Improved monitoring of P. aeruginosa on agar plates

Abstract

Described is the fabrication of a disposable electrochemical assay that is integrated with standard King's A agar culture plates, for the selective and specific detection of Pseudomonas aeruginosa. Agar plates provide several advantages over liquid culture, including protecting the sensor from biofouling and faster identification in small sample volumes. Cultures of P. aeruginosa, starting from initial cell counts of 10 2 to 10 8 cells in 5 microliter volumes, were incubated at 23, 37, and 42 C and monitored both visually and electrochemically. Square wave voltammetry scans confirmed the production of a redox species, pyocyanin, over time that was dependent on the initial load of cells. The pyocyanin easily diffuses through the agar to reach the electrode surface. Using this simple and cheap approach, positive identification of P. aeruginosa was achieved several hours faster via electrochemical detection compared to traditional visual analysis. † Electronic supplementary information (ESI) available: ESI contains a calibration curve for PYO measured in TSB media, solid TSB agar, and solid King's A agar; a plot of the measured maximum current vs. time for the bacterial loads used in Fig. 4; curves from which the maximum PYO production rate in Fig. 2B was calculated; and scanning electron microscopy images of P. aeruginosa grown on King's A agar as well as the surface of the electrodes aer cell growth. See

Bioelectronic Platform to Investigate Charge Transfer between Photoexcited Quantum Dots and Microbial Outer Membranes

“…To quantify the fraction of the SLB surface involved in the electrochemical interaction with the electrolyte, we calculated the ECSA via the Randles–Ševčík relation , which describes the relationship between peak current ( I p ), pyocyanin concentration ( C ), pyocyanin diffusion coefficient ( D ), number of electrons in pyocyanin redox ( n ), Faraday’s constant ( F ), CV scan rate ( v ), temperature ( T ), and the universal gas constant ( R ). Peak oxidation currents were experimentally measured in our CV scan and the pyocyanin diffusion coefficient in bulk aqueous media was assumed to be 2.5–10 –9 m 2 /s based on literature reports. − For all experiments, a linear relationship between peak oxidation current and the square root of CV scan rate was observed, verifying the validity of using the Randles–Ševčík equation to analyze SLBs within our bioelectronic platform; these data are shown in Figure S15.…”

Electrochemical camera chip for simultaneous imaging of multiple metabolites in biofilms

“…Electrochemical techniques are an attractive choice for detecting phenazines due to their strong redox activity, and the use of this electrochemical activity for detection and quantification could be applied to many metabolites in addition to phenazines. Electrochemical detection of phenazines has been demonstrated in liquid cultures of P. aeruginosa 20 21 22 23 24 25 and in biofilms 26 , though the latter study did not attempt detection with spatial resolution. SECM has been used for spatially resolved detection of phenazines in P. aeruginosa biofilms 27 and aggregates 28 .…”

Molecular Signature of Pseudomonas aeruginosa with Simultaneous Nanomolar Detection of Quorum Sensing Signaling Molecules at a Boron-Doped Diamond Electrode

“…Adsorptive stripping voltammetry (AdSV) using a hanging mercury drop electrode (HMDE) 17 and differential pulse voltammetry (DPV) using graphite rods 18 were employed for PYO detection in biological samples. Disposable screen-printed electrodes were also used to probe the presence of PYO in the human biofluids by square wave voltammetry (SWV) 19 20 21 . Sismaet et al .…”