Marine Biofilm Model Comprising a Loop-Type Biofilm Reactor and a Halomonas Strain HIG FST4 1, an Active Biofilm-Forming Bacterium

In ocean and coastal waters, the formation of biofilms on artificial matters often causes intractable phenomena such as the deterioration of surface functions and corrosion, resulting in significant economic damage. Thus, methods for inhibiting biofilm formation are in high demand, and many new anti-biofilm products are being designed on a daily basis. However, practical and safe assays for evaluating anti-biofilm formation have not yet been established. In this study, we developed a more practical and safer biofilm formation test system composed of a loop-type laboratory biofilm reactor (LBR) and HIG FST4 1, a Halomonas strain derived from ballast seawater, in comparison with a slowly rotating test-tube culture (TTC) test. To evaluate biofilm formation in an LBR and TTC, three materials (pure iron, pure aluminum, and soda lime glass) were tested, and Raman spectroscopic analysis was used for the identification and relative quantification of the biofilm contents. Regardless of the test method, biofilm formation progressed in the order of soda lime glass < pure aluminum < pure iron. The Raman peaks showed that the LBR test samples tended to remove polysaccharides compared to the TTC test samples and that the proportion of proteins and lipids in the LBR test samples was much higher than that of the TTC test samples. These results show that the combination of HIG FST4 1 and LBR is suitable for biofilm formation in a practical marine environment.