For isolation and enumeration of Enterococci in sewage, water and foods by membrane filter technique
M-Enterococcus Agar Base is used for the isolation and enumeration of Enterococci in sewage, water and food by membrane filter technique. The presence of enterococci is a valuable bacterial indicator for determining the extend of fecal contamination of recreational surface waters.3 m-Enterococcus Agar is recommended for the detection of fecal streptococci using the membrane filtration technique for water testing. The food industry also has applications for testing enterococci using m-Enterococcus Agar. Slanetz and Bartley modified this medium by the addition of Triphenyl Tetrazolium Chloride (TTC). They observed that larger colonies and higher counts were obtained by placing membrane filters directly on the agar surface than on pads saturated with liquid medium. To increase the sensitivity, polysorbate 80 (0.5 ml/l) and sodium carbonate (2 ml of a 10% aqueous solution per litre) is added. Casein enzymic hydrolysate, papaic digest of soyabean meal, yeast extract, dextrose act as source of carbon, nitrogen and other essential growth nutrients. Dipotassium Phosphate acts as a buffer. Sodium azide is used to inhibit gram negative organisms. TTC is a rapid indicator of bacterial growth. TTC is reduced to insoluble formazan inside the bacterial cells, which gives red coloration to colonies. For filtration, transfer the filter aseptically to agar medium, avoiding any air bubbles beneath the membrane. It can also be used by streaking the specimen and incubating the plates at 35 ± 2°C for 24-48 hours. After incubation, count all pink to dark red colonies as Enterococci.