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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.

The fungal strain Aspergillus ibericus was isolated from food waste for the production of pectinase. In this study response surface methodology (RSM) was employed to determine optimum conditions for the production of pectinase from citrus pectin. The optimum conditions for the production of pectinase were found to be pH, 4.0; temperature, 40 °C; incubation time, 120 h and substrate concentration (Citrus Pectin), 2% (w/v). The maximum activity of pectinase at optimum conditions was found to be 69.9 U mL−1. The purification by DEAE-Cellulose increased the specific activity of pectinase by about 10.1 fold from 64 to 650 U mg−1 protein. The molecular weight of the purified pectinase was found to be 41 kDa and 43 kDa. The purified pectinase was immobilized onto functionalized nanoporous activated carbon (FNAC), the maximum immobilization capacity of pectinase onto FNAC was found to be 3360 U g−1 at optimum immobilization conditions; time, 150 min; pH, 5.0; temperature, 35 °C and initial concentration of pectinase, 52 × 103 U (80 mg) L−1. The immobilized pectinase showed better thermal and storage stability than free pectinase. The immobilization of pectinase onto FNAC obeyed the Freundlich isotherm model. The immobilization of pectinase onto FNAC was confirmed by FT-IR, XRD, TGA, DSC and SEM analyses. The pectinase immobilized FNAC packed bed column reactor was used for the treatment of pectin containing wastewater under continuous mode. The maximum treatment efficiency for citrus pectin in synthetic wastewater was observed to be 82% at operating conditions: Hydraulic retention time, 180 min; pH, 5.0 and citrus pectin concentration 1% (w/v). Further, the citrus processing industrial wastewater was treated in pectinase immobilized FNAC packed bed column reactor and the system showed 94% of pectin treatment. The treatment of pectin in wastewater obeyed pseudo second order rate kinetic treatment model. The treatment of pectin in wastewater was confirmed by UV–vis spectroscopy and FT-IR spectrophotometer analyses.

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.

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.

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.

Anaerobic digestion of post-tanning wastewater was performed in batch anaerobic digester to evaluate the effect of COD/sulphate ratio [0.62, 0.69, and 1.20 (w/w) %] and F/M ratio [0.2, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, and 1.5 (w/w) %)] on the removal efficiency of COD. The F/M ratio of 0.3 was found to be the optimum ratio for the removal of COD by 53, 57, and 65%, respectively at COD/sulphate ratio of 0.62, 0.69, and 1.20. The maximum sulphate removal was observed at F/M ratio of 0.2 and the removal efficiency was 48, 50, and 58% at COD/sulphate ratio of 0.62, 0.69, and 1.20, respectively. The removal efficiency of COD and sulphate was increased with increase in COD/sulphate ratio from 0.62 to 1.20 and decreased with increase in F/M ratio from 0.2 to 1.5 in anaerobic digestion of post-tanning wastewater. The maximum concentration of sulphide formation was 784 mg/L at COD/sulphate ratio of 0.62 in anaerobic digestion process and the process was inhibited at this sulphide concentration. The microbial activity in the sludge was evaluated through live and dead cell assay using fluorescent microscopy. The maximum amount of dead microbes was observed in the anaerobic digester, which was operated at COD/sulphate ratio of 0.62 than other studied ratio.