Biosensor for lactate determination in biological fluids. I. Construction and properties of the biosensor.

The preparation of a biosensor for lactate determination is described. The biosensor is based on an immobilized suspension of the aerobic yeast Hansenula anomala, containing flavocytochrome b2 in high activity. The conditions for yeast cultivation were optimized to gain a sufficiently high activity of this enzyme converting lactate in the cells. The properties of the biosensor are compared with those of a sensor based on immobilized enzyme flavocytochrome b2. The yeast lactate biosensor has a sufficient sensitivity and linearity and short time of response. The precision and accuracy of lactate determination as well as the results of comparisons using an enzyme electrode and the spectrophotometric UV-test, enables this biosensor to be used in routine work. Analysis can be performed in blood plasma or whole blood. The stability of the biosensor makes it possible to work for 4 weeks with one yeast cell pellet.