Advances in culture media design (Chromogen and Inhibigen compounds) Neal Parker Industrial account manager

2 Introduction Background and principles of Chromogens Why do we use them? Background and principles of Inhibigens Why do we use them?

3 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”

4 E. coli Chromophore component (e.g. indoxyl derivative such as 5-bromo-4-chloro-3-indoxyl) Sugar component (e.g. galactose) Uptake Enzyme Chromogen Background and principles of chromogenic media

5 E. coli

6 Background and principles of chromogenic media

7 Why use Chromogens?

8 Improve overall specificity of a diagnostic medium. Positive colonies are easy to identify. Reduce number of sub-cultures required.

9 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

10 From chromogens to inhibigens…

11 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 ”

12 Uptake Inhibition of cell wall synthesis Loss of viability Inhibitor component (AEP) Sugar or amino acid component Inhibigen TM Specific enzyme hydrolysis - X Free inhibitor in medium is not actively taken up Background and principles of Inhibigens

13 XLDBrilliance Salmonella (Inhibigen TM ) Why use Inhibigens?

14 Why use Inhibigens? Reduce stress on target organism Improve sensitivity Reduce growth of non-target organisms

15 Current Inhibigen Situation Inhibigens are a patented concept Small scale manufacture Currently only one product containing Inhibigen compounds Many more are in the pipeline