[rosaclinic]

Bacteria, indeed, have retained their predominant position and hold sway not only by virtue of a long and illustrious history but also for abundant reasons of contemporary vigor. Bacteria give yogurt its tangy flavor and sourdough bread its sour taste.

Bacteria, and other micro-organisms are essentially important in the cycling of nutrients and energy, particularly in the breakdown of dead organic matter to make the resources locked up in things like dead trees available again to other living organisms.

They also play a central role and the fixation of atmospheric Nitrogen into organic molecules and in the cycling of minerals such as Carbon and Sulfer. Bacteria also make, or help to make, drugs, hormones, or antibodies