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Cheap and efficient bioactive materials capable of producing potable water are in high demand. We synthesized bioactive prodigiosin-conjugated iron-oxide-activated carbon composite ([Ac]F@Fe3O4–PG) for the effective removal of microbial contaminants without biofilm formation. The disinfection effect of [Ac]F@Fe3O4–PG was investigated against antibiotic-resistant Escherichia coli and Bacillus cereus. The reactive oxygen species, glutathione concentration, and intracellular leakages assay, zeta potential, atomic force microscopy, scanning electron microscopy, and fluorescence microscopy were performed to understand the mechanistic route of bacterial disinfection. Results demonstrate the bacterial cell membrane damage due to the surface charge neutralization by cationic [Ac]F@Fe3O4–PG, thereby affecting the transport system of the cells. The generation of reactive oxygen species further triggered programmed bacterial cell death with apoptosis-like changes in cellular morphology. We demonstrate that the [Ac]F...

The objective of this investigation was to explore the antioxidant and antimicrobial property of bioactive prodigiosin produced from Serratia marcescens using rice bran. The antioxidant potential of prodigiosin was examined by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging method via UV–visible, electron spin resonance spectrum (ESR), cyclic voltammetry and excitation emission spectrum. The antimicrobial activity of prodigiosin was examined against foodborne pathogens. The shelf life extending capacity of prodigiosin was evaluated with meat extract powder (MEP) as a model food material. The DPPH and ABTS radicals were completely scavenged by prodigiosin at the concentration of 10 mg/L. The food spoilage was inhibited by the addition of prodigiosin with MEP and it was compared with conventional preservative. The prodigiosin has prohibited the growth of foodborne pathogens effectively and the shelf life of the food was also extended significantly. The antimicrobial edible preservative developed in this study inhibited the growth of the microbial populations that produced through storage of the MEP and free radical scavenging activity. The results reveal that the bioactive prodigiosin effectively scavenged the free radical and inhibited the bacterial growth in food stuff.

A novel method for the extraction of prodigiosin from bacterial fermentation was achieved using an integrated sequential batch extraction reactor (SBER) containing functionalized iron oxides ([Fe 3 O 4 ] F ). The [Fe 3 O 4 ] F was prepared using diethanolamine to impart quaternary amine group onto Fe 3 O 4 . The quaternary amine group imparted to Fe 3 O 4 enhanced the prodigiosin adsorption efficiency. Two SBER were integrated with the continuous fermenter for the continuous extraction of prodigiosin. The present investigation established a method to conserve solvent by about 95% during the prodigiosin extraction step. The proposed extraction method can be regarded as solvent free direct extraction of bacterial bioactive compounds from bacterial fermented medium.

Prodigiosin (PG) is a bioactive compound produced by several bacterial species. Currently, many technologies are being developed for the production of PG by fermentation processes. However, new challenges are being faced with regard to the production of PG in terms of the recovery and purification steps, owing to the labile nature of PG molecules and the cost of the purification steps. Conventional methods have limitations due to high cost, low reusability, and health hazards. Hence, the present investigation was focused on the development of surface-functionalized magnetic iron oxide ([Fe3O4]F) for solvent-free extraction of bioactive PG from the bacterial fermented medium. Fe3O4 was functionalized with diethanolamine and characterized by FT-IR, diffuse reflectance spectroscopy, thermogravimetric analysis, scanning electron microscopy, and confocal microscopy. The various process parameters, such as contact time, temperature, pH, and mass of Fe3O4, were optimized for the extraction of PG using functionalized Fe3O4. Instrumental analyses confirmed that the PG molecules were cross-linked with functional groups on [Fe3O4]F through van der Waals forces of attraction. PG extracted through Fe3O4 or [Fe3O4]F was separated from the fermentation medium by applying an external electromagnetic field and regenerated for successive reuse cycles. The purity of the extracted PG was characterized by high-performance liquid chromatography, FT-IR, and UV-visible spectroscopy. The iron oxide-diethanolamine-PG cross-linked ([Fe3O4]F-PG) composite matrix effectively deactivates harmful fouling by cyanobacterial growth in water-treatment plants. The present investigation provides the possibility of solvent-free extraction of bacterial bioactive PG from a fermented medium using functionalized magnetic iron oxide.

Microcystin is heterocyclic toxin released from dead cyanobacterial cells, and their potential occurrence in drinking water sources prompted investigations into remedial water treatments for their removal. The present investigation employed the magnetic iron oxide extracellular polymer (ECP–Fe3O4) composite for the effective removal of microcystin from treated wastewater. The extracellular polymer produced from bacterial cell was impregnated with magnetite to develop ECP–Fe3O4 composite. The ECP–Fe3O4 matrix was characterized by optical microscope, FTIR, XRD. The ECP–Fe3O4 matrix was used for the removal of microcystin in aqueous solution. ECP–Fe2O3 matrix removed microcystin about 96% after treated water. ECP–Fe3O4 effectively removed the microcystin as the ECP and Fe ion-integrated matrix is an effective complex with special functional groups such as carboxylic and amide groups to sequester microcystin in aqueous solution. The matrix was separated by the application of magnetic field. The separated matrix was reused for the microcystin removal, and the efficiency of recovered ECP–Fe3O4 was consistent even after several cycles for the removal of microcystin. The microcystin removal was confirmed by UV–visible spectral analysis.

The increase in concern over safe water for human consumption demands disinfection of water. Conventional chemical disinfection methods release counter ions into the treated water and they impair human health significantly. The present investigation was focused on the disinfection of pathogenic bacteria via a bio-disinfection route using a prodigiosin-impregnated cellulose column reactor (PICCR). Escherichia coli and Bacillus cereus were chosen as model pathogens to validate the efficiency of the PICCR for pathogen removal from water. The pathogen removal efficiency was evaluated by the pour plate method, regrowth ability in nutrient broth and quantitative estimation of live and dead cells using fluorescent microscopy. The PICCR showed effective reduction of E. coli by 97.31% and B. cereus by 97.33%. Further, bacterial cell membrane damage by bio-disinfection was verified through analysis of the residual protein and nucleic acid in the treated water using UV-visible spectroscopy, a trans-illuminometer and SDS PAGE. The proposed PICCR was found to be effective for the removal of pathogens from water and this may be regarded as a viable purification technique for drinking water.