View source for Antibiotic stocks and working concentrations

The following antibiotics can be used for selection at these concentrations in many <em>Streptomyces</em> sp. (If working with a new species, you should always first check whether it has intrinsic resistance to an antibiotic before attempting to use it. Generally speaking, apramycin and hygromycin are likely to be more useful as selective markers than e.g. kanamycin and carbenicillin.)

{| class="wikitable"
! style="font-weight:bold; background-color:#c0c0c0;" | Antibiotic
! style="font-weight:bold; background-color:#c0c0c0;" | Stock [mg/ml]
! style="font-weight:bold; background-color:#c0c0c0;" | Final concentration [µg /ml]
|-
| Apramycin
| style="text-align: center;" | 100 in dH<sub>2</sub>O
| style="text-align: center;" | 50
|-
| Carbenicillin<sup>1</sub>
| style="text-align: center;" | 100 in dH<sub>2</sub>O
| style="text-align: center;" | 100
|-
| Chloramphenicol
| style="text-align: center;" | 25 in 100% EtOH
| style="text-align: center;" | 25
|-
| Cycloheximide<sup>2</sup>
| style="text-align: center;" | 25 in 100% EtOH
| style="text-align: center;" | 25
|-
| Hygromycin<sup>3</sub>
| style="text-align: center;" | 50 in dH<sub>2</sub>O
| style="text-align: center;" | 100
|-
| Kanamycin
| style="text-align: center;" | 50 in dH<sub>2</sub>O
| style="text-align: center;" | 50
|-
| Nalidixic acid
| style="text-align: center;" | 25 in 0.2N NaOH
| style="text-align: center;" | 25
|-
| Thiostrepton
| style="text-align: center;" | 50 in 100% DMSO
| style="text-align: center;" | 50
|}

<strong>Notes:</strong>

<sup>1</sup>Carbenicillin is more stable than ampicillin, but care should still be taken to avoid excessive freeze/thaw cycles which could result in degradation of the antibiotic.

<sup>2</sup>Cycloheximide is toxic, prepare the solution in a fume hood and take care when handling

<sup>3</sup>Hygromycin selection is salt-sensitive; on low-salt media such as [[DNA]], 50 µg /ml (final concentration) is sufficient for selection.