Bacteria are competitive little beasties, and occupy every nook and cranny of earths biosphere, and beyond. In fact there are more than ten times the number of bacteria to cells in our body, and quantifying the number on earth would run into the trillions of trillions. They are an essential part of our living, and breathing, planet.
Scientists use these little critters to signify the presence of life on other planets, while personally living in a chaotic mix of them existing in colonies and crevices all around them. If bacteria paid rent on their living space, we would all be rich! Fortunately, they are microscopic, and we don't have to keep track of most of them
Bacteria come in various shapes and sizes. Some are little rod shaped critters, some spherical, and they can even be a spiral shape. Bacteria have taken two distinct evolutionary pathways, and the most remarkable thing about them is their ubiquitous diet, which can vary from metalic substrates to solar, and from deep in the earth to occupying important strata of the oceans. Most bacteria just munch away at their favorite buffet, and contribute to the balance of nature. Some are our deadly enemy, and we should maintain a healthy immune system to help keep them from employing us as lunch. Of course, if we do prepare food for dinner that has bacteria already in residence, we can kill them with proper cooking.
Bacteria have an appetite for various, and frequently, specific substrates. Sugars of various kinds can be used to identify them, and may help to indicate their infectious or non-infectious nature. If bacteria are denied their primary diet, they don't do very well. In the case of those that might infect our urinary system, if the host takes in an appropriate amount of D-Mannose, it works against that infection as that is not the preferred diet of certain bacteria prone to cause a problem there. However, medical doctorsshould always be consulted before trying to combat most health problems on their own. The majority of bacterium dance along with our physiological life processes, and we never feel their tickle anywhere, although they are an intrinsic part of our inner and outer anatomy.
Ruminants have a different set of microbes that help their digestion than we do. We do not break down cellulose fibers as well as cows because of this difference. You might say "vive le difference." Our extremely variable diet is assisted from one end to the other by a huge number of microbial workers, that help with digestion and absorption.
It is likely bacteria live in any environment you can make up, or have read about. Some cannot live without oxygen, and many are anaerobic. Some require sunlight, and others darkness. Dry or wet will satisfy others.
The planet earth, and all of us on it, would not be here at all without our invisible partners in life, the incredible world of bacteria.