Lateral detachment forces of Bacillus niabensis and Alteromonas litorea against antifouling paint additive

Bacterial adhesion on various marine biotic or abiotic surfaces and subsequent biofilm formation paves the path of biofouling in marine environment. The aim of the present investigation was to determine the lateral detachment forces between coated antifouling paint additive and local isolated marine bacteria; Bacillus niabensis and Alteromonas litorea using atomic force microscopy (AFM). A paint additive was prepared by employing the active compounds, silver ion (Ag+) and surfactant hexadecyltrimethylammonium (HDTMA) embedded in the kaolinite clay structure. An incubated 100 µL bacterial suspension loaded onto the coated antifouling paint additive were scanned using AFM with the scan rate of 40 µm/s and scan size of 10 × 10 µm2.  Lateral detachment force was measured from a lower set point value of 0.3V to a maximum set point 10.0V. A weak interaction was observed between the model bacteria and paint additive (Or-Ag-Kao) coated surface with the mean lateral detachment force of 139.4 nN (B. niabensis) and 146.2 nN (A. litorea). Major contact surface area reduction observed on paint additive (Or-Ag-Kao) coated surfaces with 0.275 µm2 for B. niabensis and 0.391 µm2 for A. litorea indicated that paint additive coating successfully minimized bacterial attachment on the surface. The antifouling paint additive shows a reduction in lateral forces and minimized its surface contact, which could further prevent the microfouling formation on marine structures.