BHI Broth: Brain Heart Infusion Broth

Brain Heart Infusion (BHI) broth is a liquid medium used in microbiology for the cultivation and maintenance of a variety of microorganisms, including bacteria and fungi. It is a rich medium containing nutrients that support the growth of a wide range of organisms. The components of BHI broth typically include beef heart infusion, calf brain infusion, peptones, and dextrose.

Brain Heart Infusion Broth

It provides a nutritious environment that promotes the growth of fastidious microorganisms or those with complex nutritional requirements. The earliest version of brain heart infusion media was made in 1899 when Edward Rosenow combined dextrose broth with calf brain tissue to grow streptococci.

Brain Heart Infusion Broth composition

Brain heart infusion broth composition plays a crucial role in supporting the growth of various bacteria and fungi. The specific formulation may vary slightly between manufacturers, but the core components typically include:

  • Beef Heart Infusion: This provides a source of amino acids, peptides, and other nutrients essential for microbial growth.
  • Porcine Brain Infusion: The brain infusion contributes additional nutrients and growth factors necessary for the cultivation of a wide range of microorganisms.
  • Infusion from Calf Brains: Some formulations may include infusion from calf brains, adding to the richness of the medium.
  • Peptic Digest of Animal Tissues: This component provides a digest of animal tissues, offering a mix of proteins and other organic substances that serve as nutrients for microbial development.
  • Sodium Chloride: To maintain the osmotic balance of the medium, sodium chloride is added in appropriate concentrations.
  • Dextrose: Dextrose, a simple sugar, serves as an energy source for microorganisms during their growth in the medium.
  • Disodium Phosphate: This salt contributes to the buffering capacity of the medium, helping to maintain a stable pH level.
  • Agar (if solid medium is desired): If agar is added, it solidifies the broth, creating. Brain Heart Infusion Agar, is suitable for the cultivation and isolation of microorganisms.

It’s important to note that the precise brain heart infusion broth composition might vary, and some formulations may include additional components or exclude certain ingredients based on the intended use of the medium. Sterilization is a crucial step in the preparation of Brain Heart Infusion Broth to eliminate any potential contaminants and ensure a suitable environment for microbial growth.

IngredientsGms / Litre
Enzymatic Digest of Animal Tissues10.0
Dehydrated Calf Brain Infusion12.5
Dehydrated Beef Heart Infusion5.0
Glucose2.0
Sodium Chloride5.0
Disodium Hydrogen Phosphate, Anhydrous2.5
Final pH7.4 ± 0.2
Brain Heart Infusion Broth composition

Brain Heart Infusion broth Principle

The Brain Heart Infusion (BHI) broth is a microbiological culture medium designed to provide a rich and nutritious environment for the growth of a wide variety of microorganisms. The principle behind BHI broth lies in its carefully balanced composition, which includes key ingredients to support the thriving of bacteria and fungi.

Principle of Brain Heart Infusion Broth:

  1. Nutrient-Rich Medium: The primary principle of BHI broth is to serve as a nutrient-rich medium. It contains components such as beef heart infusion, porcine brain infusion, and peptic digestion of animal tissues, which collectively provide essential amino acids, peptides, and organic substances crucial for microbial growth.
  2. Versatility in Supporting Microorganisms: BHI broth is formulated to support the growth of a broad spectrum of microorganisms. The combination of ingredients creates an environment conducive to the cultivation of both fastidious and non-fastidious bacteria, as well as fungi.
  3. Adaptability to Different Strains: The versatile nature of BHI broth allows it to adapt to the specific requirements of different microbial strains. This adaptability makes it a preferred choice in laboratories where diverse microorganisms need to be cultured for various purposes, including research and diagnostics.
  4. Buffering Capacity: Disodium phosphate, included in the formulation, contributes to the buffering capacity of the medium. This helps maintain a stable pH level, ensuring optimal conditions for microbial growth.
  5. Osmotic Balance: Sodium chloride is added to the medium to maintain the osmotic balance. This is essential for preventing osmotic stress on microorganisms and ensuring their proper development.
  6. Facilitating Microbial Studies: BHI broth is commonly used in microbiological research, clinical diagnostics, and antibiotic susceptibility testing. It provides an ideal platform for the isolation, propagation, and study of various microorganisms, aiding researchers and clinicians in understanding their characteristics and behaviors.
  7. Supporting Diagnostic Procedures: In clinical settings, BHI broth is instrumental in diagnostic procedures. It allows for the cultivation and identification of pathogens, aiding in the diagnosis of infectious diseases.
  8. Optional Solid Medium (BHI Agar): The principles extend to BHI Agar when agar is added to create a solid medium. BHI Agar is particularly useful for the isolation and enumeration of microorganisms.

Brain Heart Infusion Broth Preparation

  • Suspend 37 g of the powder in 1 liter of distilled or deionized water.
  • Mix well.
  • Heat to boil shaking frequently until completely dissolved.
  • Distribute into final containers.
  • Sterilize in an autoclave at 121°C for 15 minutes.

Brain Heart Infusion broth Procedure

  • If material is being cultured directly from a swab, insert the swab into the broth after inoculating plated media.
  • For liquid specimens, transfer a loopful of the specimen into the broth medium using a sterile loop or aseptically pipette the specimen onto a plated medium and into the broth.
  • Examine for growth after 24-72 hours of incubation.
  • It is recommended that liquid media for anaerobic incubation should be reduced before inoculation by placing tubes (with loosened caps) under anaerobic conditions for 18-24 hours.
  • Alternatively, the media may be reduced by bringing the media up to 100°C in a boiling water bath.
  • Loosen screw caps slightly before heating, and tighten during cooling to room.

Brain Heart Infusion broth result

After the incubation period examine tubes for turbidity which is an indication of growth. If desired the broth can then be sub-cultured onto an appropriate solid medium for observance of colony morphology and so that further tests can be performed on isolated colonies.

  • If BHI broth is used to culture yeasts or fungi a prolonged incubation period may be required to obtain good growth.
  • Since the nutritional requirements of organisms vary, some strains may be encountered that fail to grow or grow poorly in this medium.
  • Turbidity indicates microbial growth.
  • The coagulase test is considered positive if the clot volume is more than half of the original liquid volume.

Brain Heart Infusion Broth Storage

The powder is very hygroscopic, store the powder at 10-30°C, in a dry environment, in its original container tightly closed. Store bottles and tubes at 10-25°C away from light. Do not use the product beyond its expiry date on the label or if product shows any evidence of contamination or any sign of deterioration.

Brain Heart Infusion Broth Quality Control

Organism TestedResultsTime
Bacteroides fragilisGrowth24 hrs
Prevotella melaninogenicaGrowth24 -48 hrs
Bacteroides vulgatusGrowth24 hrs
Fusobacterium nucleatumGrowth24 hrs
Fusobacterium necrophorumGrowth24-48 hrs
Clostridium perfringensGrowth24 hrs
Clostridium novyiGrowth24 hrs
Peptostreptococcus anaerobiusGrowth24 hrs
Clostridium difficileGrowth24 hrs
Staphylococcus aureusGrowth24 hrs

Can Brain Heart Infusion be used for both bacteria and fungi?

Yes, Brain Heart Infusion is formulated to support the growth of both bacteria and fungi, making it versatile for various microorganisms.

What precautions should be taken when working with Brain Heart Infusion?

Proper sterilization and adherence to aseptic techniques are essential to prevent contamination when working with Brain Heart Infusion.

How long is the shelf life of Brain Heart Infusion?

When stored properly, Brain Heart Infusion has a long shelf life. Following recommended storage conditions and expiration dates ensures its efficacy.

What is the role of Brain Heart Infusion in clinical diagnostics?

In clinical diagnostics, Brain Heart Infusion is used for the cultivation and identification of pathogens, aiding in the diagnosis of infectious diseases.

Is Brain Heart Infusion suitable for antibiotic susceptibility testing?

Yes, Brain Heart Infusion is widely employed in antibiotic susceptibility testing to assess the effectiveness of different antibiotics against specific microorganisms.

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