title: Luminometric Label Array for Counting and Differentiation of Bacteria.
abstract: Methods for simple and fast detection and differentiation of bacterial species are required, for instance, in medicine, water quality monitoring, and the food industry. Here, we have developed a novel label array method for the counting and differentiation of bacterial species. This method is based on the nonspecific interactions of multiple unstable lanthanide chelates and selected chemicals within the sample leading to a luminescence signal profile that is unique to the bacterial species. It is simple, cost-effective, and/or user-friendly compared to many existing methods, such as plate counts on selective media, automatic (hemocytometer-based) cell counters, flow cytometry, and polymerase chain reaction (PCR)-based methods for identification. The performance of the method was demonstrated with nine single strains of bacteria in pure culture. The limit of detection for counting was below 1000 bacteria per mL, with an average coefficient of variation of 10% achieved with the developed label array. A predictive model was trained with the measured luminescence signals and its ability to differentiate all tested bacterial species from each other, including members of the same genus Bacillus licheniformis and Bacillus subtilis, was confirmed via leave-one-out cross-validation. The suitability of the method for analysis of mixtures of bacterial species was shown with ternary mixtures of Bacillus licheniformis, Escherichia coli JM109, and Lactobacillus reuteri ATCC PTA 4659. The potential future application of the method could be monitoring for contamination in pure cultures; analysis of mixed bacterial cultures, where examining one species in the presence of another could inform industrial microbial processes; and the analysis of bacterial biofilms, where nonspecific methods based on physical and chemical characteristics are required instead of methods specific to individual bacterial species.
authors.affiliation: Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku , Kiinamyllynkatu 10, FI-20520 Turku, Finland.
authors.forename: Milla
authors.initials: M
authors.lastname: Högmander
authors.affiliation: Applied Microbiology, Department of Chemistry, Lund University , P.O. Box 124, SE-22100 Lund, Sweden.|Water Resources Engineering, Department of Building and Environmental Engineering, Lund University , P.O. Box 118, SE-22100 Lund, Sweden.
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Paul
authors.affiliation: Applied Microbiology, Department of Chemistry, Lund University , P.O. Box 124, SE-22100 Lund, Sweden.|Sweden Water Research, Ideon Science Park , Scheelevägen 15, SE-22370 Lund, Sweden.
authors.forename: Sandy
authors.initials: S
authors.lastname: Chan
authors.affiliation: Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku , Kiinamyllynkatu 10, FI-20520 Turku, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Hokkanen
authors.affiliation: Laboratory of Materials Chemistry and Chemical Analysis, Department of Chemistry, University of Turku , Vatselankatu 2, FI-20500 Turku, Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Eskonen
authors.affiliation: Department of Information Technology, University of Turku , Vesilinnantie 5, FI-20500 Turku, Finland.
authors.forename: Tapio
authors.initials: T
authors.lastname: Pahikkala
authors.affiliation: Department of Cell Biology and Anatomy, Institute of Biomedicine, University of Turku , Kiinamyllynkatu 10, FI-20520 Turku, Finland.|Applied Microbiology, Department of Chemistry, Lund University , P.O. Box 124, SE-22100 Lund, Sweden.|Laboratory of Materials Chemistry and Chemical Analysis, Department of Chemistry, University of Turku , Vatselankatu 2, FI-20500 Turku, Finland.
authors.forename: Sari
authors.identifier: 0000-0002-2411-6724
authors.initials: S
authors.lastname: Pihlasalo
mesh_terms: D001407:Bacillus / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D001419:Bacteria / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D056831:Coordination Complexes / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D005063:Europium / Q000737:chemistry; D005434:Flow Cytometry / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry*; D025341:Principal Component Analysis
chemical_list: D056831:Coordination Complexes; D005456:Fluorescent Dyes; D005063:Europium