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pubmed:abstractText |
n-Acyl homoserine lactones (AHLs) are produced by gram-negative bacteria to regulate gene expression in a cell density dependent manner. For instance, expression of virulence factors by pathogens such as Pseudomonas aeruginosa is induced only when a threshold concentration of AHLs is reached, which indicates that the bacterial population is big enough to promote infection. In this study, the indicator strain Agrobacterium tumefaciens NTL4 (pZLR4), which carries a ?-galactosidase (?-gal) reporter gene under the control of a quorum sensing promoter, was used to develop an electrochemical biosensor to detect AHLs using the model n-(3-oxo)-dodecanoyl-L-homoserine lactone (oxo-C12-HSL), an AHL previously detected in cystic fibrosis patients infected with P. aeruginosa. The substrate 4-aminophenyl ?-D-galactopyranoside was used to detect ?-gal activity by cyclic voltammetry. Furthermore, simultaneous monitoring of substrate consumption and p-aminophenol production by ?-gal allowed on-chip result verification by dual-signal confirmation. The sensor exhibited high reproducibility and accurately detected oxo-C12-HSL in a low picomolar to low nanomolar range in spiked liquid cultures and artificial saliva, as well as AHLs naturally released by P. aeruginosa in culture supernatants. Moreover, detection took just 2 h, required no sample pretreatment or preconcentration steps, and was easier and faster than traditional methods.
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pubmed:affiliation |
Institut de Microelectro?nica de Barcelona (IMB-CNM), CSIC, Campus UAB, 08193 Bellaterra, Barcelona, Spain. eva.baldrich@imb-cnm.csic.es
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