Increase in rhamnolipid synthesis under iron-limiting conditions influences surface motility and biofilm formation in Pseudomonas aeruginosa.
Iron is an essential element for life but also serves as an environmental signal for biofilm development in the opportunistic human pathogen Pseudomonas aeruginosa. Under iron-limiting conditions, P. aeruginosa displays enhanced twitching motility and forms flat unstructured biofilms. In this study, we present evidence suggesting that iron-regulated production of the biosurfactant rhamnolipid is important to facilitate the formation of flat unstructured biofilms. We show that under iron limitation the timing of rhamnolipid expression is shifted to the initial stages of biofilm formation (versus later in biofilm development under iron-replete conditions) and results in increased bacterial surface motility. In support of this observation, an rhlAB mutant defective in biosurfactant production showed less surface motility under iron-restricted conditions and developed structured biofilms similar to those developed by the wild type under iron-replete conditions. These results highlight the importance of biosurfactant production in determining the mature structure of P. aeruginosa biofilms under iron-limiting conditions.
The Bacterial Biofilm Research Laboratory, The Institute for Nanotechnology and Advanced Materials, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel.
Rivka
R
Glick
Christie
C
Gilmour
Julien
J
Tremblay
Shirley
S
Satanower
Ofir
O
Avidan
Eric
E
Déziel
E Peter
EP
Greenberg
Keith
K
Poole
Ehud
E
Banin
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006017:Glycolipids / Q000096:biosynthesis*; D006801:Humans; D007501:Iron / Q000378:metabolism*; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000502:physiology*
D001426:Bacterial Proteins; D006017:Glycolipids; C418382:rhamnolipid; D007501:Iron