Effects of ultraviolet-absorbing compounds on spore germination and cultural variation in microorganisms.

A brightener and a nonfluorescent ultraviolet absorber were found to be associated with an increase in the per cent of spore germination and cultural variation in a streptomycete and a Penicillium. When the brightener was combined with ultraviolet light, more variants were obtained than with either ultraviolet or brightener alone. This effect occurred at concentrations of brightener substantially greater than those used for fluorescent labeling.