Norspermidine Is Not a Self-Produced Trigger for Biofilm Disassembly

• Published in: Cell Vol. 156; no. 4; pp. 844 - 854
• Main Authors: Hobley, Laura, Kim, Sok Ho, Maezato, Yukari, Wyllie, Susan, Fairlamb, Alan H., Stanley-Wall, Nicola R., Michael, Anthony J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 13.02.2014; Cell Press
• Subjects: Amino Acid Sequence; Bacillus subtilis; Bacillus subtilis - growth & development; Bacillus subtilis - physiology; Biofilms - growth & development; gamma-Aminobutyric Acid - metabolism; Matters Arising; Molecular Sequence Data; Plankton - growth & development; Sequence Alignment; Spermidine - analogs & derivatives; Spermidine - biosynthesis; Spermidine - metabolism; Spermidine - physiology; Vibrio cholerae; Vibrio cholerae - physiology
• ISSN: 0092-8674; 1097-4172; 1097-4172
• DOI: 10.1016/j.cell.2014.01.012

Formation of Bacillus subtilis biofilms, consisting of cells encapsulated within an extracellular matrix of exopolysaccharide and protein, requires the polyamine spermidine. A recent study reported that (1) related polyamine norspermidine is synthesized by B. subtilis using the equivalent of the Vibrio cholerae biosynthetic pathway, (2) exogenous norspermidine at 25 μM prevents B. subtilis biofilm formation, (3) endogenous norspermidine is present in biofilms at 50–80 μM, and (4) norspermidine prevents biofilm formation by condensing biofilm exopolysaccharide. In contrast, we find that, at concentrations up to 200 μM, exogenous norspermidine promotes biofilm formation. We find that norspermidine is absent in wild-type B. subtilis biofilms at all stages, and higher concentrations of exogenous norspermidine eventually inhibit planktonic growth and biofilm formation in an exopolysaccharide-independent manner. Moreover, orthologs of the V. cholerae norspermidine biosynthetic pathway are absent from B. subtilis, confirming that norspermidine is not physiologically relevant to biofilm function in this species. [Display omitted] •Norspermidine is not found or synthesized in Bacillus subtilis biofilms•Exogenous norspermidine inhibits growth of wild-type cells•Exogenous norspermidine inhibits growth of exopolysaccharide-deficient cells•Lower levels of exogenous norspermidine promote biofilm formation It has been reported that norspermidine is synthesized by the bacterium Bacillus subtilis and inhibits biofilm formation by condensing exopolysaccharide. Now it is shown that norspermidine is not synthesized by B. subtilis, and high levels of exogenous norspermidine inhibit cell growth in an exopolysaccharide-independent manner.