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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.

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.

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.