USE OF ARTHROBACTER TERREGENS FOR BIOASSAY OF MYCOBACTIN.

Reich, Claude V. (Johns Hopkins-Leonard Wood Memorial Leprosy Research Laboratory, Johns Hopkins University, Baltimore, Md.), and John H. Hanks. Use of Arthrobacter terregens for bioassay of mycobactin. J. Bacteriol. 87:1317-1320. 1964.-Arthrobacter terregens was used to assay mycobactin, a growth factor for Mycobacterium paratuberculosis. Within 7 days, A. terregens gave a linear photometric growth response to mycobactin in the range of 0.05 to 0.2 mug/ml. Preparations found to be active (or inactive) by this assay produced corresponding effects on the growth of M. paratuberculosis after 6 weeks to 4 months. Mycobactin was produced routinely from pellicles of M. phlei on a peptone-glycerol-beef heart infusion medium, and was extracted from both cells and medium by organic solvents. The mycobactin content per cell rose rapidly after the third day and attained a maximum at 4 to 6 days. The decline to less than one-half this value by the tenth day was associated with excretion into the medium. Production on synthetic media occurred after increasing the usual levels of asparagine. The demonstrated effects of crude mycobactin on the donor strain were (i) to catalyze the onset of growth and (ii) to reverse the effect of conditions which cause the formation of abnormal cells.