Scanning electron microscopy analysis of aged Mycobacterium tuberculosis cells.

Most electron microscopy studies of Mycobacterium tuberculosis ultrastructure were performed in the 1950s and 1960s and lack high resolution by modern standards. This study was performed to re-evaluate the fine structure of M. tuberculosis using modern scanning electron microscopy. Bacteria were grown in rich medium with a constant supply of oxygen for several weeks. Results show that surface bleb-like structures accumulate as cultures age. The most unusual feature of aging M. tuberculosis cultures is that they develop extracellular fibrils, which could play roles of adhering cells to surfaces and to one another.