title: An unconventional approach to impedance microbiology: detection of culture media conductivity variations due to bacteriophage generated lyses of host bacteria.
abstract: A novel and unconventional approach to impedance microbiology has been under investigation. In our approach, solution conductivity variations are generated from bacteriophage lyses of infected host cells and the consequent release of conductive endoplasmic material. To sensitively detect the lysis, low conductive growth media have been developed. A microchip has been fabricated to perform the analysis. The microchip is made of two bare gold electrodes and PDMS microchamber of 36 nL volume. Escherichia coli and selective phages T4 have been used as case study. Proof-of-principle experiments are here presented and discussed. The method was characterised in a wide range between 10(4) and 10(8) CFU/mL, where linear relation was found between conductivity variation and cell concentration in a log10 vs. log10 plot. The method is suited to integration with sample preparation based on phage-functionalised magnetic beads. It has a potential detection limit below 1 CFU/chamber and a total assay time of less than 1 h.
authors.affiliation: Microsystems Technology Research Unit, Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, Povo 38123, Trento, Italy. Electronic address: Mortari@fbk.eu.
authors.forename: Alessia
authors.initials: A
authors.lastname: Mortari
authors.affiliation: Microsystems Technology Research Unit, Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, Povo 38123, Trento, Italy. Electronic address: andadami@fbk.eu.
authors.forename: Andrea
authors.initials: A
authors.lastname: Adami
authors.affiliation: Microsystems Technology Research Unit, Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, Povo 38123, Trento, Italy. Electronic address: lorenzel@fbk.eu.
authors.forename: Leandro
authors.initials: L
authors.lastname: Lorenzelli
mesh_terms: D017122:Bacteriophage T4 / Q000254:growth & development / Q000302:isolation & purification*; D015374:Biosensing Techniques; D003470:Culture Media / Q000032:analysis* / Q000737:chemistry; D004553:Electric Conductivity; D017097:Electric Impedance; D004926:Escherichia coli / Q000302:isolation & purification* / Q000821:virology; D006046:Gold / Q000737:chemistry; D046208:Microchip Analytical Procedures
chemical_list: D003470:Culture Media; D006046:Gold
keywords: Bacteriophage; Impedance microbiology; Low conductivity broth; Microsystem; Pathogen detection; System integration