Figure 1. Quenching of QS-regulated pigments and bioluminescence by S. delphini.

P. aeruginosa (A), S. marcescens (B), V. harveyi (C) and C. subtsugae (D) were each co-cultivated with S. aureus (1) or S. delphini (2) for 24 h. Pyocyanin, which is excreted by P. aeruginosa, was determined in the supernatant at its absorption maximum A_{520 nm}. Prodigiosin, which is cell wall bound in S. marcescens, was ethanol-extracted from the cell pellet and determined at its absorption maximum A_{534 nm}. Bioluminescence of V. harveyi was intensified by aeration before measuring in a bioluminescence reader. Violacein from C. subtsugae was quantitatively extracted with butanol and determined at its absorption maximum A_{585 nm}.