Millipore™ Dey-Engley Neutralizing Broth Powdered, NutriSelect® Plus, suitable for microbiology, 500g

Dey-Engley Neutralizing Broth (D/E Broth) is a non-selective, general-purpose liquid culture medium designed for the neutralization of a broad range of antiseptics and disinfectants during microbiological testing. Supplied as a powdered medium under the NutriSelect® Plus quality grade, it is widely used in environmental monitoring, disinfectant efficacy testing, sterility testing, and surface microbiology.

The formulation allows for effective recovery of microorganisms that may otherwise be inhibited by residual disinfectants, ensuring accurate assessment of bactericidal activity and reliable microbial growth detection.

Intended Use

• For microbiological and quality control testing
• Used in disinfectant and antiseptic efficacy studies
• Suitable for:
  • Environmental monitoring
  • Pharmaceutical microbiology
  • Food & beverage hygiene testing
  • Surface and equipment monitoring
  • Sterility testing workflows

Principle of the Medium

Dey-Engley Neutralizing Broth contains a balanced nutrient base combined with multiple neutralizing agents that inactivate a wide spectrum of disinfectants. This ensures that residual antimicrobial activity does not interfere with the recovery and growth of microorganisms present in the test sample.

Microbial growth is indicated by:

• Color change from purple to yellow due to dextrose fermentation
• Surface pellicle formation in non-fermenting organisms such as Pseudomonas spp.

Neutralizing Capability

The broth effectively neutralizes:

• Quaternary ammonium compounds
• Phenolic disinfectants
• Iodine and chlorine compounds
• Mercurials
• Aldehydes (formaldehyde, glutaraldehyde)
• Peracetic acid (PAA)

Key neutralizing components include:

• Sodium thiosulfate
• Sodium thioglycollate
• Sodium bisulfite
• Lecithin
• Polysorbate 80

Microorganism Suitability

Non-selective for the recovery of:

• Bacillus spp.
• Escherichia coli
• Pseudomonas spp.
• Salmonella spp.
• Staphylococcus spp.
• Coliforms
• General aerobic bacteria

Applications

• Disinfectant and antiseptic validation studies
• Environmental and surface microbiological monitoring
• Pharmaceutical cleanroom testing
• Food and beverage hygiene testing
• Sponge swab and surface sampling workflows
• Neutralization of disinfectants prior to microbial enumeration

Quality Grade

• NutriSelect® Plus
  • Standard QC-tested culture medium
  • Suitable for routine laboratory and industrial microbiology
  • Cost-efficient alternative to fully regulatory-certified grades

Product Specifications

Preparation & Directions for Use

1. Suspend 39 g of powder in 1000 mL of distilled water
2. Heat and boil gently to dissolve completely
3. Sterilize by autoclaving at 121 °C for 15 minutes (15 psi)
4. Cool to room temperature before use

Prepared medium should appear purple before inoculation.

Composition (g/L)

• Casein enzymatic hydrolysate – 5.00
• Yeast extract – 2.50
• Dextrose – 10.00
• Sodium thiosulfate – 6.00
• Sodium thioglycollate – 1.00
• Sodium bisulfite – 2.50
• Lecithin – 7.00
• Polysorbate 80 – 5.00
• Bromocresol purple – 0.02

Key Advantages

• Broad-spectrum disinfectant neutralization
• Supports recovery of stressed microorganisms
• Ideal for environmental and pharmaceutical microbiology
• Clear growth indication via color change
• Cost-efficient powdered format
• Trusted formulation for disinfectant validation studies

Dey-Engley Neutralizing Broth (NutriSelect® Plus) is an essential microbiological medium for accurate disinfectant efficacy testing and environmental monitoring. Its robust neutralizing capacity, broad organism compatibility, and reliable growth indication make it a standard choice for quality control laboratories, pharmaceutical facilities, and hygiene monitoring programs.