Medium for the cultivation of microorganisms

Claim 1

A fluid medium, useful for microbiological work and for identification of a microorganism and mixtures of different microorganisms on the basis of their aerobic and nonaerobic growth properties, which medium need not be liquified by heating prior to inoculation, which is inert with respect to the microorganisms, is non-biodegradable and sterilizable without loss of its properties, which comprises as a viscosity control agent a synthetic or natural macromolecular substance selected from the group consisting of water-soluble derivatives of cellulose and water-soluble vinyl polymers, and which (1) has the properties of a liquid and is innoculatable and stirable to permit microorganisms to be distributed uniformly therein by stirring prior to or after development of the microorganism; (2) has a viscosity so low and remains so liquid that non-motile microorganisms after innoculation onto the surface of said liquid medium, sediment to the bottom of the medium by gravity alone, said liquid property being independent of exposure to heat; (3) has, however, such viscosity with respect to gases that diffusion of atmospheric oxygen from the surface of the medium into the body thereof is virtually nil; (4) said liquid and viscosity properties being stable from the time of innoculum with the microorganism through the time of cultivation and identification of said microorganism; and (5) wherein said liquid and viscosity properties are such that (a) strict aerobic microorgainisms, even though motile do not multiply inside the medium, (b) strict anaerobic bacteria multiply only in the depth of the medium, and (c) aeroanaerobic bacteria, even though non-motile multiply at the surface and in the depth of the medium.