Membrane Lactose Glucoronide Agar (MLGA)

Detect, enumerate and differentiate Escherichia coli and other coliforms by single membrane filtration with Thermo Scientific™ Oxoid™ Membrane Lactose Glucuronide Agar (MLGA) (Dehydrated). The presence of lauryl sulphate and lactose with phenol red allow the selective isolation and differentiation of Escherichia coli and coliforms respectively.

Tests for Escherichia coli and coliforms provide a sensitive means for detection of fecal contamination of drinking water. They are regarded as the most important routine microbial examinations for assessing the effectiveness of water treatment and disinfection and for monitoring water quality in distribution¹. Membrane Lactose Glucuronide Agar (MLGA) supports water testing utilising single membrane filtration.

• Isolate coliforms effectively with MLGA using a single membrane filtration method.
• Lauryl sulphate selects for coliforms by inhibiting Gram-positive organisms.
• Reduced confirmatory tests for E. coli due to the specificity of the reactions in the medium.
• Easy interpretation of the test results due to addition of chromogenic BCIG (5-bromo-4-chloro-3-indolyl-ß-D-glucuronide), E. coli appear as green colonies while other coliform bacteria form yellow colonies.

Identification of Escherichia coli and coliforms is facilitated through two biochemical reactions within the medium: Lactose fermentation is detected by the dye phenol red which gives yellow colonies when acid is produced. The chromogenic substrate BCIG is cleaved by the enzyme glucuronidase and produces a blue chromophore which builds up in the bacterial cells. Coliforms are lactose-positive so colonies will be yellow; Escherichia coli is both lactose-positive and possesses glucuronidase so will appear as green colonies.¹ Strains of E. coli that fail to produce typical colonies on MLGA might produce lower concentrations of the enzyme β-D-glucuronidase.²

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Remel™ and Oxoid™ products are now part of the Thermo Scientific™ brand.