FIG. 3.

Phenotypes of mutants MK1 and MK2. (A) Schematic representation of the arpA region on the chromosomes of mutants MK1 and MK2. Mutant MK1 contains both the intact arpA and the mutated arpA (Trp119Ala) in addition to the kanamycin resistance gene. (B) Effects of the arpA W119A mutation on morphological differentiation. S. griseus IFO13350 (wild type, wt), MK1, and MK2 were grown on YMPD agar medium at 28°C for 3 days. Neither MK1 nor MK2 formed aerial hyphae or spores. Introduction of pADP20L containing the adpA-coding sequence under the control of the E. coli lac promoter resulted in restoration of sporulation in MK2, whereas pADP10L, containing the intact adpA, did not restore the defect in aerial hypha formation of MK2. (C) Effects of the Trp119Ala mutation on streptomycin production. Strains were grown on Bennett agar medium without glucose at 28°C for 3 days, as described in the legend toFig. 1. (D) Effects of the Trp119Ala mutation on grixazone production. Strains were grown on phosphate-depleted standard minimal medium at 28°C for 3 days, as described previously (31). Grixazone is produced only on phosphate-depleted medium. (E) Scanning electron micrographs of spores formed by S. griseus IFO13350 and mutant MK2 harboring pADP20L. Both strains were grown on R2YE agar medium (10) at 28°C for 3 days. Bar, 2 μm.