Abstract: Apparatus for growing cultures of microorganisms comprised of an inert ri porous member having passageways extending therethrough and structure for bringing liquid in contact with one side of the member. In one species of the invention, the passageways are small enough to prevent microorganisms from flowing through them.

Abstract: A method and device for detecting bacteria by forming an immunoassay ladder sing a biological substance (Ag) adsorbed onto a surface, to which has been added an immunological biochemical ladder (Ab) and beta-galactosidase enzyme (gal) to form a Ag-Ab-gal system. The system is added to an aqueous solution of an enzyme selected from ortho-nitrophenylgalactopyranoside and ortho-nitrophenylgalactosidase enzyme. The enzyme reacts with the gal to produce ortho-nitrophenol (ONP) such that the amount of ortho-nitrophenol (ONP) produced may be detected by measuring the vapor pressure generated by the ONP using an ion mobility spectrometer monitor. The pressure of the ONP is in proportion to the amount of biological substance present in the system. In a preferred embodiment, the ion mobility spectrometer monitor includes display means for indicating the quantity of bacteria measured.