GROWTH PROMOTION OF MYCOBACTERIUM-AVIUM MYCOBACTERIUM-INTRACELLULARE COMPLEX BY ENTEROBACTERIAL ACETATE

mycobacterial growth factor was present in the conditioned media of Es cherichia coli and Enterobacter cloacae cultures, but not in Pseudomon as aeruginosa culture. This factor potentiated the growth of Mycobacte rium avium-M. intracellulare complex (MAC), a patient isolate, and wel l-established strains of M, avium and M. intracellulare. The growth fa ctor was not a polypeptide; it was heat-stable and possessed a molecul ar weight < 500 D. Acetate production by enterobacteria was responsibl e for the biological activities observed. Acetate promoted mycobacteri al growth at concentrations up to 3 mM; higher levels were toxic. The effects of acetate on MAC growth were not influenced by the pH of the media. Our data suggest that production of acetate by enterobacteria m ay regulate mycobacterial growth, and therefore, intestinal acetate mi ght be a cofactor in the pathogenicity of MAC.