Phenotypic Comparison of Wild-Type and Mutant Strains of Streptomyces coelicolor

Begin with cultures of wild-type and mutant strains of Streptomyces coelicolor, a filamentous soil bacterium.

The mutant strains carry mutations in developmental genes that cause phenotypic differences from the wild type.

Reculture the colonies onto fresh plates to minimize the accumulation of spontaneous mutations with age.

Streak single colonies of the strains onto separate regions of a plate in a wedge pattern to avoid cross-contamination

Incubate the plate to promote bacterial growth.

Wild-type strains form aerial filaments that develop into long chains of gray-pigmented spores, giving the colonies a fuzzy appearance.

In contrast, mutant strains either fail to develop aerial filaments, resulting in a bald appearance, or produce fewer pigmented spores, causing the aerial filaments to appear white.

Place the Petri dish on a uniform background to visualize colony morphology.

Capture images to visually compare the phenotypic differences between the wild-type and mutant strains.

Use a standard method, such as the quadrant streak method demonstrated in Saunders 2012 to streak Streptomyces strains onto MS agar plates and culture into single colonies.

Every four to six days, pick a single colony