Kevin R. Oldenburg

A Dual Culture Assay for Detection of Antimicrobial Activity

Combinatorial chemistry has opened a new realm of chemical diversity in the search for useful therapeutics as well as the ability to generate chemical libraries of hundreds of thousands to millions of discrete compounds. For the biologist, the goal is to screen these large libraries quickly and to obtain as much information in the primary screen as possible. Ideally, a primary screen would not only identify potential lead compounds but also yield information about the specificity, toxicity, and potency of that compound. Toward this end, a primary screen has been developed in which two organisms are cocultured, either bacteria, yeast, or mammalian cells, in the presence of a combinatorial library. For example, bacteria and yeast are cocultured either in liquid or in agar. When exposed to compounds from the combinatorial library, individual compounds are found which inhibit bacterial growth antibacterialls, inhibit yeast growth (antifungals), or inhibit both (potential toxins). This screening method is simple, rapid, and eliminates many of the false positives usually encountered in antimicrobial screening.

Development of an ultrahigh-throughput screening system: plate design, liquid handling, and image analysis

Recent advances in plate design, liquid handling, and imaging have made it possible, for the first time, to create truly ultra-high throughput screening systems. The key engineering challenges which needed to be overcome in order to develop this system as well as system limitations are discussed. Data from model systems is presented comparing the results obtained from the miniaturized format with those obtained from the standard 96-well format. These results demonstrate that the signal to noise ratio and robustness of an assay can be preserved upon ultra-miniaturization. The flexibility of this system should make it amenable for screening of not only pharmaceuticals but also for agrochemicals and applied materials.