Want to know what bacteria is in the air when bottling?

[Shane Phelan]

I was telling a few people about this at the brewday in TOG yesterday. One of the guys that I work with was analysing how much bacteria fell in a given area (Petri dish) over a 90 minute period. He gave everyone in my lab a dish to try at home to expose for 90minutes.

I decided to expose mine while I was bottling beer as sometimes it is exposed for a while when siphoning and while in the bottling bucket. Here is a pic of what fell after 4 days in an incubator at 26 degrees.



Some of it is mould and the rest is mainly caused by "skin flora" which are common to every household. One of the science girls is going to analyse it in a bacterial database later to get a specific list of the species. 

The contamination concentration is proportional to the amount of airflow in the apartment/house. So any open vents, doors, fans etc will contribute more bacteria to the sample. As I was bottling I was moving around a fair bit, opening doors, washing bottles, carrying boxes in addtion to two PC's running with fans in both. So I see my sample as a kind of worst case scenario for my apartment....hopefully... Definitely recommended keeping your beer covered while cooling!

[Will_D]

Thats amazing! What particular nutient agar was that grown on?

Wouldn't mind some in the next GB!

[Shane Phelan]

I think its a general purpose agar mix. They also have other mixes specifically for growing yeast and other organisms but those types wasn't used for this test. All I can tell you is that it stinks and smells like science lab. 

[imark]

Wonder what and how much of each species is in there? Will we know if this could have any effect on the end taste of the bottled beer?

[Shane Phelan]

These are a couple of 'blank' slants from the TOG brew day a few weeks ago. I decided to see what would happen if I made slants from vials that had not been sanitised. I think they were open a few times. The first one is mould and the second looks to be more of that "skin flora" that was showing up on the plate earlier in the thread.

[Tom]

Mmm... skin flora.

[LordEoin]

I thought the crabs ate all that kinda stuff.... :