The role of lipopeptides in Bacteria-Protozoa interactions

SP-07 The role of lipopeptides in Bacteria-Protozoa interactions Chunxu Song, Mark Mazzola, Judith vande Mortel, Jos Raaijmakers Phytopathology department of Wageningen University, the Netherlands Soil-dwelling Pseudomonas fluorescens SS101 produces cyclic lipopeptides (CLPs) which are biosurfactants with broad-spectrum antibiotic activities. Strain SS101 exhibited resistance to grazing by Naegleria Americana in vitro and superior persistence in soil in the presence of this bacteria predator. In contrast, a mutant of strain SS101 deficient in CLP biosyntheisis shows no resistance. The results further showed that exposure of strain SS101 to this protozoan predator resulted in upregulation of CLP biosynthesis genes. These findings document a new natural function of CLPs and highlight that bacteria-protozoa interactions can result in activation of an antipredator response in prey populations. However, the identity of signals that trigger CLPs biosynthesis are largely unknown and also other genes involved in this interactions remain elusive. To this end, a microarray was developed to identify more genes involved in this bacteria-protozoa interactions and the signals that trigger or modulate CLPs biosynthesis. Collectively, these results will provide new insights in prey-defence strategies and signal perception in bacteria-protozoa interactions.