Biofilm formation in marine bacteria and biocidal sensitivity: interplay between a potent antibiofilm compound (AS162) and quorum-sensing autoinducers.

The capacity of two homoserine lactones to stimulate the marine bacteria (TC14 strain) for its capacity to form a biofilm when exposed to a potent antibiofilm compound AS162 is reported. Effective concentrations (EC) of AS162 at 24 h, 48 h, and 72 h were, respectively, of 4.3, 4.4, and 6.0 µM. When tested in combination with HSLs, results showed that quorum-sensing signal molecules 3-oxo-C6 and 3-oxo-C8 homoserine lactones do not act directly on the biofilm formation, but are able to interfere positively with AS162 to promote biofilm growth with EC ranging from 30 to 50 µM. The same results were obtained with two other marine bacterial strains: TC8 and sp. 4M6. These findings suggest that HSLs can significantly affect the biocidal sensitivity of marine bacteria to antifouling agents.