The use of health-relevant bacteria originating from human microbiomes for the control or therapy of diseases including neurodegenerative disorders or diabetes is currently arising as the next “big thing” in medicine. Directed and fruitful engineering of microbiomes by probiotic supplementation will require a subtle, precise and – probably even more important – easy, fast and convenient monitoring of its success e.g. in the patients’ gut. Based on a previously described polyclonal SELEX aptamer library evolved against the human gut bacterium Blautia producta, we have finally isolated three individual aptamers, which proofed their performance concerning affinity, specificity and robustness in labeling the target bacterium reliably also in mixtures with “contaminating” control bacteria. Used as biofunctionalization molecules on gFETs we could specifically quantify from 101 – 106 cells/mL, could retrace their number in mixtures and determined the aptamer Kd-values around 2 nM. These measurements were possible even in the background of real human stool sample. Our results qualify gFETs in combination with these aptamers BL2, BL7 and BL8 as promising foundation for the construction of respective sensing devices, which then will open new avenues towards the intended monitoring technique for probiotic therapy and microbiome engineering approaches.
