[Daephos (OP)]

My fridge is infested with a type of pink colored mold (bacteria, actually), that has been growing lately on food stored in containers. Such as: yogurt, hummus, cream cheese. It does not appear to be affecting other foods stored there.

Q. 1: What I don't understand, is how it is getting into the -sealed- containers! I did not use the same (stainless) utensils in all of the containers.

Q. 2: It got into the block of cream cheese. The exterior is almost white, but the interior of the cheese is very pink! What I also don't get, is that the walls of the compartment where the cream cheese was are stained pink! And there are even straight pink lines on the carton of the cream cheese that are hard to come off. But I don't think its printing on the carton, but that damn pink bacteria!

So.. how does it get into sealed containers, why/how is it staining plastic walls and cardboard boxes, and is there any way to get rid of it for good?! I read even bleach may not be effective.

[chris]

pink colored mold (bacteria, actually),

Moulds are members of the fungus family tree; bacteria are prokaryotes, a very different form of life. Do you know it's bacterial? I ask since most brightly-coloured, cold-spreading organisms that thrive in damp conditions like the fridge are often fungal species related to the ones that make cheese go blue and rotten oranges grow a fluffy coating.

However, there is also a bacterium similar to E. coli called Serratia marcescens. This forms reddy-pink coloured growths in damp places like bathrooms and toilets. It can cause human infection, most frequently in the urinary and respiratory tract, but is also a colonising organism living in the intestine. Here's a link to the relevant page on wikipedia that will tell you more: https://en.wikipedia.org/wiki/Serratia_marcescens

I would recommend emptying your fridge and giving it a good clean. Bleach might be necessary!

[evan_au]

how does it get into sealed containers?

If there are spores floating in the air of the kitchen, when you put the food in the containers, some spores will get in, too.

Try an experiment: buy two identical items from the supermarket, hermetically sealed in a clear plastic container (eg two packets of cheese).

• Open one, and put it in one of your usual containers.
  
• Don't open the other packet, and put it in one of your usual containers
  
• Place both containers in the fridge
  
• Then watch to see if one or both (or none) are affected by the pink organism.
  
• A sample size of one is not very good evidence, but a series of experiments might diagnose the source of the problem

[Daephos (OP)]

Chris: Do you know it's bacterial?

I don't know squat. That's why I'm here! I just read that pink is bacteria...

"What we tell our biology classes is that whitish grey or greenish plaques are mold (fungus), and yellow, white, or pink plaques are bacteria. Also, mold has a fuzzy look ("fungus is fuzzy") and bacteria is shiny. "

My pink 'mold' is not fuzzy. After getting inside two boxes of cream cheese, it stained all the walls of the butter compartment in the fridge door... which I've never seen common (green) mold do.

So bleach should be enough to kill this stuff? Do I have to empty out the freezer compartment too?


evan_au: Try an experiment:

I note that although it was first spotted on yogurt, and was also seen on cream cheese, it happily travelled to and spread inside of a store bought container that contained home-made hummus (chick pea dip). Which has no milk cultures at all. But it was getting older and liquidy.

But, it was discovered inside two yogurt containers, bought at seperate times, seperate places. The containers were the ones the commercial yogurt came in. So it somehow travelled inside both containers. Now I don't know if these things can get inside an opened yogurt container in the fridge, with the cover on. Perhaps because the yogurt container cover doesn't make an extremely tight seal, perhaps they get in? But if not, that suggests the spores are in the kitchen, and travelled inside the containers when they were out of the fridge and open.

I think they are definitely travelling somehow from one container/package to another in the fridge environment, regardless of any possibility of contamination of the container/package the food is in. My guess is they may have originally come from the cream cheese packages I bought when I had traveleld to the U.S. The interior of this stuff was thoroughly colored with pink veins. Even the box and compartment around it.

[chiralSPO]

Before spraying bleach all over your fridge, you should try wiping all of the inside surfaces down with high proof grain alcohol (195 proof = 97.5% ethanol). This will almost certainly kill any nasties without leaving a residue that could be toxic to you...

[Bored chemist]

When bleach dries it just leaves a little salt behind.
And it does kill all known germs.

[chiralSPO]

When bleach dries it just leaves a little salt behind.
And it does kill all known germs.

Absolute alcohol kills 99.99% of known germs, and when it dries it leaves nothing behind...

[chris]

Absolute alcohol kills 99.99% of known germs, and when it dries it leaves nothing behind...

Not quite; non-enveloped viruses, like adenovirus, enterovirus and norovirus, as well as some spore-forming organisms, are profoundly resistant to alcohol; bleach - including hydrogen peroxide - is the only thing that will get rid of them.

This is the irony of the alcohol gel dispensers that are proliferating all over the place in public spaces. Ostensibly to stop people getting norovirus infections, the isopropanol and ethyl alcohol in these gels will very nicely destroy everything else on the skin leaving behind a nice pure culture of noro... Soap and water (A running tap), in clinical trials, couldn't be beaten!

But, for the fridge, peroxide or a hypochlorite, which as Bored Chemist says will degrade harmlessly to dilute sodium chloride, is the recommended treatment.