BPRM Broth Base (Bacteroides Phage Recovery Medium)

This medium allows faster bacterial growth and produces higher phage yields. Peptone and tryptone provide nitrogen, vitamins, amino acids and the nutrients for growth. Glucose is the fermentable carbohydrate, which is a carbon and energy source. Yeast extract is a source of vitamins, particularly of the B-group. Sodium chloride maintains the osmotic balance and magnesium sulfate heptahydrate is the buffering agent in the medium.

With the adequate concentration of agar, a semi-solid or a solid medium can be prepared. To inhibit the accompanying flora, add 100 mg/mL of kanamycin and 7.5 mg/mL of vancomycin sterilized by filtration.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 29.42 grams of the medium in one liter of distilled water. Add 1 mL of calcium chloride 5%. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize at 121 °C for 15 minutes. Cool to 45-50 °C. Aseptically add 1 mL/litre of 1% hemin sterile solution prepared in 0.02% NaOH. Mix well. Just before use, add 25 mL/litre of a sterile solution of 10.6% (w/v) disodium carbonate. Adjust the pH to 7.0 with HCl.

Instructions for use

1. Take the inoculum with a sterile loop.
2. Submerge the loop into the medium and shake gently.
3. Incubate at 44 ± 1 °C for 21 ± 3 hours.

• ISO 10705-4 Water quality - Detection and enumeration of bacteriophages - Part 4: Enumeration of bacteriophages infecting Bacteroides fragilis.
• Donia D., Divizia M., Panà A. Analysis of concentration methods for bacteriophages. Moderna, 1998, 109:1.
• Tartera C., Jofre J. Bacteriophages active against Bacteroides fragilis in sewage-polluted waters. Applied and Environmental Microbiology, 1987, 53, 1632.