title: Growth characteristics of V factor-independent transformants of Haemophilus influenzae.
abstract: Haemophilus influenzae is a V factor-dependent species. A plasmid conferring V factor independence in Haemophilus parainfluenzae and Haemophilus ducreyi was transferred to plasmid-free H. influenzae Rd by DNA transformation. The growth characteristics of the transformants in a complex and a chemically defined medium were compared, and the ability of several exogenous pyridine nucleotides and precursors to support growth was examined. Although the transformants appeared to be V factor independent in a complex medium, in a chemically defined medium they exhibited both V factor-dependent and nicotinamide-dependent growth. Because of the inability of the plasmid-free H. influenzae Rd to utilize nicotinamide for growth, it was concluded that the genes conferring this function were plasmid linked. Our results indicate that the V factor requirement, as it is presently defined, is not suitable to serve as a definitive taxonomic criterion for species determination in the family Pasteurellaceae.
authors.affiliation: Emergent Pathogen Research Unit, South African Medical Research Council, School of Pathology, University of the Witwatersrand, Johannesburg.
authors.forename: H M
authors.initials: HM
authors.lastname: Windsor
authors.forename: R C
authors.initials: RC
authors.lastname: Gromkova
authors.forename: H J
authors.initials: HJ
authors.lastname: Koornhof
mesh_terms: D002455:Cell Division; D006133:Growth Substances / Q000378:metabolism; D006190:Haemophilus / Q000235:genetics; D006191:Haemophilus ducreyi / Q000235:genetics; D006193:Haemophilus influenzae / Q000235:genetics* / Q000254:growth & development*; D009243:NAD / Q000378:metabolism*; D015661:Pasteurellaceae / Q000145:classification; D010957:Plasmids / Q000235:genetics*; D014170:Transformation, Genetic
chemical_list: D006133:Growth Substances; D009243:NAD