SPONTANEOUS AND INDUCED COLOR-VARIATION OF THE HY STRAIN OF SERRATIA MARCESCENS

Abstract

Two color-variants were produced by red cultures of the HY strain of S. marcescens. Stable dark red, pink or white types occurr rarely as spontaneous variants but are induced readily by u.-v. irradiation. Photoreactivation with white light reverses the mutational as well as lethal effects of the u.-v. light. The incidence of color-variants is not increased by treatments with a wide variety of chemical agents. An unstable colorless types with very different characteristics was found in all pigmented cultures. It produces speckled colonies on synthetic but not on peptone agar. U.-v. irradiation has no apparent effect on the incidence of these common variants but cultural conditions greatly influence their numbers.