2 replies to this topic

[aliothsan]

I am wondering how fast tetracycline tends to break down when exposed to light. I heard offhandedly that when you're storing Tet media "long term" it needs to be in the dark, but for just growing up overnight cultures it is fine to be in the light. Can anyone confirm, or provide actual numbers?

[cellcounter]

aliothsan, on Aug 10 2009, 10:15 AM, said:

I am wondering how fast tetracycline tends to break down when exposed to light. I heard offhandedly that when you're storing Tet media "long term" it needs to be in the dark, but for just growing up overnight cultures it is fine to be in the light. Can anyone confirm, or provide actual numbers?

I can not provide actual numbers, but if you are growing bacteria in overnight culture, you should be just fine, whether you are using it as an antibiotic or inducinng agent. Over long periods it does break down, and results in lowered antibiotic activity, but there is no data (so far as I know) that it loses its inducing activity.

When searching lit, be mindful of that phrase "light sensitivity" may have been used in two different contexts:

1. Light sensitivity caused to skin, after application/ingestion of tetracyclines as antibiotics.
2. Compound degradation caused by sensitivity to light.

[GeorgeWolff]

Suggest you run controls to validate your media holding criteria.  As was said above, tet has been associated with light sensitization but not that much with innate light instability.

That said -many selective/differential media can provide different results if exposed to light - EMB, Rose bengal.