Inhibition of biofilm formation and swarming of Bacillus subtilis by (5Z)‐4‐bromo‐5‐(bromomethylene)‐3‐butyl‐2(5H)‐furanone

Aims: (5Z)‐4‐Bromo‐5‐(bromomethylene)‐3‐butyl‐2(5H)‐furanone(furanone) of the marine alga Delisea pulchra was synthesized, and its inhibition of swarming motility and biofilm formation of Bacillus subtilis was investigated. Methods and Results: Furanone was found to inhibit both the growth of B. subtilis and its swarming motility in a concentration‐dependent way. In addition, as shown by confocal scanning laser microscopy, furanone inhibited the biofilm formation of B. subtilis. At 40 μg ml−1, furanone decreased the biofilm thickness by 25%, decreased the number of water channels, and reduced the percentage of live cells by 63%. Conclusions, Significance and Impact of the Study: Natural furanone has potential for controlling the multicellular behaviour of Gram‐positive bacteria.