FIG. 5.

Cross-feeding relationship of thn structural mutants. Cosynthesis experiments were performed with thnN, thnL, thnO, and thnP non-thienamycin-producing structural mutants. Agar strips from R5A (minus sucrose) agar plates containing the mutants grown for 6 to 10 days at 28°C were used in the bioassays against thienamycin-sensitive S. aureus strain ATCC 6538P. The inhibition zones indicate a restoration of thienamycin biosynthesis due to the diffusional exchange of accumulated intermediates. No cross-feeding was detectable in the rest of the pairs. The wild-type strain was used as a positive control. L, N, O, and P indicate mutants generated in genes thnL, thnN, thnO, and thnP.