In the present study, a new possibility for an absorptiometric microbial biosensor principle involving a modified Trinder’s reaction and a lipophilic mediator’s reaction is proposed. In the modified Trinder’s reaction, peroxidase is used as a catalyst for the coupling of phenolic hydrogen donor (MAOS) and 4-aminoantipyrine (4-AA) in the presence of hydrogen peroxide as an oxidant. In this study, hexacyanoferrate(III) [HCF(III)] was used in the modified Trinder’s reaction as an alternative to the peroxidase and hydrogen peroxide, and then a blue-colored MAOS-4AA complex (λmax = 630 nm) was produced. The blue-colored solution containing the MAOS-4AA complex was reacted with a mixture, which contained living yeast cells, menadione (lipophilic mediator), and glucose-glutamic acid (GGA) solution. Then, an absorbance decrease was observed by increasing the GGA concentration. To confirm the measurement principle, potassium HCF(III) was added to the supernatant of the measurement solution, and then the supernatant developed a blue color again at the same absorbance as the measurement solution. It was shown that the MAOS-4AA complex was formed repeatedly using the proposed principle. This shows another possibility of MAOS and 4-AA as reusable reagents. Finally, linear responses between 55 and 220 mg O2 L-1 GGA were obtained after sample preparation, which took a total of 15 min (10 min incubation for GGA assimilation and a subsequent 5 min incubation for the decoloration of the modified Trinder’s reagent). The lower limit of detection was calculated to be at around 17 mg O2 L-1 GGA under conditions of 1 mM or 2 mM HCF(III).
Buy this Article