Selective action of mycobacillin on the uptake of releasable cell materials by Aspergillus niger.

The uptake of normally releasable (i.e. releasable in the absence of the antibiotic) cell constituents (namely lysine, proline, ATP, Pi, Na+, K+ and Ca2+) by sensitive cells of Aspergillus niger that occurs in the absence of mycobacillin is gradually enhanced with increase in concentration of the antibiotic until the uptake attains the maximum. With still higher concentrations the uptake decreases until it becomes the same as in the control without mycobacillin. Uptake follows saturation kinetics both in the absence and in the presence of the antibiotic. Mycobacillin significantly increases Vmax. for uptake with any effect on Km, Mycobacillin has no action on the uptake of non-releasable materials.