DNA

Difco Nutrient Agar (DNA)

Difco Nutrient Agar is a rich medium commercially available from BD and routinely used for cultivating many non-fastidious organisms. It contains beef extract and peptones; exact composition will vary between batches.

Many Streptomyces sp. grow well on DNA, but developmental and/or antibiotic production phenotypes may differ compared to growth on other media (e.g. SFM).

Preparation

Per Litre:

• 4g Difco Nutrient Broth Powder
• 10g Agar
• 1L dH₂O

Instructions

1. For solid medium, add 0.8g of DNB powder into each 250ml conical flask
2. Add 2g of Agar
3. Add 200ml dH₂O
4. Autoclave

Uses

• Streptomyces Colony PCR (see High GC PCR for instructions)
• Spore titres
• Re-isolation experiments
• Selection for resistance to salt-sensitive antibiotics

Notes

For growth in liquid culture, DNB can be made without the agar.