Rcr Scientific, Inc.

Gordon L Bontrager

Jonathan N Roth

A test method and medium for quantitatively identifying and distinguishing biological materials in a test sample. A first biological material has enzyme specificity for a first chromogenic substrate, a second biological material has enzyme specificity for a second chromogenic substrate, and a third biological material has specificity for one of the substrates. The chromogenic substrates form respective first and second colored water insoluble compounds upon reaction with specific enzymes. The first and second biological materials are capable of fermenting a sugar, and the third material does not ferment sugar. The test medium is adjusted to a pH conducive for color change of a pH indicator upon acidification due to fermentation, resulting in the formation of a zone of a third color around the water insoluble compounds of the sugar-fermenting materials. The sample is incubated, and examined for the presence of colonies of the first biological material, having the first color and an encircling zone of the third color; for colonies of the second material, having the second color and the encircling colored zone; for colonies of a third material having the first color, and not having the colored zone; and for colonies having neither color, with or without the colored zone, representing colonies of other biological materials.

Test media and quantitative method for identification and

A plurality of petri dishes or other glass or plastic containers are coated on the inside bottom surface of the containers by passing the containers through a coating or layering apparatus. The apparatus includes an indexing conveyor to sequentially pass the open containers through a filling station where an amount of a coating material is applied while tilting the container to one side thereby distributing the material to the entire bottom surface of the container. The containers are conveyed to an aspirating station to aspirate excess material while tilting the container toward the aspirating nozzle. Subsequent to the aspiration step, the containers are tilted in the opposite direction to distribute the material in the container. The material is then dried and the containers stacked and packaged. The coating material includes metal ions such as calcium or other divalent metal ions, in a suitable carrier that is able to bond the bottom inside surface of the container. The coating material forms a dehydrated, solidified layer bonded onto the bottom surface of the container. The coating material can be a water/agar solution or a plastic resin in an appropriate solvent containing the calcium ions.

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South Bend, IN, United States of America

Gordon L Bontrager