Overview:
Bushnell-Haas Broth (also known as Bushnell-Haas Medium) is a mineral salts broth serving as a basal medium for the isolation, enumeration, and study of hydrocarbon-degrading microorganisms. Originally developed by Bushnell and Haas in 1941, it supplies essential inorganic nutrients (nitrogen, phosphorus, sulfur, magnesium, calcium, and iron) without a carbon source, necessitating supplementation with hydrocarbons such as kerosene, mineral oil, paraffin wax, or gasoline to promote growth. This selective formulation is particularly valuable in environmental microbiology for assessing microbial biodegradation of petroleum products, with growth indicated by turbidity in liquid cultures. The neutral pH environment simulates natural conditions, supporting bacteria like Pseudomonas spp. that metabolize hydrocarbons as their sole carbon and energy source.
Applications:
?? Detection and enumeration of hydrocarbon-utilizing bacteria in fuel, soil, water, and oil spill samples
?? Bioremediation research, including degradation of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH)
?? Microbiological quality control of aviation fuels, lubricants, and petroleum-based products
?? Studies on microbial ecology, hydrocarbon utilization kinetics, and fuel contamination analysis
Key Features:
?? Carbon-free basal composition ensures selective growth solely on supplemented hydrocarbons
?? Provides trace minerals and buffered pH for optimal viability of degradative bacteria like Pseudomonas aeruginosa
?? Suitable for turbidimetric assays and enrichment prior to plating on agar versions
?? Endorsed in ASTM, EPA, and SIM protocols for fuel microbiology and environmental remediation
?? Normal post-autoclave precipitate (yellow-orange) confirms proper preparation without affecting performance
Composition (per liter):
Magnesium Sulfate (MgSO?�7H?O) � 0.20 g
Calcium Chloride (CaCl?, anhydrous) � 0.02 g
Monopotassium Phosphate (KH?PO?) � 1.00 g
Dipotassium Phosphate (K?HPO?) � 1.00 g
Ammonium Nitrate (NH?NO?) � 1.00 g
Ferric Chloride (FeCl?�6H?O) � 0.05 g
Final pH: 7.0 � 0.2 at 25�C
Preparation:
Suspend 3.27 g of the dehydrated medium in 1 liter of distilled or purified water. Heat gently with frequent agitation if necessary until completely dissolved (a white precipitate may form initially). Dispense into tubes or flasks. Autoclave at 121�C (15 psi) for 15 minutes. Upon cooling, a yellow to orange precipitate is normal and does not indicate spoilage. The prepared broth should be colorless to slightly opalescent with a slight brown sediment. For use, aseptically add the hydrocarbon supplement (e.g., 1-2 ml sterile mineral oil per tube) and inoculate.
Storage:
Dehydrated medium: Store in a tightly closed container at 10�30�C, protected from moisture and light; stable until expiry date (typically 3�5 years).
Prepared broth: Store at 2�8�C in sealed containers; use within 2 weeks. Discard if turbid without inoculation, contaminated, or if pH deviates.
?? For laboratory and research use only. Not for diagnostic procedures without proper validation. Not for human or veterinary consumption. Handle in a fume hood when adding hydrocarbons; autoclave waste before disposal. Not intended for non-hydrocarbon-degrading organisms without supplementation.