Long-Term Storage and Reusability of Living Bacteria-Encapsulated Polyethylene Oxide Nanofiber Mats for Reactive Dye Removal

From food to environmental applications, the encapsulation of bio-objects in nanofibers is widely used. In particular, for improved and sustainable performance of bioremediation, the system requires the development of cost-effective nanomaterials that containing living microorganisms for textile wastewater treatment is required. Here, bacteria-encapsulated polyethylene oxide (PEO) nanofibers (Nfs) were prepared by electrospinning. According to the Scanning Electron Microscope (SEM) images, PEO-Nfs show bead-free morphology and homogeneous distribution, while random expansions are observed in the nanofibers after bacterial encapsulation. While the number of live bacteria in the polymer before electrospinning was 10 10 CFU/mL, the number of live bacteria-encapsulated after spinning was 10 8 CFU/mL. This proves that nanofibers carry a very high number of bacteria after electrospinning which is supported by Fluorescence microscope images. Furthermore, an ATR-FTIR study confirmed the molecular interactions between PEO and bacteria in the nanofibers. The removal efficiency of PEO_bacteria-Nfs was 26.6 ± 0.3% at 5 ppm and 9 ± 0.1% at 20 ppm dye concentration. Under storage conditions of +4 °C, the bacteria-encapsulated in PEO-Nfs show cell viability for more than 60 days. In order to extend the research on bacteria-encapsulated polymer Nfs, we explored the possibility of extending the life of bacteria in electrospun Nfs by cross-linking approaches using non-toxic calcium ions. The composite Nf mats were therefore reused for up to 4 repeated cycles.