The influence of age of culture on the production of adjuvant-active peptidoglycolipids by saprophytic mycobacteria

Abstract

Wax D fractions obtained from young cultures (7 day) of Mycobacterium phlei and Mycobacterium smegmatis were found to contain more peptidoglycolipid, than those from old (28-day) cultures. The wax closely resembled Wax D from human strains of mycobacteria. These peptidoglycolipid fractions acted as adjuvants, producing a local granuloma at the site of injection, increasing the size of homolateral lymph nodes, inducing a delayed-type hypersensitivity (corneal response) against ovalbumin and increasing serum anti-ovalbumin precipitin levels. With extended periods of cultivation (4–6 weeks) the amount of extractable peptidoglycolipid from saprophytic organisms decreased until finally only adjuvant-inactive Wax D (glycolipid) preparations were obtained.

The hydrosoluble moiety of the peptidoglycolipid contains those amino acids, hexosamines and sugars that are found in the mucopeptide of the bacterial cell wall. It is suggested that in the absence of nutrient in the culture medium, mycobacterial growth is maintained by autonutrition from the peptidoglycolipid.