Lauryl Sulfate Broth (NutriSelect® Basic) is formulated to provide rapid growth of coliforms while suppressing interfering non-coliform organisms. The selectivity is achieved by the inclusion of sodium lauryl sulfate, which inhibits the growth of most Gram-positive bacteria and many Gram-negative bacteria other than coliforms. Tryptose provides the essential nitrogen and carbon sources, while lactose serves as the fermentable carbohydrate. The production of gas, trapped in an inverted Durham tube, indicates a positive presumptive test for coliforms. As part of the NutriSelect® Basic line, this medium offers a reliable and cost-effective solution for routine microbiological analysis.
Advantages
- High Sensitivity: Optimized nutrient balance ensures the recovery of even slow-growing or "stressed" coliform strains.
- Standardized Methodology: Complies with the formulations recommended by APHA, AOAC, and EPA for water and food testing.
- Presumptive Accuracy: Effectively eliminates false positives caused by anaerobic gas-formers like Clostridium species.
- NutriSelect® Basic Quality: Provides consistent performance for high-volume routine testing in industrial and environmental labs.
- Clear Interpretation: Vigorous gas production and increased turbidity facilitate easy reading of results.
Interpretation of Results
| Microorganism |
Growth |
Gas Production |
| Escherichia coli |
Luxuriant |
Positive (+) |
| Enterobacter aerogenes |
Luxuriant |
Positive (+) |
| Staphylococcus aureus |
Inhibited |
Negative (-) |
| Enterococcus faecalis |
Inhibited |
Negative (-) |
Technical specifications
| Catalogue number |
61749 |
| Brand / Product Line |
Sigma-Aldrich / NutriSelect® Basic |
| Typical Composition (g/L) |
Tryptose (20.0); Lactose (5.0); NaCl (5.0); Dipotassium phosphate (2.75); Monopotassium phosphate (2.75); Sodium lauryl sulfate (0.1) |
| pH (at 25 °C) |
6.8 ± 0.2 |
| Preparation |
35.61 g/L |
| Storage Temperature |
15 – 25 °C |
Available packaging options
| 61749-500G |
500 g plastic bottle |
