title: Influence of S9 mix on the expression of mutants in the L-arabinose resistance test of Salmonella typhimurium.
abstract: S9 mix produces an effect similar to that of D-glucose in the L-arabinose resistance test of Salmonella typhimurium, releasing the growth inhibition exerted by L-arabinose. Two elements are responsible for this effect: the glucose-6-phosphate present in the cofactors of the S9 mix and the S9 fraction itself. UV light was used as a mutagen to compare the efficiency of S9 mix and D-glucose in allowing phenotypic expression of mutants in selective plates with L-arabinose; 0.5 ml of S9 mix per plate showed and efficacy similar to that of 0.5 mg of D-glucose per plate. To verify that the S9 mix is equivalent to D-glucose traces in selective plates with respect to the number of induced mutants in compounds requiring metabolic activation, we utilized 2 direct-acting nitrofurans. Our conclusion is that activation of agents could be erroneously attributed to the S9 mix, when plates with 0.5 mg of D-glucose are compared to plates with 0.5 ml of S9 mix plus 0.5 mg of D-glucose. Our results suggest that D-glucose traces be omitted in experiments requiring the presence of the S9 mixture.
authors.affiliation: Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Spain.
authors.forename: T
authors.initials: T
authors.lastname: Roldán-Arjona
authors.forename: M
authors.initials: M
authors.lastname: Ruiz-Rubio
authors.forename: C
authors.initials: C
authors.lastname: Pueyo
mesh_terms: D000818:Animals; D001089:Arabinose / Q000494:pharmacology*; D003470:Culture Media / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D015870:Gene Expression; D005947:Glucose / Q000494:pharmacology; D008099:Liver / Q000201:enzymology; D009152:Mutagenicity Tests; D009153:Mutagens / Q000378:metabolism*; D009154:Mutation; D051381:Rats; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics*; D014466:Ultraviolet Rays
chemical_list: D003470:Culture Media; D009153:Mutagens; D001089:Arabinose; D005947:Glucose