Liofilchem® Nitrate Broth for microbiology

Differentiation of Aerobic and Facultative Anaerobic Gram-Negative Bacteria via the Nitrate Reduction Test

Liofilchem® Nitrate Broth is a selective differential medium used for the identification of nitrate-reducing microorganisms, particularly aerobic and facultative anaerobic gram-negative bacteria, by detecting the ability to reduce nitrate to nitrite or further reduced nitrogen compounds. This medium is commonly used in clinical microbiology, food safety testing, and water quality analysis.

Prepared from a dehydrated base, Nitrate Broth contains peptone, meat extract, and potassium nitrate, and upon inoculation and reagent addition, allows for the detection of PYRase-positive organisms through colorimetric interpretation.

Key Features & Benefits

• ✅ Reliable Nitrate Reduction Detection – Distinguishes organisms based on metabolic capability to reduce nitrate
• ✅ Simple Colorimetric Interpretation – Red-orange color indicates presence of nitrites after reagent addition
• ✅ Secondary Confirmation with Zinc – Helps differentiate true negatives from further nitrate reduction
• ✅ Validated Against Reference Strains – Quality controlled with ATCC organisms
• ✅ Long Shelf Life (4 Years) – Stable under standard storage conditions
• ✅ Standardized pH (7.0 ± 0.2) – Optimized for bacterial growth and enzyme activity
• ✅ ISO-Aligned – Supports workflows referenced in ISO 11290-1 for food microbiology

Typical Composition (per liter)

Test Principle

Nitrate-reducing bacteria convert nitrate (NO₃⁻) into nitrite (NO₂⁻) or other reduced nitrogen compounds. After incubation, sulphanilic acid and alpha-naphthylamine are added:

• Red-orange color = Positive (nitrate → nitrite)
• No color change = Add zinc powder
  • Red after zinc = True negative (nitrate remained)
  • No red after zinc = Nitrate was reduced beyond nitrite → Positive

Product Specifications

Quality Control

Applications

🧪 Clinical Microbiology – Differentiation of Enterobacteriaceae and other gram-negative rods

🌊 Water Microbiology – Detection of nitrate-reducing bacteria in water samples

🥩 Food & Beverage Testing – Part of workflows for Listeria and spoilage organism identification

🔬 Industrial Microbiology – Nitrate metabolism assessment in microbial process control

🏥 Bacterial Taxonomy & Identification – Used in accordance with standard biochemical ID schemes

Ordering Information

Liofilchem® Nitrate Broth is a validated, user-friendly medium for conducting the nitrate reduction test, providing reliable support in the differentiation of gram-negative microorganisms across a range of industries. With its long shelf life, ease of preparation, and interpretive clarity, it is an essential tool for routine microbiological identification.