title: Modulation of Staphylococcus aureus spreading by water.
abstract: Staphylococcus aureus is known to spread rapidly and form giant colonies on the surface of soft agar and animal tissues by a process called colony spreading. So far, the mechanisms underlying spreading remain poorly understood. This study investigated the spreading phenomenon by culturing S. aureus and its mutant derivatives on Tryptic Soy Agarose (TSA) medium. We found that S. aureus extracts water from the medium and floats on water at 2.5 h after inoculation, which could be observed using phase contrast microscopy. The floating of the bacteria on water could be verified by confocal microscopy using an S. aureus strain that constitutively expresses green fluorescence protein. This study also found that as the density of bacterial colony increases, a quorum sensing response is triggered, resulting in the synthesis of the biosurfactants, phenolic-soluble modulins (PSMs), which weakens water surface tension, causing water to flood the medium surface to allow the bacteria to spread rapidly. This study reveals a mechanism that explains how an organism lacking a flagellar motor is capable of spreading rapidly on a medium surface, which is important to the understanding of how S. aureus spreads in human tissues to cause infections.
authors.affiliation: Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang-Gung University, Taoyuan, 333, Taiwan.|Department of Laboratory Medicine, Chang-Gung Memorial Hospital, No. 5, Fusing St., Guishan, Taoyuan, 333, Taiwan.|Research Center for Bacterial Pathogenesis, Chang-Gung University, Taoyuan, 333, Taiwan.
authors.forename: Mei-Hui
authors.initials: MH
authors.lastname: Lin
authors.affiliation: Research Center for Bacterial Pathogenesis, Chang-Gung University, Taoyuan, 333, Taiwan.|Department of Microbiology and Immunology, Chang-Gung University, Taoyuan, 333, Taiwan.
authors.forename: Wan-Ju
authors.initials: WJ
authors.lastname: Ke
authors.affiliation: Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang-Gung University, Taoyuan, 333, Taiwan.
authors.forename: Chao-Chin
authors.initials: CC
authors.lastname: Liu
authors.affiliation: Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang-Gung University, Taoyuan, 333, Taiwan.
authors.forename: Meng-Wei
authors.initials: MW
authors.lastname: Yang
mesh_terms: D003470:Culture Media / Q000737:chemistry; D018613:Microscopy, Confocal; D008858:Microscopy, Phase-Contrast; D009038:Motion; D053038:Quorum Sensing; D013211:Staphylococcus aureus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D013501:Surface-Active Agents / Q000378:metabolism; D014871:Water Microbiology
chemical_list: D003470:Culture Media; D013501:Surface-Active Agents