Pigments and antibiogram of transconjugants from nonpigmented mutants of Serratia marcescens.

ABSTRACT

Serratia marcescens produces a characteristic red pigment, prodigiosin, which is formed by the enzymatic coupling of 4-methoxy-2,2'-bipyrrole-5-bipyrrole-5-carboxaldehyde (MBC) and 2-methyl-3-amylpyrrole (MAP). Many clinical isolates which are resistant to multiple antibiotics are nonpigmented. However, the relationship of pigmentation (or nonpigmentation) to drug resistance of the strains has not yet been established. In this study we demonstrated the pigment synthesizing capability in the transconjugants obtained from nonpigmented mutants WF and 9-3-3 of S. marcescens under the condition of cell-to-cell contact. Mutant WF produces MAP while mutant 9-3-3 synthesized only MBC. After genetic transfer, the color of the recombinant colonies was red indicating the successful transfer of the pigment synthesizing capability. The antibiogram of the transconjugants indicated that they inherited the resistance characteristics to polymyxin B and chloramphenicol from their parent strains. further supportive evidence was obtained by spectroscopic and high performance liquid chromatographic analysis of the resulting pigments extracted from the pigmented transconjugants. The pigments produced by the transconjugants were similar, if not identical, to those produced by the wild type strain 08 and those synthesizes syntrophically. The possibility of simultaneous transfer of pigment synthesizing capability and drug resistance remains to be explored .