The study of antagonistic interactions among pelagic bacteria: a promising way to coin environmental friendly antifouling compounds

Ten strains of marine bacteria (SCH0401-SCH0410) were isolated from Ayajin, the east coast of South Korea. In spectrophotometer based chemotaxis assay the ethyl acetate extract (300 mu g) of SCH0402 decreased the optical density (OD) of the motile target strains SCH0401, SCH0402, SCH0407 and SCH0408 by two to six times when compared to control. Tributyltin oxide (TBTO) decreased the OD of all target strains by only two times. The most active strain SCH0402 was identified as Shewanella oneidensis by using 16S rDNA gene sequence analysis. Similarly, the target motile strains SCH0401, SCH0402, SCH0407 and SCH0408 were identified as Alteromonas marina, Shewanella oneidensis, Roseobacter gallaeciensis and Bacillus atrophaeus, respectively. The growth inhibition zone produced by the test bacterial extracts against the target strains were three to eight times smaller when compared to that of TBTO. Even though, SCH0402 showed six times weaker antibacterial activity, the repellent activity was three times stronger than TBTO. Therefore, the higher negative chemotactic activity would be better to select eco-friendly antifouling compounds than the other antibacterial activities.