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, including structure, morphology, and functionality. Such surfaces can be modified to promote microbial adherence and enhance binding of pollutants, thereby improving the efficiency of water remediation processes. In the study, we have reported the assembly of a bio-nano interface using graphene oxide (GO) and live marine facultative anaerobic bacteria, Bacillus subtilis NAG1. GO possesses high surface area, surface functional groups such as hydroxyl, epoxy, and carboxyl groups, and hydrophilicity, which acts as a biomimetic scaffold to enhance bacterial adhesion and proliferation. Herein, we systemically investigated the interaction of NAG1 with a broad range of GO concentration, ranging from 20 to 150 μgmL-1, using cell viability assays and further optimized the biocompatibility across a pH range, from acidic to alkaline (4 to 14). The optimum GO-NAG1 nano-assembly was used for the degradation of phenothiazine dyes – Azure A (Az-A) and Azure B (Az-B), which are commonly used in textile applications. Our findings indicate that GO, at 50 μgmL-1, showed biocompatibility and enable cell proliferation. The optimized nano-assembly of live marine bacteria and GO was further employed for the degradation of Az-A and Az-B dyes, and the degradation pathway was elucidated by LC-MS analysis. Our study provides strong evidence of mineralization of phenothiazine dyes using live anaerobic marine epiphytic bacterial system with GO.