The cell surface of Mycobacterium avium-intracellulare and M. scrofulaceum: effect of specific chemical modifications on cell surface charge.

Cells of representative strains of the Mycobacterium avium-intracellulare and Mycobacterium scrofulaceum (MAIS) group had mixed cationic/anionic surfaces, unlike the surfaces of other mycobacteria. The pH electrophoretic mobility curves demonstrated that all MAIS strains examined had a net negative mobility above pH 3.5-4.5 and a positive mobility below that pH range. Based upon the pH electrophoretic mobility of cells following chemical or enzymatic treatment, it appears that the surface molecules contributing to charge are amino groups (primarily contributed by proteins), carboxyl and phosphate (and phosphodiester-linked) groups.