Antibiotics properties

Toxic to bacteria but not to fungi. Antibiotics thermo-resistant to autoclaving are used, e.g. Gentamycin. Other antibiotics (e.g. penicyllin) must be added at agar cooling, between 40 and 60 degree. Dosage is specific to antibiotic. Gram-positive and Gram-negative antibiotics may be combined.

Antibiotics classes

  • Beta-lactam antibiotic
    • Penicillin : usually against Gram-positive bacteria. 0.5 g/l (see this link)
    • Cephalosporine: predominantly against Gram-positive bacteria, and successive generations increased activity against Gram-negative bacteria.
      • Cefixime : 0.05 mg/l. Non-autoclavable, add at 50C (see this link). Third generation (Gram-postive + Gram-negative), bactericidal (store 15 - 30C). Liquid suspension active 15 days and maybe refrigerated
    • Ampicillin: 0.1 mg/l. Non-autoclavable (see this link). Only effective against Gram-positive.

  • Aminoglycoside
    • Gentamycin : Thermoresistant to autoclaving. Against Gram-negative. 0.05g/L[1].
    • Streptomycin : 0.3 mg/l. Non-autoclavable (see this link). Liquid spray of 30 mg/l. Broad-spectrum antibiotic, inhibits both Gram-positive and Gram-negative bacteria. 0.5 g/L (see this link)
      • Dihydrostreptomycin : 50 mg/l. Autoclavable (see this link).

  • Others
    • Azithromycine : 2 mg/l (see this link). more effective against certain Gram-negative bacteria.


  1. ^ Growing Gourmet and Medicinal Mushroom, by Paul Stamets, P478