Abstract: This invention is directed to applying a low sedimental fluid shear environment to manipulate microorganisms, and to microorganisms and compositions obtained based on such manipulation. Specifically, the present invention provides methods of modifying a molecular genetic or phenotypic characteristic (e.g., virulence, stress resistance or biofilm formation) of a microorganism by culturing in a low sedimental shear environment. One or more ion concentrations in the culture can be modulated in order to inhibit or amplify the extent of the modification. The present invention also provides microorganisms obtained from a low sedimental shear culture, which exhibit modified and desirable phenotypic characteristics, as well as therapeutic, vaccine and bioindustrial products prepared from such microorganisms.