Stable immobilization of bacterial endospores in reusable g-C3N4 pellets at room temperature

The present study explores the feasibility of a stable endospore immobilization in a porous substrate material at room temperature (⁓35 °C). In particular, the endospore of a Gram positive bacterium, isolated from an industrial wastewater, was successfully immobilized in a graphitic carbon nitride (g-C3N4) pellet. The endospores were found to be capable of self-transforming to active bacterial cells when brought in contact with the aqueous medium. The utility of such an endospore-carbonaceous composite material was recognized by assaying its activity towards the degradation of aqueous methylene blue (MB). The test data showed ∼99% removal of MB at the initial concentration of 10 mg L− 1 using the material dose of 6 g/L at 35 °C; the removal of the organic dye molecules in the endospores-immobilized pellet attributed to the adsorption by porous g-C3N4 and degradation by the bacterial cells that were transformed from endospores. The spent pellet was successfully reused following a simple washing procedure and re-immobilizing it with endospores, indicating the regenerability of the substrate material. The stability test showed that the endospore-immobilized g-C3N4 solid pellets, post storage at room temperature for 30 days, retained the bacterial activity without requiring any nutrient supplement. The endospore-immobilized g-C3N4 pellet synthesized in this study is likely to find multivariate applications, viz. photobio catalyst for wastewater treatment, vaccines and therapeutic agents, and microbe-carrier for plant growth. [Display omitted] •Bacterial endospores were successfully immobilized in g-C3N4 pellets.•Immobilized endospores were found to be stable at room temperature.•Approximately 99% of MB was removed from water using ES_g-C3N4.•Spent ES_g-C3N4 was efficiently reused following a simple washing procedure.