystal Violet, Sodium Chloride and 0.15 % Bile Salts | |
70144 | MacConkey Broth | |
75717 | MacConkey Broth purple | |
16377 | MacConkey Broth purple | |
63014 | MacConkey MUG Agar | |
51405 | MacConkey-Agar (without salt) | |
88902 | MacConkey-Sorbitol Agar | |
39734 | Membrane Lactose Glucuronide Agar | |
85766 | m-Endo Agar LES | |
96961 | M-FC Agar | |
19958 | m-FC Agar Plates (55 mm diameter) | |
43291 | M-FC Agar, Vegitone | |
07348 | M-Lauryl Sulphate Broth | |
M1678 | MUG EC Broth | |
92435 | TBX Agar | |
86455 | Tergitol®-7 Agar | |
70188 | Violet Red Bile Agar | |
42376 | Violet Red Bile Agar, Vegitone | |
79873 | Violet Red Bile Glucose Agar | |
70189 | Violet Red Bile Glucose Agar | |
17213 | Violet Red Bile Glucose Agar without Lactose | |
53605 | Violet Red Bile Glucose Agar without Lactose, Vegitone | |
41270 | Violet Red Bile Lactose Dextrose Agar | |
95273 | VRB MUG Agar | |
17215 | WL Differential Agar | |
76721 | XLT4 Agar (Base) | |
Selective media | 17112 | A1 Broth |
16025 | Brilliant Green Bile Lactose Broth | |
44653 | EC Broth | |
44655 | ECD Agar | |
61749 | Lauryl sulphate Broth | |
17349 | Lauryl sulphate Broth | |
17162 | M Endo Broth | |
17184 | M HD Endo Broth with Brilliant Green | |
49522 | M-Lauryl Sulphate Broth, Vegitone | |
69965 | Mossel Broth |
References
To continue reading please sign in or create an account.
Don't Have An Account?