Bacteria are a singe celled living organism that's not that dissimilar from our own cells.

They are everywhere all the time. Nothing produces them, they are living things and multiply on their own. They don't mate and have offspring like animals, they use binary fission and essentially just grow another one of themselves and then split into two.

Yeah I kind of get that but what I dont understant its their reach and number like lets say I cook some meat and then I desinfect in a way I can assure there are not any bacteria, then I put in a drawer, the kind you open once a year and place it there, im sure if I come back 2 days later it has gone bad, how do they got there? what has keep them alive in a drawer or how do they manage flying through the air without any food?

Sorry, first thing thanks for your reply

Are you really sure there's no bacteria there? Unless you absolutely drench it in alcohol, there are very good chances something will survive. Even the meat itself it's going to be completely sterile unless it's burnt to a crisp. And ask yourself about other things, what did you use to transfer the meat to the drawer? Doesn't matter if it's only a couple cells that survive, they will immediately get to work on the steak and soon you'll have an entire colony.

And yes, they can also be blown about by air currents and land on the steak, they can do without food for a couple of minutes.

Let's say you bought a bunch of meat, cooked it, disinfected it, and put it away somewhere. It's 100% bacteria-free(which in reality, it's probably not). If you put it in a completely sealed, sterilized container, then it's not gonna rot. it might not taste good after a while since the protein, muscle, fat, water and stuff might not retain their original structure.

but we normally don't have that kind of container at home. if you put it in....let's say...a drawer, even if the meat is bacteria-free the drawer is probably not, even if it's, some bacteria might get in through the air or airborne water droplet or even walk themselves in there.

Even if it's just a few, they will eat your meat and make more of itself(using your meat they just ate), you won't notice at first, but the number of bacteria grows exponentially, and at some point, there will be so many bacteria eating away your meat that you might be able to see a few colonies of them.

basically, nothing is producing bacteria, they produce themselves using whatever they can eat(in this context, your meat), just a few individuals can turn into billions in a few days.

This idea applies to other microbes that grow on your food as well. like Fungi, other eukaryotes, etc.

>what has keep them alive in a drawer or how do they manage flying through the air without any food?

Coughed? Bacteria in the air. Sneezed? Bacteria in the air.
Standing near someone who splits a little while talking? Bacteria in the air and on your clothes. Sudden movement that shakes those bacteria from your clothes -> bacteria in the air.

Even if it's not in the air and you use sterilised gloves, as soon as you touch anything that isn't sterilised you have bacteria on your hands and transfer them to the steak when touching it.
And so on.

Ok I got it, thanks!