Synthesis and release of sulfolipid by Mycobacterium avium during growth andcell division.

Mycobacterium avium exhibits a life cycle wherein small cells elongate to form filaments. The life cycle is unique in that elongated cells will undergo rapid division by fragmentation only if fatty acid is present. The utilization of [14C]palmitic acid and [3H]oleic acid by M. avium during the life cycle was assessed. Four glycolipids, identifiable by elution patterns from hydroxylapatite columns, were associated with postfission cells and contained isotope from the precursor fatty acid. The incorporation of 3H from oleic acid into the cellular glycolipids was maximal during cell division, but as much as 73% of the radioactivity was lost to the lipids from cells in the postfission status. Three of the glycolipids were sulfatides into which 36S was incorporated by M. avium. The [35]sulfatides were synthesized by cells undergoing fragmentation and were recovered from the medium at the termination of cell fission. These results demonstrated that the isotope was not lost to the cells because of turnover, but rather that the labeled compounds were released, intact, from the cells after fission. Because of the facile release of the sulfolipids, it was suggested that they were part of the cell envelope of M. avium cells during the division process.