An iron detection system determines bacterial swarming initiation and biofilm formation

Chuan Sheng Lin, Yu Huan Tsai, Chih Jung Chang, Shun Fu Tseng, Tsung Ru Wu, Chia Chen Lu, Ting Shu Wu, Jang Jih Lu, Jim Tong Horng, Jan Martel, David M. Ojcius, Hsin Chih Lai, John D. Young*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Iron availability affects swarming and biofilm formation in various bacterial species. However, how bacteria sense iron and coordinate swarming and biofilm formation remains unclear. Using Serratia marcescens as a model organism, we identify here a stage-specific iron-regulatory machinery comprising a two-component system (TCS) and the TCS-regulated iron chelator 2-isocyano-6,7-dihydroxycoumarin (ICDH-Coumarin) that directly senses and modulates environmental ferric iron (Fe 3+) availability to determine swarming initiation and biofilm formation. We demonstrate that the two-component system RssA-RssB (RssAB) directly senses environmental ferric iron (Fe 3+) and transcriptionally modulates biosynthesis of flagella and the iron chelator ICDH-Coumarin whose production requires the pvc cluster. Addition of Fe 3+, or loss of ICDH-Coumarin due to pvc deletion results in prolonged RssAB signaling activation, leading to delayed swarming initiation and increased biofilm formation. We further show that ICDH-Coumarin is able to chelate Fe 3+ to switch off RssAB signaling, triggering swarming initiation and biofilm reduction. Our findings reveal a novel cellular system that senses iron levels to regulate bacterial surface lifestyle.

Original languageEnglish
Article number36747
JournalScientific reports
StatePublished - 15 Nov 2016


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