title: A novel approach to improve specificity of algal biosensors using wild-type and resistant mutants: an application to detect TNT.
abstract: A new genetic approach was developed for increasing specificity of microalgal biosensors. This method is based on the use of two different genotypes jointly to detect a given pollutant: (i) a sensitive genotype to obtain sensitivity; and (ii) a resistant mutant to obtain specificity. The method was tested by the development of a microalgal biosensor for the detection of the explosive 2,4,6-trinitrotoluene (TNT) using a wild-type strain (DcG1wt) of Dictyosphaerium chlorelloides (Chlorophyceae) as the sensitive organism, and a TNT-resistant mutant, obtained from DcG1wt strain by a modified Luria-Delbrück fluctuation analysis. The inhibition of chlorophyll a fluorescence of PSII by TNT was used as the biological signal. Significant differences in maximal fluorescence of light-adapted algae (F'(m)) between wild-type DcG1wt cells and TNT-resistant mutants, were observed in all the TNT concentrations tested (from 0.5 to 31.3 mg l(-1)) after only 3 min of exposure. Resistant mutants always exhibited significant higher F'(m) values in the presence of TNT than wild-type cells. These results suggest that the use of two different genotypes (sensitive and resistant to a given pollutant) jointly is a useful method to improve microalgal biosensors specificity.
authors.affiliation: Departamento de Biología Vegetal (Botánica), Facultad de Ciencias, Universidad de Málaga, E-29071 Málaga, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Altamirano
authors.forename: Libertad
authors.initials: L
authors.lastname: García-Villada
authors.forename: Mar
authors.initials: M
authors.lastname: Agrelo
authors.forename: Laura
authors.initials: L
authors.lastname: Sánchez-Martín
authors.forename: Luis
authors.initials: L
authors.lastname: Martín-Otero
authors.forename: Antonio
authors.initials: A
authors.lastname: Flores-Moya
authors.forename: Marcos
authors.initials: M
authors.lastname: Rico
authors.forename: Victoria
authors.initials: V
authors.lastname: López-Rodas
authors.forename: Eduardo
authors.initials: E
authors.lastname: Costas
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D056890:Eukaryota / Q000235:genetics; D009154:Mutation; D014303:Trinitrotoluene / Q000032:analysis*
chemical_list: D014303:Trinitrotoluene