A bio-selective membrane electrode prepared with living bacterial cells.

A novel potentiometric sensor has been devised by coupling intact microorganisms (Streptococcus faecium) with an ammonia gas-sensing membrane electrode. The resulting electrode provides a linear response to arginine over the concentration range 5.0 × lO^-5–1. 0 × 10^-3 M in phosphate buffer pH 7.4, with selectivity over other amino acids. The slope of the calibration graph is -40 to -45 mV/decade during the period 2–20 days after preparation. This membrane electrode with living bacterial cells may serve as a model for the development of other new sensing systems.