Oxoid, has developed a new class of selective agents known as Inhibigens™. When added to a culture medium, these unique molecules provide highly specific selectivity and allow improved recovery of target organisms, including those that may be damaged or stressed.

Inhibigen technology, which is currently subject to a patent application, involves the use of an inhibitor molecule linked to a specific substrate. In this bound state, the inhibitor is non-toxic. However, if taken up by a cell and cleaved from the substrate, the Inhibigen molecule will prevent the organism from replicating. Only organisms with the required uptake mechanism and specific enzyme to cleave the inhibitor-substrate complex will be affected. This allows very specific inhibition of competing, non-target organisms.

Unlike conventional selective agents, such as antibiotics, Inhibigens can be engineered to have no inhibitory effect on the target organism – even when the cells are stressed. This means that recovery of specific organisms is improved in two ways: by reducing the growth of competing flora and by minimising exposure to potentially inhibitory components.

Peter Stephens, research and development manager, Oxoid, comments, "Inhibigen technology offers a new dimension in selective microbiology. It is a much more specific way of inhibiting competing flora, giving stressed target organisms a much better chance of recovery. This is particularly important in the isolation of environmental and product contaminants."

Oxoid Salmonella Chromogenic Medium II (OSCM II) is the first culture medium to incorporate Inhibigen technology, combining it with familiar chromogenic technology to provide excellent isolation and identification of Salmonella species. The Inhibigen used in OSCM II specifically inhibits the growth of E. coli, a common competing organism in Salmonella investigations. Salmonella colonies (bright purple) are easily identified and differentiated from other organisms, such as Klebsiella and Enterobacter (blue).

By enhancing the presumptive identification of Salmonella colonies, OSCM II reduces the number of suspect cultures requiring confirmation.

Cheryl Mooney, food and industrial applications manager, Oxoid, comments, "The launch of OSCM II represents a significant milestone in the development of culture media, in keeping with our commitment to providing high quality products that offer real and measurable advantages to our customers."

For further information about Inhibigen technology and OSCM II, please contact Oxoid, using the contact details at the top of this page.