Performance assessment of the two oxygen sensor based respirometric platforms with complex media and in selective bacterial assays

• Published in: Sensors and actuators. B, Chemical Chemical, 2023-05, Vol.383, p.133582, Article 133582
• Main Authors: Elisseeva, Sophia, Santovito, Elisa, Linehan, Eva, Kerry, Joseph P., Papkovsky, Dmitri B.
• Format: Article
• Language: English
• Subjects: Bacterial cell respiration; Determination of bacteria; Optical oxygen respirometry; Quenched-phosphorescence oxygen sensing; Selective assays
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2023.133582

Two common platforms currently used in respirometric microbial assays were evaluated comparatively with a panel of selective and differential media specific for E. coli, including the MacConkey (MC), M-Lauryl Sulfate (MLS), Minerals Modified Glutamate (MMG) and Rapid Coliform ChromoSelect (RCC) broths. The first automated platform is based on a soluble O2 probe MitoXpress, standard microwell plate substrate and time-resolved fluorescence reader detection. While operating stably in MC and MMG, it showed prominent interferences and instability in RCC and MLS media, due to phenol red dye and the surfactant largely attenuating the probe signal. The second platform, based on the longwave emitting solid-state sensor coatings deposited at the bottom of disposable assay vials and read with a handheld sensor reader Piccolo2. While having lower sample throughput and automation, this platform demonstrated stable operation in all the media, because its sensor dye PtBP is effectively shielded from interference by sample and media components making the assays stable and robust. Calibration functions for E.coli enumeration show linear relationship with measured Threshold Time (TT, hours): Log (CFU/mL) = a - b*TT, with a ranging 7.24–7.73 h-1 and b ranging 0.49–0.77 for the different selective media. These results help to choose the optimal respirometry platform for large-scale applications such as selective microbial assays and culturomics. •The two biosensor based respirometric platforms were assessed with ‘nasty’ samples and complex growth media•The MitoXpress platform with liquid O2 probe was prone to optical and chemical interferences by media components•The Sensor Vial platform with solid-state O2 sensor coatings showed stable and robust operation in all tested conditions•The results help to choose optimal platform for large-scale applications - selective microbial assays and culturomics