title: Isolation of sensitive nisin-sensing GFP(uv) bioassay Lactococcus lactis strains using FACS.
abstract: Fluorescence-activated cell sorting (FACS) was used to isolate mutants of Lactococcus lactis LAC275, an indicator strain in GFP(uv) nisin bioassay. It harbors the GFP(uv) encoding gene under the nisA promoter and the nisin signal transduction nisRK genes whereby nisin concentration can be correlated to GFP(uv) fluorescence. The sorted L. lactis cells, which showed higher fluorescence intensities at low inducer concentration, were analysed for higher responsiveness to low concentration of nisin. Two strains showed lower detection limits (0.2 pg ml(-1)) for nisin than the parent strain (10 pg ml(-1)). This showed that mutants of LAC275 could successfully be isolated using FACS.
authors.affiliation: Department of Applied Chemistry and Microbiology, University of Helsinki, P.O. Box 56, FI-00014, Helsinki, Finland.
authors.forename: Hanan T Abbas
authors.initials: HT
authors.lastname: Hilmi
authors.forename: Kaisa
authors.initials: K
authors.lastname: Hakkila
authors.forename: Per E J
authors.initials: PE
authors.lastname: Saris
mesh_terms: D001681:Biological Assay; D015374:Biosensing Techniques; D005434:Flow Cytometry / Q000379:methods*; D005453:Fluorescence; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D013294:Lactococcus lactis / Q000302:isolation & purification*; D009561:Nisin / Q000378:metabolism*
chemical_list: D009561:Nisin; D049452:Green Fluorescent Proteins