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I have found some small white dots on an old sausage somewhere in my fridge which I claimed to be bacterial colonies. I was right. I made some photos of them in 2000x. Do you know what type of bacteria can they be? I know it can be hard without all the identify tests.

Those are more likely a yeast growth. Yarrowia Lipolytica is a common one which feeds on the fat. There are many others.

Oh, it can be. I was a bit confused by the size of them, bacteria are usually smaller.

It also depends on what kind of sausage they are. I am assuming that you are talking about some form of cured sausage. There are two ways that cured sausage is judged to be "cured". For some, those that have been given a limited fermentation, it is based on water activity. The lower the water activity, the less likely it would be for opportunistic yeasts to grow. High water activity sausage have a limited shelf life and it is mostly yeasts that colonize them, followed by other breakdown organisms. This is considered to be spoilage.

The other way is by ph. Fully fermented sausage, such as traditional summer sausage is dried and smoked below a specific water activity threshold and as well fermented to a very low ph. Due to the low ph, they can be left with a higher moisture content. Mostly, various species of lactobacteria abound in them based on the innoculant used but if left in an undesirable environment they can absorb humidity and then yeasts that can tolerate a low ph will colonize them. This bloom, isn't really considered to be spoilage when on the surface but it does change the character of the sausage and if left too long spoilage bacteria will follow suit.


Most commercially made cured sausage is processed in such a way as to leave as much water and therefore profit in it as is possible, so industrial techniques such as high nitrate/nitrite content, high salt,sometimes cooking,immaculate refrigeration and vacuum packing are used to overcome the sausage's vulnerability to spoilage. Once even one of those controlled conditions is removed...air, higher temperature, spoilage begins quickly.

Authentic sausage is made in such a way that it has a long shelf life unrefrigerated. That was the point of it existing in the first place.
We make between 500 and 1000 lbs. of mini pepperoni, kaminwurz and altewurz a year as part of our farm production. There are no nitrates used; ascorbic acid instead, and each type is dried or fermented to an ideal state. The shelf life is considered by federal inspection to be 9 months unrefrigerated.

We make between 500 and 1000 lbs. of mini pepperoni

How do I get my hands on some? Do you export to the US?

Your sausage production sound really nice. If you want to know, this were sausages I am talking about, with 95% ham content, but they weren't dried.
https://ezakupy.tesco.pl/groceries/pl-P ... 3120578844

The second ingredient on the list is starch, which in addition to being a binder, absorbs water and fat, keeping it in suspension. After a period of storage the fat and water become available to yeasts which begin the process of consuming the sausage for you, by initially feeding on the sugars, although specific species thrive on fat. Bacteria which can withstand deep refrigeration( likely species of psychrotrophs) soon follow up, after the yeast lay out a red carpet for them.
It's a very friendly and party like atmosphere for a while; lots of singing and dancing, pirouettes ,sachets. Thousands get married, have children, make inebriated pronouncements from one of the many podiums until eventually a fly arrives. A monstrous mega-airship bristling with it's own bacterial airborne and hundreds of white canisters of fly DNA are unloaded. That's it . The parties over.