The bacteria are essential for the production of bad smell intrinsic.

The bacteria are essential for the production of bad smell intrinsic, but not all odors emanating from the mouth are caused by microorganisms, the food can affect the smell of your breath and mouth , common examples include the extrinsic smell of onions, garlic and alcoholic beverages, meals and drinks as they produce volatile fatty acids and other substances with a foul odor that are excreted through the lungs during normal breathing.
The physiological halitosis is temporary and occurs when volatile substances are brought by-haematological odoriferous foods, and the drinks are released into the lungs. The metabolism of certain foods such as onions, garlic, alcohol and cured meats (e.g. pastrami), are absorbed in the intestine, metabolised in the liver, released into the bloodstream  and excreted through the lungs resulting in a characteristic halitosis.