**4. Conclusions**

The newly isolated halotolerant *O. arctica* YHY1 used in the present study generates a higher and stable electric current for a longer time by using seafood processing waste chitin as a carbon source. Monomeric GlcNAc and metabolites like acetate, lactate, and propionate produced during chitin degradation were consumed by strain YHY1 in a timely manner. The performance of the bacterium was improved by supplementing the MFCs with a salt concentration of 40 g L−1. Further, *O. arctica* YHY1 can transfer electrons directly to the anode surface using membrane-bound cytochromes, with the partly involvement of extracellular redox mediators. Therefore, the findings of the present study can provide insights for utilizing chitin waste under high salt conditions, which can serve a dual purpose of recycling the seafood chitin biomass and generating electricity.

**Author Contributions:** Conceptualization, R.G.; Methodology, R.G.; Software, T.-R.C.; Validation, H.-J.K. and H.-J.L.; Formal analysis, J.-Y.C.; Investigation, R.G.; Resources, S.H.; Data curation, M.-J.S.; Writing—original draft preparation, R.G.; Writing—review and editing, S.K.B., S.-K.K. and D.-W.Y.; Visualization, S.-H.K.; Supervision, Y.-H.Y.; Project administration, Y.-H.Y.; Funding acquisition, Y.-H.Y. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by the National Research Foundation of Korea (NRF) (NRF-2019R1F1A1058805 and NRF-2019M3E6A1103979) and the Research Program to Solve the Social

Issues of the NRF funded by the Ministry of Science and ICT (2017M3A9E4077234). This work was also supported by the R&D Program of MOTIE/KEIT (20016324).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.

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