Patrik Pařík

Response of the bioluminescent bioreporter Pseudomonas fluorescens HK44 to analogs of naphthalene and salicylic acid.

Pseudomonas fluorescens HK44 is alux-based bioluminescent bioreporter capable of selective luminescence in the presence of naphthalene and/or salicylic acid intermediate of its metabolism. We attempted to induce bioluminescence (BL) in this strain with 72 compounds,viz. substituted naphthalenes, naphthalene-like compounds (e.g., quinoline), substituted salicylic acids, salicylic acid-like compounds (e.g., 2-anthranilic acid), oligocyclic aromates, and intermediates of naphthalene metabolism to better discriminate response specificity. From them, 42 induced BL significantly lower as compared to naphthalene, three (viz. isoquinoline,o-cresol, and salicylamide) induced BL significantly greater than naphthalene, and 27 yielded no bioluminescent response whatsoever. Strain HK44 is therefore not prone to extensive false-positive signaling and can serve as a fairly specific indicator organism for naphthalene bioavailability. At elevated concentrations, 41 compounds inhibited BL. Thus, the inclusion of constitutive bioreporter controls as indicators of sample toxicity is vital to successful biosensing application.

Automatic formation of hypotheses on the relationships between structure of naphthalene analogs and bioluminescence response of bioreporter Pseudomonas fluorescens HK44

Seven hypotheses on relationships between the structure of naphthalene analogs and bioluminescence response of bioreporter Pseudomonas fluorescens were formulated using GUHA (General Unary Hypotheses Automaton) on a training set of 37 compounds. Prediction of bioluminescence response of 12 new naphthalene analogs was successful in 69 % cases and resulted in rejection of single hypothesis. The results demonstrate applicability of GUHA in structure-activity research, especially for qualitative data.

4,5-Diiodo-2-phenyl-1H-imidazole

The structure of the title compound, C9H6I2N2, contains two symmetry-independent molecules. The interplanar angles between the imidazole and phenyl ring planes are 16.35 (3) and 17.48 (6)°. Molecules are connected via N—H⋯N hydrogen bonds to form zigzag chains along the b axis. The title compound is the first example of a structurally characterized 4,5-diiodoimidazole with an organic substituent in the 2-position and without protection on the N—H group of imidazole.