**4. Conclusions**

In our previous study, we found that a silver nanoparticle-dispersed silane-based coating effectively inhibited biofilm formation. Here, we attempted the analysis of microbiomes on biofilms formed on the coatings using an NGS technique. No archaea phyla were detected on the biofilms of Ag, whereas only one archaea phylum was detected on the biofilms of Non-Ag. Proteobacteria were the dominant bacterial phylum on the biofilms of both Non-Ag and Ag. Comparing OTUs of the biofilms on Ag with those of the biofilms on Non-Ag, no distinct difference was noted in bacterial orders, but biofilm-forming bacterial orders and a biocorrosion-protective bacterial order were found to be present in both biofilms. In addition, members of *Marinomonas* were the main biofilm-forming bacteria under aerobic conditions, but were replaced by those of *Anaerospora* under anaerobic conditions. Moreover, the addition of silver nanoparticles did not affect the microbiome of biofilms on silane-based coating, while it decreased the amount of biofilm on it.

**Author Contributions:** Conceptualization, A.O.; Methodology, A.O., K.T. and H.K.; Validation, A.O.; Investigation, A.O.; Resources, K.T., H.K, K.S., T.Y. and T.S.; Data Curation, A.O.; Writing-Original Draft Preparation, A.O.; Writing-Review & Editing, A.O. and S.T.; Visualization, A.O. and K.T.; Supervision, A.O.; Project Administration, A.O.; Funding Acquisition, A.O. and H.K.

**Funding:** This research was partly funded by Suga weathering technology foundation in 2016.

**Conflicts of Interest:** The authors declare no conflict of interest.
