WF11899A

In the course of screening for antifungal antibiotics, we have discovered a novel series of lipopeptide compounds structurally related to, but highly superior to, echinocandin B in terms of their water solubility due to the presence of a sulfate residue. These compounds, WF11899s, WF738s, WF14573s, WF16616 and WF22210, and their derivatives have diversity in their nuclear structures and acyl side chains. The producing strains were classified into two groups, the Coleomycetes group and the Hyphomycetes group. Compound FK463, a derivative of WF11899A, is currently in Phase 3 clinical development as a novel antifungal antibiotic.

FR901379 (WF11899A) is a novel echinocandin type of lipopeptide antibiotic produced by Coleophoma empetri F-11899. Micafungin (FK463) is derived from the chemical modification of deacylated FR901379. In the present paper, we performed seven generation's strain-breeding, beginning with a wild type, was performed. Selection medium for screening and production medium for high FR901379 production were designed. Sodium chloride content in the selection plate was affected to FR901379 production and shrinkage of the colony size was observed in high producing strains. As selection markers, large colony-shrinking rate and large inhibition circle in the agar-piece method using C. albicans was selected. Using CMA medium with high sodium chloride, 3 mutants, M-1 to M-3, have achieved a high FR901379 production and M-3 showed 5.0 U/mL, while 1.0 U/mL of production was achieved in wild type strain. A-2 medium supplemented with 6% of soluble starch as a carbon source and 0.6% of ammonium sulfate as nitrogen source was also further effective for mutant screening. The FR901379 production of mutant M-4 (fourth generation) increased until 16.0 U/mL. The concentration of the phosphate salt in the medium seemed to inhibit the growth so as to extend the culture period. When the A-3 medium supplemented with low concentration of phosphate salt and magnesium sulfate as a sulfate source was designed and used, mutants with improved production were successively obtained. Finally, variant strain M-7 showed 30.0 U/mL of production, which was about 30 times higher than that of the wild strain.

Industrial-scale production of FR901379 (WF11899A), which is a novel echinocandin type of lipopeptide antibiotic produced by mutant strain M-7 from Coleophoma empetri F-11899 (FERM BP-2635), was demonstrated. In order to achieve high-level production in fermentor culture, the medium previously developed was modified, in which three types of organic nitrogen were replaced by ammonium sulfate and corn steep liquor. To eliminate increase in viscosity, carbon source was intermittently fed. The viscosity was reduced from 20,000 cP to less than 10,000 cP. The FULLZONE impeller was introduced in the fermentor culture for sufficient mixing. Mixing time was quite improved and high reproducibility was achieved. Surprisingly, the viscosity of the broth was reduced to 1000 cP in a 4 m(3) scale fermentor. When k(L)a was selected as an index for scale-up and industrial scale production using a 15 m(3) fermentor with the FULLZONE impeller was conducted, FR901379 production was successfully obtained at more than 50 U/mL, almost the same level as with the 0.03 m(3) and 4 m(3) fermentors. In addition, superior reproducibility was obtained, and 500-fold scale-up was successfully achieved.