Coliform Medium w/ SLS w/ Sterile Membrane Filter

Principle And Interpretation

Field of Application: These are ready to use sterile culture media in the form of a 50 mm biological inert absorbent pads impregnated with standard culture medium, then dried and sterilized in 55 mm petri plate. They eliminate the need of laborious media preparation and autoclaving procedures. The nutrient pads are to be just rewetted with sterile distilled water and are ready for use. Use of nutrient pads allows larger sample volumes to be tested at a time, thereby helping time conservation. Results can be interpreted directly by counting the CFUs, therefore one can quantify the microbial load present in the sample. MF026, HiCrome Coliform Agar w/SLS has chromogenic mixture and Sodium lauryl sulphate (SLS). Sodium lauryl sulphate (SLS) inhibits gram-positive organisms. The enzyme -D-galactosidase produced by coliforms cleaves one chromogen, resulting in purple colouration of coliform colonies. The enzyme -D-glucuronidase produced by Escherichia coli cleaves another chromogen, X-glucuronide. Escherichia coli forms blue coloured colonies due to cleavage of both the chromogens. The addition of L-Tryptophan improves the indole reaction, there by increasing detection reliability in combination with the two chromogens. To confirm Escherichia coli, add a drop of Kovac's reagent on the dark-blue to violet colony. Formation of cherry-red colour indicates the positive reaction.