The physiology and pathogenicity of Mycobacterium tuberculosis grown undercontrolled conditions in a defined medium

A chemically-defined culture medium was developed which supported batch gro wth of Mycobacterium tuberculosis, strain H37Rv, at a minimum doubling time of 14.7 h. This medium also facilitated chemostat culture of M. tuberculos is at a constant doubling time of 24 h. Chemostat growth was optimized at a dissolved oxygen tension of 20% (v/v) and 0.2% (v/v) Tween-80. Chemostat c ultures were dispersed suspensions of single bacilli (1.5-3 mu m long), or small aggregates, at a mean density of log(10) 8.3 cfu ml(-1). A limited nu mber of amino acids was utilized (alanine, asparagine, aspartate and serine were depleted by > 50%; glycine, arginine, isoleucine, leucine and phenyla lanine, by approximately 40%). Chemostat-grown cells were pathogenic in aer osol-infected guinea pigs, producing disseminated infection similar to that caused by plate-grown cells. Cells from chemostat culture were significant ly more invasive for J774A.1 mouse macrophages than agar- or batch-grown ce lls. This study demonstrates the suitability of chemostat culture for the g rowth of pathogenic mycobacteria in a defined physiological state with pote ntial applications for the controlled production of mycobacterial component s for therapeutic and vaccine applications.