A sustainable bioinspired nano-assembly of live marine bacteria for mineralization of phenothiazine dye

Abstract

Bioinspired materials mimic the remarkable biological properties of natural systems, which promote microbial adherence and enhance the binding of pollutants, thereby improving the efficiency of water remediation processes. In this study, we report the assembly of a bio–nano interface using graphene oxide (GO) and live marine facultative anaerobic bacteria, Bacillus subtilis NAG1. Herein, we systematically investigate the interaction of NAG1 with a broad range of GO concentrations, ranging from 20 to 150 µg mL⁻¹, using cell viability assays and further optimize the biocompatibility across a pH range of 4 to 14. Our findings indicate that GO, at 50 µg mL⁻¹, showed biocompatibility and supported cell proliferation. This optimized GO–NAG1 nano-assembly was employed to efficiently degrade phenothiazine dyes – Azure A (Az-A) and Azure B (Az-B). Additionally, GO enhanced the production of ligninolytic enzymes including laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase (MnP) leading to complete dye breakdown as confirmed by LC-MS analysis. Overall, our study provides strong evidence of the mineralization of phenothiazine dyes using a live anaerobic marine epiphytic bacterial system with GO.