Studies on the sensor for the determination of total viable counts.

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Objectives 1) Preparation of the sensor for the determination of total viable bacterial cell counts. 2) Establishment of the optimum conditions for Using the proposed sensor. 3) Application of the proposed sensor to the determination of total viable cell counts in fish meat.Methods Each one ml of bacteria suspensions was filtered through a membrane filter. The filter was fixed at the tip of an oxygen electrode and covered with a dialysis membrane. The output currents of the sensor for phosphate buffer and culture medium saturated with oxygen were determined, respectively. The total viable counts against the difference between both current decreases were plotted on the semi-logarithmic graph.Results 1) Sensors for the determination of total viable counts were prepared from A. putrefaciens, E. coli, L. casei, Staphylococcus, P. fluorescens, and the mixed bacteria except for L. casei, respectively, and oxygen electrode.2) The optimum conditions for each sensor were established as follows; A. putrefaciens: pH 7.2, 25ﾟC; E.coli: pH 7.2, 25ﾟC: L. casei: pH 6.8, 30ﾟC, Staphylococcus: pH 7.2, 25ﾟC; P. fluorescens: pH 7.2, 25ﾟC; mixed bacteria (except L. casei): pH 7.2, 25ﾟC. 3) Good relationships were obtained between total viable counts of pure bacteria and the current decreases of the sensors at the range of about 10^6 to 10^8/ml. 4) Good relationship was obtained between total viable counts in terms of A. putrefaciens and the output current of the sensor prepared from the mixed bacteria. 5) The total viable counts/g of bluefin tuna and mackerel meats at 5ﾟC for 3 days were determined in terms of A. putrefaciens. The influence of A. putrefaciens and P. fliuorescens on the output current of the sensor is under investigation now when they are superior in number to the other bacteria.