Abstract: A diagnostic device for measuring biochemical characteristics of microorganisms. A first chamber is provided into which is inoculated a test suspension containing an unknown organism. First passage means selectively provides liquid communication between the first chamber and a second chamber. The second chamber provides for contacting the liquid suspension with a substrate reagent which is located therein. Second passage means connects the second chamber to a third and selectively allows liquid communication therebetween. The third chamber may contain a suitable detection means for identifying the biochemical characteristics of the reacted test suspension when brought into contact therewith.

Abstract: A diagnostic test system for detecting .beta.-galactosidase producing micro-organisms is prepared by impregnating one zone of a bibulous material with an aqueous acetone solution of an o-nitrophenyl-.beta.-D-galactopyranoside substrate and evaporating to dryness; and impregnating a contiguous and separate zone of the bibulous material with a solution of a microbiologically inert buffer system which will maintain a pH of from about 6.5 to 8.5 and evaporating to dryness. Preferably, the bibulous material contains 1.5 mg of dry o-nitrophenyl-.beta.-D-galactopyranoside and 0.02 millimoles of a buffer which will maintain a pH of 7.4. Optionally, a waterproof barrier zone and an identifying dye zone may be present. In use, the impregnated bibulous material is inserted into a test tube of a saline suspension of unknown organism and incubated for 4 hours. The development of a yellow coloration indicates that .beta.-galactosidase is produced by the organism being tested.