New method of detection of certain bacterial oxidoreductases and transaminases by the Indicator reaction on agar

A method for detection of the following enzymes is described: glutamate oxalacetate transaminase (L-aspartate: 2-oxoglutarate aminotransferase, 2. 6. 1. 1), lactate dehydrogenase (L-lactate: NAD oxidoreductase, 1. 1. 1. 27) and malate dehydrogenase (L-malate: NAD oxido-reductase, 1. 1. 1. 37), diffused from bacterial suspensions into agar, by means of a “sandwich” agar detector layer containing the specific substrates. The principle of the reaction: reduced nicotinamide-dinucleotide ? nicotinamide-adenine-dinucleotide (NADH₂?NAD) was used, in which fluorescence of NADH₂ (in u. v. light) disappears proportionately to the activity of the test enzyme in its diffusion zone.