title: Growth depression of Serratia marcescens by plasmids that belong to incompatibility group P.
abstract: The IncP plasmids R702, RP4 and derivative plasmids including RP4::Mu cts were studied in two pigmented strains of Serratia marcescens. Maintenance of these plasmids resulted in reduced pigmentation and the growth rate of colonies was slower than the plasmid-free parent organisms. DNA inserts and deletions in RP4 altered both the pigmentation phenotype and growth rate of S. marcescens transconjugants and was inversely related to the change in molecular weight. The unrelated plasmids R446b and R46, although of comparable size to RP4, produced neither effect and Rts1, more than three times larger than RP4, produced no visible change in pigmentation phenotype and only a minimal decrease in growth rate. Integration of RP4::Mu cts into the Serratia genome restored pigmentation and growth rate to the same level as the plasmid-free parent. Partial induction at 43 degrees C restored the plasmid to a cytoplasmic state in a proportion of surviving colonies which were typically pale and slow growing.
authors.affiliation: Department of Bacteriology, University of Glasgow, Royal Infirmary, Scotland, Great Britain.
authors.forename: D J
authors.initials: DJ
authors.lastname: Platt
authors.forename: J S
authors.initials: JS
authors.lastname: Chesham
mesh_terms: D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry; D006801:Humans; D008970:Molecular Weight; D010641:Phenotype; D010858:Pigmentation / Q000235:genetics*; D011815:R Factors; D012706:Serratia marcescens / Q000235:genetics / Q000254:growth & development*
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial