h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I ask becuase in my job in the laboratory , I regularly have to squirt things down with disinfectants and bleaches and 70% ethanol.

So the other day I was wiping down the trolly I use to go in and out of the labs and as I wiped up the cloth a little line of white sort of froth followed.

Now in my mind, I thought something like the forum title, "it's working" felt momentarily quite satisfied, imagining all the little bugs exploding and dissolving into a sterile froth - but then I caught myself. Is that what was really happening or does nothing at all happen when you disinfect something. Was the slight suggestion of froth just an artefact of having a wet surface being rubbed with a cloth - and why was I making this association with the fizzing white bubbles and it being "clean"?


Anyway much to ponder there for the SExists.

So over to you guys.

Many bleaches and disinfectants do form a lather when mixed with water. But the same would happen if you poured sterile distilled water into a sterilised beaker containing disinfectant. It's not a product of germs dying.

Just a lather then? Ho-hum.

Ah, but what was the trolley used for before you got in a lather over it?

It's a transport trolley, so I move sorts round the lab, clean and dirty glassware (prior to autoclaving), making deliveries of orders and unpacking boxes. It also used to move out the confidential/ contaminated waste to the recycle area outdoors.

So potential to pick up stuff from the environment is quite wide and since it goes into some sensitive areas where contamination is an issue, so that's why I disinfect it.

Fair enough Clive - plenty of scope for something less usual then, to mix up with whatever else, & be spread around...


Out to the car park with it. Rubber suit & hood. Hosepipes. Long-handled scrubbers. Selection of acids. Selection of alkalis. Sand.
A nice fluffy, warm towel and a before taking it back.

It's probably just several million bacteria waving little white flags. Nothing to worry about.

Presumably you are using an equivalent to Precept which is what we use as standard in our labs?

As far as I'm aware this stuff is manufactured to be used at the scene of road accidents and the like to decontaminate large areas of spilled blood and the like (yeah, I know ).

The foaming action of precept is very strong and is not to 'work' as such but to make sure it spreads the disinfectant to every nook and cranny of the areas that has been treated.

Distel (formerly Trigene) and also 70% Ethanol / H2O. I use Virkon for disinfecting the glassware which is like powdered bleach, which I make up to a 2% solution.

However, I've noticed the same thing when using bleach at home, if I make up bleach n water in the sink, then wash somethign I suspect is dirty in it, I'll often see white 'tendrils' forming in the water.

I've often thought that was the trail of dead and dying wotsits coming off.

However as I said in the OP this was just a thought, and I've only just recently begun wondering if it was true.

I am slightly concerned about 70% ethanol solution.

Bacteria can form spores which are almost indestructible under certain conditions and high alcohol solutions can cause spore formation. Hence we are taught not to use higher that 20% solutions for disinfection purposes. I wonder why they are getting you to use this

Mind you, disinfection is rather different from sterilisation which is what Precept and its ilk are for.

I'll mention that to my manager Orcus, any particular species / strain of bacteria?

Well E. coli can't do it which is I imagine the most likely one you are using (which is why I said I was only slightly concerned) - Bacillus is the most common one that can spore that you may encounter. Bacillus subtilis is used reasonably often in labs although nowhere near as often as E. coli.

I wouldn't worry too much about it - if you're using a bleaching agent too then you don't have much chance of contamination provided it's all done thoroughly
http://en.wikipedia.org/wiki/Endospore

Yeah different bleaching and disinfectant agents are used too in a cyclic revolving process.