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Advances in culture media design (Chromogen and Inhibigen compounds). Neal Parker Industrial account manager. Introduction. Background and principles of Chromogens Why do we use them? Background and principles of Inhibigens Why do we use them?.
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Advances in culture media design (Chromogen and Inhibigen compounds) Neal Parker Industrial account manager
Introduction • Background and principles of Chromogens • Why do we use them? • Background and principles ofInhibigens • Why do we use them?
Background and principles of chromogenic media • Chromogen – “a chemical compound, itself without colour, that can be transformed into a coloured compound, or can react with another material to form a coloured compound”
Background and principles of chromogenic media Chromogen Sugar component (e.g. galactose) Chromophore component (e.g. indoxyl derivative such as 5-bromo-4-chloro-3-indoxyl) Uptake E. coli Enzyme
Why use Chromogens? • Improve overall specificity of a diagnostic medium. • Positive colonies are easy to identify. • Reduce number of sub-cultures required.
Current chromogen situation • The large scale synthesis of chromogens means compounds are affordable for use in culture media • There are now chromogenic media available for almost all organisms of interest in both the Industrial and Clinical environments • >30 chromogenic media formulations are currently available for the differentiation of E. coli and coliforms • >10 formulations for Salmonella
Background and principles of Inhibigens • Inhibigen – “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”
Background and principles of Inhibigens - InhibigenTM Free inhibitor in medium is not actively taken up X Sugar or amino acid component Inhibitor component (AEP) Specific enzyme hydrolysis Uptake Inhibition of cell wall synthesis Loss of viability
Why use Inhibigens? • XLD • Brilliance Salmonella (InhibigenTM)
Why use Inhibigens? • Reduce stress on target organism • Improve sensitivity • Reduce growth of non-target organisms
Current Inhibigen Situation • Inhibigens are a patented concept • Small scale manufacture • Currently only one product containing Inhibigen compounds • Many more are in the pipeline