An assay is provided for determining the presence of contaminating microbial host cells in a culturing vessel containing a microbial host cell strain that utilizes more than one carbohydrate source as a substrate comprising: (a) culturing the microbial host cell strain in the vessel, wherein the strain comprises nucleic acid encoding a polypeptide of interest and is genetically marked so as not to utilize a carbohydrate source as a substrate; (b) plating an isolated sample of culture from step (a) onto culture media supplemented with a carbohydrate source not utilized by the host cell strain as a substrate; (c) incubating the plated cells at a temperature and for a time sufficient for any positive colony to grow to a detectable level; and (d) detecting whether any colonies are growing on the supplemented culture media.

An assay is provided for determining the presence of contaminating microbial host cells in a culturing vessel containing a microbial host cell strain that utilizes more than one carbohydrate source as a substrate comprising: (a) culturing the microbial host cell strain in the vessel, wherein the strain comprises nucleic acid encoding a polypeptide of interest and is genetically marked so as not to utilize a carbohydrate source as a substrate; (b) plating an isolated sample of culture from step (a) onto culture media supplemented with a carbohydrate source not utilized by the host cell strain as a substrate; (c) incubating the plated cells at a temperature and for a time sufficient for any positive colony to grow to a detectable level; and (d) detecting whether any colonies are growing on the supplemented culture media.

The present invention relates generally to differential carbon source metabolism in the genus Listeria, metabolic, biochemical, immunological and genetic procedures to measure said differential carbon source metabolism and the use of these products to detect, isolate and/or distinguish species of the genus Listeria as well as detect, isolate and/or distinguish strains of species of Listeria. The present invention also contemplates test kits and enrichment media to facilitate these procedures.

The present invention is directed to methods and media for the isolation and presumptive identification of various bacteria. In particular, the organisms commonly associated with urinary tract infections are distinguished based on their colonial morphology and color.

Testing of samples in a small, closed, and easy-to-fill device. Simultaneous filling of a large number of test wells using a novel gas-venting design, allowing for multiparameter testing and/or identification of bacteria.