FIG. 2.

Comparison of bldM alleles in different genetic backgrounds. The strains were grown on R2YE solid medium at 30°C for 4 days. A bldM::hyg allele was previously introduced into the J1915 genetic background to obtain bald strain J2151, which is blocked for aerial mycelium formation (27). Transfer of the bldM::hyg allele to M145 by genomic transformation yielded strain DB2321, which produces an aerial mycelium but fails to sporulate. Strain DB2571, which bears a bldM::Tn5apr allele and was generated in the M145 genetic background, also produces a nonsporulating aerial mycelium.